Add faster test harness which fakes curses

babi.py

@@ -23,6 +23,7 @@ from typing import Match
 from typing import NamedTuple
 from typing import Optional
 from typing import Pattern
+from typing import Sequence
 from typing import Tuple
 from typing import TYPE_CHECKING
 from typing import TypeVar
@@ -1582,8 +1583,8 @@ def _color_test(stdscr: 'curses._CursesWindow') -> None:
     header += '<< color test >>'.center(curses.COLS)[len(header):]
     stdscr.insstr(0, 0, header, curses.A_REVERSE)
 
-    maxy, maxx = stdscr.getmaxyx()
+    # will be deleted eventually
-    if maxy < 19 or maxx < 68:  # pragma: no cover (will be deleted)
+    if curses.LINES < 19 or curses.COLS < 68:  # pragma: no cover
         raise SystemExit('--color-test needs a window of at least 68 x 19')
 
     y = 1
@@ -1735,11 +1736,11 @@ def make_stdscr() -> Generator['curses._CursesWindow', None, None]:
         curses.endwin()
 
 
-def main() -> int:
+def main(argv: Optional[Sequence[str]] = None) -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument('--color-test', action='store_true')
     parser.add_argument('filenames', metavar='filename', nargs='*')
-    args = parser.parse_args()
+    args = parser.parse_args(argv)
     with make_stdscr() as stdscr:
         c_main(stdscr, args)
     return 0

testing/runner.py

@@ -1,63 +1,54 @@
 import contextlib
-import shlex
-import sys
-from typing import List
 
 from hecate import Runner
 
-import babi
-
 
 class PrintsErrorRunner(Runner):
     def __init__(self, *args, **kwargs):
-        self._screenshots: List[str] = []
+        self._prev_screenshot = None
         super().__init__(*args, **kwargs)
 
     def screenshot(self, *args, **kwargs):
         ret = super().screenshot(*args, **kwargs)
-        if not self._screenshots or self._screenshots[-1] != ret:
+        if ret != self._prev_screenshot:
-            self._screenshots.append(ret)
-        return ret
-
-    @contextlib.contextmanager
-    def _onerror(self):
-        try:
-            yield
-        except Exception:  # pragma: no cover
-            # take a screenshot of the final state
-            self.screenshot()
             print('=' * 79, flush=True)
-            for screenshot in self._screenshots:
+            print(ret, end='', flush=True)
-                print(screenshot, end='', flush=True)
+            print('=' * 79, flush=True)
-                print('=' * 79, flush=True)
+            self._prev_screenshot = ret
-            raise
+        return ret
-
-    def await_exit(self, *args, **kwargs):
-        with self._onerror():
-            return super().await_exit(*args, **kwargs)
 
     def await_text(self, text, timeout=None):
         """copied from the base implementation but doesn't munge newlines"""
-        with self._onerror():
+        for _ in self.poll_until_timeout(timeout):
-            for _ in self.poll_until_timeout(timeout):
+            screen = self.screenshot()
-                screen = self.screenshot()
+            if text in screen:  # pragma: no branch
-                if text in screen:  # pragma: no branch
+                return
-                    return
+        raise AssertionError(
-            raise AssertionError(
+            f'Timeout while waiting for text {text!r} to appear',
-                f'Timeout while waiting for text {text!r} to appear',
+        )
-            )
 
     def await_text_missing(self, s):
         """largely based on await_text"""
-        with self._onerror():
+        for _ in self.poll_until_timeout():
-            for _ in self.poll_until_timeout():
+            screen = self.screenshot()
-                screen = self.screenshot()
+            munged = screen.replace('\n', '')
-                munged = screen.replace('\n', '')
+            if s not in munged:  # pragma: no branch
-                if s not in munged:  # pragma: no branch
+                return
-                    return
+        raise AssertionError(
-            raise AssertionError(
+            f'Timeout while waiting for text {s!r} to disappear',
-                f'Timeout while waiting for text {s!r} to disappear',
+        )
-            )
+
+    def assert_cursor_line_equals(self, s):
+        cursor_line = self._get_cursor_line()
+        assert cursor_line == s, (cursor_line, s)
+
+    def assert_screen_line_equals(self, n, s):
+        screen_line = self._get_screen_line(n)
+        assert screen_line == s, (screen_line, s)
+
+    def assert_full_contents(self, s):
+        contents = self.screenshot()
+        assert contents == s
 
     def get_pane_size(self):
         cmd = ('display', '-t0', '-p', '#{pane_width}\t#{pane_height}')
@@ -70,23 +61,22 @@ class PrintsErrorRunner(Runner):
         return int(x), int(y)
 
     def await_cursor_position(self, *, x, y):
-        with self._onerror():
+        for _ in self.poll_until_timeout():
-            for _ in self.poll_until_timeout():
+            pos = self._get_cursor_position()
-                pos = self._get_cursor_position()
+            if pos == (x, y):  # pragma: no branch
-                if pos == (x, y):  # pragma: no branch
+                return
-                    return
 
-            raise AssertionError(
+        raise AssertionError(
-                f'Timeout while waiting for cursor to reach {(x, y)}\n'
+            f'Timeout while waiting for cursor to reach {(x, y)}\n'
-                f'Last cursor position: {pos}',
+            f'Last cursor position: {pos}',
-            )
+        )
 
-    def get_screen_line(self, n):
+    def _get_screen_line(self, n):
         return self.screenshot().splitlines()[n]
 
-    def get_cursor_line(self):
+    def _get_cursor_line(self):
         _, y = self._get_cursor_position()
-        return self.get_screen_line(y)
+        return self._get_screen_line(y)
 
     @contextlib.contextmanager
     def resize(self, width, height):
@@ -122,16 +112,13 @@ class PrintsErrorRunner(Runner):
         self.press(s)
         self.press('Enter')
 
+    def answer_no_if_modified(self):
+        if '*' in self._get_screen_line(0):
+            self.press('n')
 
-@contextlib.contextmanager
+    def run(self, callback):
-def run(*args, color=True, **kwargs):
+        # this is a bit of a hack, the in-process fake defers all execution
-    cmd = (sys.executable, '-mcoverage', 'run', '-m', 'babi', *args)
+        callback()
-    quoted = ' '.join(shlex.quote(p) for p in cmd)
-    term = 'screen-256color' if color else 'screen'
-    cmd = ('bash', '-c', f'export TERM={term}; exec {quoted}')
-    with PrintsErrorRunner(*cmd, **kwargs) as h:
-        h.await_text(babi.VERSION_STR)
-        yield h
 
 
 @contextlib.contextmanager
@@ -139,9 +126,7 @@ def and_exit(h):
     yield
     # only try and exit in non-exceptional cases
     h.press('^X')
-    # dismiss the save prompt
+    h.answer_no_if_modified()
-    if ' *' in h.get_screen_line(0):
-        h.press('n')
     h.await_exit()
 
 

tests/color_test.py

@@ -1,15 +1,14 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-@pytest.mark.parametrize('color', (True, False))
+@pytest.mark.parametrize('colors', (8, 256))
-def test_color_test(color):
+def test_color_test(run, colors):
-    with run('--color-test', color=color) as h, and_exit(h):
+    with run('--color-test', colors=colors) as h, and_exit(h):
         h.await_text('*  1*  2')
 
 
-def test_can_start_without_color():
+def test_can_start_without_color(run):
-    with run(color=False) as h, and_exit(h):
+    with run(colors=8) as h, and_exit(h):
         pass

tests/command_mode_test.py

@@ -1,18 +1,17 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 from testing.runner import trigger_command_mode
 
 
-def test_quit_via_colon_q():
+def test_quit_via_colon_q(run):
     with run() as h:
         trigger_command_mode(h)
         h.press_and_enter(':q')
         h.await_exit()
 
 
-def test_key_navigation_in_command_mode():
+def test_key_navigation_in_command_mode(run):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press('hello world')
@@ -48,7 +47,7 @@ def test_key_navigation_in_command_mode():
 
 
 @pytest.mark.parametrize('key', ('BSpace', '^H'))
-def test_command_mode_backspace(key):
+def test_command_mode_backspace(run, key):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press('hello world')
@@ -65,7 +64,7 @@ def test_command_mode_backspace(key):
         h.press('^C')
 
 
-def test_command_mode_ctrl_k():
+def test_command_mode_ctrl_k(run):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press('hello world')
@@ -77,7 +76,7 @@ def test_command_mode_ctrl_k():
         h.press('Enter')
 
 
-def test_command_mode_control_left():
+def test_command_mode_control_left(run):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press('hello world')
@@ -95,7 +94,7 @@ def test_command_mode_control_left():
         h.press('^C')
 
 
-def test_command_mode_control_right():
+def test_command_mode_control_right(run):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press('hello world')
@@ -115,7 +114,7 @@ def test_command_mode_control_right():
         h.press('^C')
 
 
-def test_save_via_command_mode(tmpdir):
+def test_save_via_command_mode(run, tmpdir):
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
@@ -126,7 +125,7 @@ def test_save_via_command_mode(tmpdir):
     assert f.read() == 'hello world\n'
 
 
-def test_repeated_command_mode_does_not_show_previous_command(tmpdir):
+def test_repeated_command_mode_does_not_show_previous_command(run, tmpdir):
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
@@ -138,7 +137,7 @@ def test_repeated_command_mode_does_not_show_previous_command(tmpdir):
         h.press('Enter')
 
 
-def test_write_and_quit(tmpdir):
+def test_write_and_quit(run, tmpdir):
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
@@ -150,7 +149,7 @@ def test_write_and_quit(tmpdir):
     assert f.read() == 'hello world\n'
 
 
-def test_resizing_and_scrolling_in_command_mode():
+def test_resizing_and_scrolling_in_command_mode(run):
     with run(width=20) as h, and_exit(h):
         h.press('a' * 15)
         h.await_text(f'\n{"a" * 15}\n')
@@ -169,14 +168,14 @@ def test_resizing_and_scrolling_in_command_mode():
         h.press('Enter')
 
 
-def test_invalid_command():
+def test_invalid_command(run):
     with run() as h, and_exit(h):
         trigger_command_mode(h)
         h.press_and_enter(':fake')
         h.await_text('invalid command: :fake')
 
 
-def test_empty_command_is_noop():
+def test_empty_command_is_noop(run):
     with run() as h, and_exit(h):
         h.press('hello ')
         trigger_command_mode(h)
@@ -186,7 +185,7 @@ def test_empty_command_is_noop():
         h.await_text_missing('invalid command')
 
 
-def test_cancel_command_mode():
+def test_cancel_command_mode(run):
     with run() as h, and_exit(h):
         h.press('hello ')
         trigger_command_mode(h)

tests/conftest.py

@@ -1,8 +1,18 @@
+import contextlib
+import curses
 import os
+import shlex
+import sys
+from typing import Callable
+from typing import NamedTuple
+from typing import Union
 from unittest import mock
 
 import pytest
 
+import babi
+from testing.runner import PrintsErrorRunner
+
 
 @pytest.fixture(autouse=True)
 def xdg_data_home(tmpdir):
@@ -15,4 +25,358 @@ def xdg_data_home(tmpdir):
 def ten_lines(tmpdir):
     f = tmpdir.join('f')
     f.write('\n'.join(f'line_{i}' for i in range(10)))
-    yield f
+    return f
+
+
+class Screen:
+    def __init__(self, width, height):
+        self.disabled = True
+        self.width = width
+        self.height = height
+        self.lines = [' ' * self.width for _ in range(self.height)]
+        self.x = self.y = 0
+        self._prev_screenshot = None
+
+    def screenshot(self):
+        ret = ''.join(f'{line.rstrip()}\n' for line in self.lines)
+        if ret != self._prev_screenshot:
+            print('=' * 79)
+            print(ret, end='')
+            print('=' * 79)
+            self._prev_screenshot = ret
+        return ret
+
+    def addstr(self, y, x, s):
+        line = self.lines[y]
+        self.lines[y] = line[:x] + s + line[x + len(s):]
+
+    def insstr(self, y, x, s):
+        line = self.lines[y]
+        self.lines[y] = (line[:x] + s + line[x:])[:self.width]
+
+    def move(self, y, x):
+        print(f'MOVE: y: {y}, x: {x}')
+        self.y, self.x = y, x
+
+    def resize(self, *, width, height):
+        if height > self.height:
+            self.lines.extend([''] * (height - self.height))
+        else:
+            self.lines = self.lines[:height]
+        if width > self.width:
+            self.lines[:] = [line.ljust(width) for line in self.lines]
+        else:
+            self.lines[:] = [line[:width] for line in self.lines]
+        self.width, self.height = width, height
+
+
+class AwaitText(NamedTuple):
+    text: str
+
+    def __call__(self, screen):
+        if self.text not in screen.screenshot():
+            raise AssertionError(f'expected: {self.text!r}')
+
+
+class AwaitTextMissing(NamedTuple):
+    text: str
+
+    def __call__(self, screen):
+        if self.text in screen.screenshot():
+            raise AssertionError(f'expected missing: {self.text!r}')
+
+
+class AwaitCursorPosition(NamedTuple):
+    x: int
+    y: int
+
+    def __call__(self, screen):
+        assert (self.x, self.y) == (screen.x, screen.y)
+
+
+class AssertCursorLineEquals(NamedTuple):
+    line: str
+
+    def __call__(self, screen):
+        assert screen.lines[screen.y].rstrip() == self.line
+
+
+class AssertScreenLineEquals(NamedTuple):
+    n: int
+    line: str
+
+    def __call__(self, screen):
+        assert screen.lines[self.n].rstrip() == self.line
+
+
+class AssertFullContents(NamedTuple):
+    contents: str
+
+    def __call__(self, screen):
+        assert screen.screenshot() == self.contents
+
+
+class Resize(NamedTuple):
+    width: int
+    height: int
+
+    def __call__(self, screen):
+        screen.resize(width=self.width, height=self.height)
+
+
+class KeyPress(NamedTuple):
+    wch: Union[int, str]
+
+    def __call__(self, screen):
+        raise AssertionError('unreachable')
+
+
+class CursesError(NamedTuple):
+    def __call__(self, screen):
+        raise curses.error()
+
+
+class CursesScreen:
+    def __init__(self, runner):
+        self._runner = runner
+
+    def keypad(self, val):
+        pass
+
+    def addstr(self, y, x, s, attr=0):
+        self._runner.screen.addstr(y, x, s)
+
+    def insstr(self, y, x, s, attr=0):
+        self._runner.screen.insstr(y, x, s)
+
+    def move(self, y, x):
+        self._runner.screen.move(y, x)
+
+    def get_wch(self):
+        return self._runner._get_wch()
+
+    def chgat(self, y, x, n, color):
+        pass
+
+    def nodelay(self, val):
+        pass
+
+
+class Key(NamedTuple):
+    tmux: str
+    curses: bytes
+    wch: Union[int, str]
+
+    @property
+    def value(self) -> int:
+        return self.wch if isinstance(self.wch, int) else ord(self.wch)
+
+
+KEYS = [
+    Key('Enter', b'^M', '\r'),
+    Key('Tab', b'^I', '\t'),
+    Key('BTab', b'KEY_BTAB', curses.KEY_BTAB),
+    Key('DC', b'KEY_DC', curses.KEY_DC),
+    Key('BSpace', b'KEY_BACKSPACE', curses.KEY_BACKSPACE),
+    Key('Up', b'KEY_UP', curses.KEY_UP),
+    Key('Down', b'KEY_DOWN', curses.KEY_DOWN),
+    Key('Right', b'KEY_RIGHT', curses.KEY_RIGHT),
+    Key('Left', b'KEY_LEFT', curses.KEY_LEFT),
+    Key('Home', b'KEY_HOME', curses.KEY_HOME),
+    Key('End', b'KEY_END', curses.KEY_END),
+    Key('PageUp', b'KEY_PPAGE', curses.KEY_PPAGE),
+    Key('PageDown', b'KEY_NPAGE', curses.KEY_NPAGE),
+    Key('^Up', b'kUP5', 566),
+    Key('^Down', b'kDN5', 525),
+    Key('^Right', b'kRIT5', 560),
+    Key('^Left', b'kLFT5', 545),
+    Key('^Home', b'kHOM5', 535),
+    Key('^End', b'kEND5', 530),
+    Key('M-Right', b'kRIT3', 558),
+    Key('M-Left', b'kLFT3', 543),
+    Key('S-Up', b'KEY_SR', curses.KEY_SR),
+    Key('S-Down', b'KEY_SF', curses.KEY_SF),
+    Key('S-Right', b'KEY_SRIGHT', curses.KEY_SRIGHT),
+    Key('S-Left', b'KEY_SLEFT', curses.KEY_SLEFT),
+    Key('S-Home', b'KEY_SHOME', curses.KEY_SHOME),
+    Key('S-End', b'KEY_SEND', curses.KEY_SEND),
+    Key('^A', b'^A', '\x01'),
+    Key('^C', b'^C', '\x03'),
+    Key('^H', b'^H', '\x08'),
+    Key('^K', b'^K', '\x0b'),
+    Key('^E', b'^E', '\x05'),
+    Key('^J', b'^J', '\n'),
+    Key('^O', b'^O', '\x0f'),
+    Key('^R', b'^R', '\x12'),
+    Key('^S', b'^S', '\x13'),
+    Key('^U', b'^U', '\x15'),
+    Key('^V', b'^V', '\x16'),
+    Key('^W', b'^W', '\x17'),
+    Key('^X', b'^X', '\x18'),
+    Key('^Y', b'^Y', '\x19'),
+    Key('^[', b'^[', '\x1b'),
+    Key('^_', b'^_', '\x1f'),
+    Key('^\\', b'^\\', '\x1c'),
+    Key('!resize', b'KEY_RESIZE', curses.KEY_RESIZE),
+]
+KEYS_TMUX = {k.tmux: k.value for k in KEYS}
+KEYS_CURSES = {k.value: k.curses for k in KEYS}
+
+
+class DeferredRunner:
+    def __init__(self, command, width=80, height=24, colors=256):
+        self.command = command
+        self._i = 0
+        self._ops: Callable[[Screen], None] = []
+        self.screen = Screen(width, height)
+        self._colors = colors
+
+    def _get_wch(self):
+        while not isinstance(self._ops[self._i], KeyPress):
+            self._i += 1
+            self._ops[self._i - 1](self.screen)
+        self._i += 1
+        print(f'KEY: {self._ops[self._i - 1].wch!r}')
+        return self._ops[self._i - 1].wch
+
+    def await_text(self, text):
+        self._ops.append(AwaitText(text))
+
+    def await_text_missing(self, text):
+        self._ops.append(AwaitTextMissing(text))
+
+    def await_cursor_position(self, *, x, y):
+        self._ops.append(AwaitCursorPosition(x, y))
+
+    def assert_cursor_line_equals(self, line):
+        self._ops.append(AssertCursorLineEquals(line))
+
+    def assert_screen_line_equals(self, n, line):
+        self._ops.append(AssertScreenLineEquals(n, line))
+
+    def assert_full_contents(self, contents):
+        self._ops.append(AssertFullContents(contents))
+
+    def run(self, callback):
+        self._ops.append(lambda screen: callback())
+
+    def _expand_key(self, s):
+        if s == 'Escape':
+            return [KeyPress('\x1b'), CursesError()]
+        elif s in KEYS_TMUX:
+            return [KeyPress(KEYS_TMUX[s])]
+        elif s.startswith('^') and len(s) > 1 and s[1].isupper():
+            raise AssertionError(f'unknown key {s}')
+        elif s.startswith('M-'):
+            return [KeyPress('\x1b'), KeyPress(s[2:]), CursesError()]
+        else:
+            return [KeyPress(k) for k in s]
+
+    def press(self, s):
+        self._ops.extend(self._expand_key(s))
+
+    def press_and_enter(self, s):
+        self.press(s)
+        self.press('Enter')
+
+    def answer_no_if_modified(self):
+        self._ops.append(KeyPress('n'))
+
+    @contextlib.contextmanager
+    def resize(self, *, width, height):
+        orig_width, orig_height = self.screen.width, self.screen.height
+        self._ops.append(Resize(width, height))
+        self._ops.append(KeyPress(curses.KEY_RESIZE))
+        try:
+            yield
+        finally:
+            self._ops.append(Resize(orig_width, orig_height))
+            self._ops.append(KeyPress(curses.KEY_RESIZE))
+
+    def _curses__noop(self, *_, **__):
+        pass
+
+    _curses_cbreak = _curses_init_pair = _curses_noecho = _curses__noop
+    _curses_nonl = _curses_raw = _curses_start_color = _curses__noop
+    _curses_use_default_colors = _curses__noop
+
+    _curses_error = curses.error  # so we don't mock the exception
+
+    def _curses_color_pair(self, n):
+        return 0
+
+    def _curses_keyname(self, k):
+        return KEYS_CURSES.get(k, b'')
+
+    def _curses_update_lines_cols(self):
+        curses.LINES = self.screen.height
+        curses.COLS = self.screen.width
+
+    def _curses_initscr(self):
+        curses.COLORS = self._colors
+        self._curses_update_lines_cols()
+        self.screen.enabled = True
+        return CursesScreen(self)
+
+    def _curses_endwin(self):
+        self.screen.disabled = True
+
+    def _curses_not_implemented(self, fn):
+        def fn_inner(*args, **kwargs):
+            raise NotImplementedError(fn)
+        return fn_inner
+
+    def _patch_curses(self):
+        patches = {
+            k: getattr(self, f'_curses_{k}', self._curses_not_implemented(k))
+            for k in dir(curses)
+            if not k.startswith('_') and callable(getattr(curses, k))
+        }
+        return mock.patch.multiple(curses, **patches)
+
+    def await_exit(self):
+        with self._patch_curses():
+            babi.main(self.command)
+        # we have already exited -- check remaining things
+        # KeyPress with failing condition or error
+        for i in range(self._i, len(self._ops)):
+            if self._ops[i] != KeyPress('n'):
+                raise AssertionError(self.ops[i:])
+
+
+@contextlib.contextmanager
+def screenshot_on_assert(h):
+    try:
+        yield h
+    except AssertionError:  # pragma: no cover
+        h.screenshot()
+        raise
+
+
+@contextlib.contextmanager
+def run_fake(*cmd, **kwargs):
+    h = DeferredRunner(cmd, **kwargs)
+    with screenshot_on_assert(h):
+        h.await_text(babi.VERSION_STR)
+        yield h
+
+
+@contextlib.contextmanager
+def run_tmux(*args, colors=256, **kwargs):
+    cmd = (sys.executable, '-mcoverage', 'run', '-m', 'babi', *args)
+    quoted = ' '.join(shlex.quote(p) for p in cmd)
+    term = 'screen-256color' if colors == 256 else 'screen'
+    cmd = ('bash', '-c', f'export TERM={term}; exec {quoted}')
+    with PrintsErrorRunner(*cmd, **kwargs) as h, screenshot_on_assert(h):
+        # startup with coverage can be slow
+        h.await_text(babi.VERSION_STR, timeout=2)
+        yield h
+
+
+@pytest.fixture(
+    scope='session',
+    params=[run_fake, run_tmux],
+    ids=['fake', 'tmux'],
+)
+def run(request):
+    return request.param

tests/current_position_test.py

@@ -1,8 +1,7 @@
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_current_position(ten_lines):
+def test_current_position(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^C')
         h.await_text('line 1, col 1 (of 10 lines)')

tests/cut_uncut_test.py

@@ -1,8 +1,7 @@
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_cut_and_uncut(ten_lines):
+def test_cut_and_uncut(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^K')
         h.await_text_missing('line_0')
@@ -18,7 +17,7 @@ def test_cut_and_uncut(ten_lines):
         h.await_text('line_0')
 
 
-def test_cut_at_beginning_of_file():
+def test_cut_at_beginning_of_file(run):
     with run() as h, and_exit(h):
         h.press('^K')
         h.press('^K')
@@ -26,7 +25,7 @@ def test_cut_at_beginning_of_file():
         h.await_text_missing('*')
 
 
-def test_cut_end_of_file():
+def test_cut_end_of_file(run):
     with run() as h, and_exit(h):
         h.press('hi')
         h.press('Down')
@@ -34,7 +33,7 @@ def test_cut_end_of_file():
         h.press('hi')
 
 
-def test_cut_uncut_multiple_file_buffers(tmpdir):
+def test_cut_uncut_multiple_file_buffers(run, tmpdir):
     f1 = tmpdir.join('f1')
     f1.write('hello\nworld\n')
     f2 = tmpdir.join('f2')
@@ -50,7 +49,7 @@ def test_cut_uncut_multiple_file_buffers(tmpdir):
         h.await_text('hello\ngood\nbye\n')
 
 
-def test_selection_cut_uncut(ten_lines):
+def test_selection_cut_uncut(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Right')
         h.press('S-Right')
@@ -65,7 +64,7 @@ def test_selection_cut_uncut(ten_lines):
         h.await_text('line_0\nline_1')
 
 
-def test_selection_cut_uncut_backwards_select(ten_lines):
+def test_selection_cut_uncut_backwards_select(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         for _ in range(3):
             h.press('Down')
@@ -85,7 +84,7 @@ def test_selection_cut_uncut_backwards_select(ten_lines):
         h.await_cursor_position(x=1, y=4)
 
 
-def test_selection_cut_uncut_within_line(ten_lines):
+def test_selection_cut_uncut_within_line(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Right')
         h.press('S-Right')
@@ -101,7 +100,7 @@ def test_selection_cut_uncut_within_line(ten_lines):
         h.await_cursor_position(x=3, y=1)
 
 
-def test_selection_cut_uncut_selection_offscreen_y(ten_lines):
+def test_selection_cut_uncut_selection_offscreen_y(run, ten_lines):
     with run(str(ten_lines), height=4) as h, and_exit(h):
         for _ in range(3):
             h.press('S-Down')
@@ -112,7 +111,7 @@ def test_selection_cut_uncut_selection_offscreen_y(ten_lines):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_selection_cut_uncut_selection_offscreen_x():
+def test_selection_cut_uncut_selection_offscreen_x(run):
     with run() as h, and_exit(h):
         h.press(f'hello{"o" * 100}')
         h.await_text_missing('hello')

tests/go_to_line_test.py

@@ -1,10 +1,9 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_prompt_window_width():
+def test_prompt_window_width(run):
     with run() as h, and_exit(h):
         h.press('^_')
         h.await_text('enter line number:')
@@ -20,7 +19,7 @@ def test_prompt_window_width():
         h.press('Enter')
 
 
-def test_go_to_line_line(ten_lines):
+def test_go_to_line_line(run, ten_lines):
     def _jump_to_line(n):
         h.press('^_')
         h.await_text('enter line number:')
@@ -37,19 +36,19 @@ def test_go_to_line_line(ten_lines):
         # should go to end of the file
         _jump_to_line(999)
         h.await_cursor_position(x=0, y=4)
-        assert h.get_screen_line(3) == 'line_9'
+        h.assert_screen_line_equals(3, 'line_9')
         # should also go to the end of the file
         _jump_to_line(-1)
         h.await_cursor_position(x=0, y=4)
-        assert h.get_screen_line(3) == 'line_9'
+        h.assert_screen_line_equals(3, 'line_9')
         # should go to beginning of file
         _jump_to_line(-999)
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_0'
+        h.assert_cursor_line_equals('line_0')
 
 
 @pytest.mark.parametrize('key', ('Enter', '^C'))
-def test_go_to_line_cancel(ten_lines, key):
+def test_go_to_line_cancel(run, ten_lines, key):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
@@ -61,7 +60,7 @@ def test_go_to_line_cancel(ten_lines, key):
         h.await_text('cancelled')
 
 
-def test_go_to_line_not_an_integer():
+def test_go_to_line_not_an_integer(run):
     with run() as h, and_exit(h):
         h.press('^_')
         h.await_text('enter line number:')

tests/indent_test.py

@@ -1,8 +1,7 @@
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_indent_at_beginning_of_line():
+def test_indent_at_beginning_of_line(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.press('Home')
@@ -11,7 +10,7 @@ def test_indent_at_beginning_of_line():
         h.await_cursor_position(x=4, y=1)
 
 
-def test_indent_not_full_tab():
+def test_indent_not_full_tab(run):
     with run() as h, and_exit(h):
         h.press('h')
         h.press('Tab')
@@ -20,14 +19,14 @@ def test_indent_not_full_tab():
         h.await_cursor_position(x=8, y=1)
 
 
-def test_indent_fixes_eof():
+def test_indent_fixes_eof(run):
     with run() as h, and_exit(h):
         h.press('Tab')
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
 
 
-def test_indent_selection(ten_lines):
+def test_indent_selection(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('S-Right')
         h.press('Tab')
@@ -37,7 +36,7 @@ def test_indent_selection(ten_lines):
         h.await_text('\nine_0\n')
 
 
-def test_indent_selection_does_not_extend_mid_line_selection(ten_lines):
+def test_indent_selection_does_not_extend_mid_line_selection(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Right')
         h.press('S-Right')
@@ -48,7 +47,7 @@ def test_indent_selection_does_not_extend_mid_line_selection(ten_lines):
         h.await_text('\n    lne_0\n')
 
 
-def test_indent_selection_leaves_blank_lines(tmpdir):
+def test_indent_selection_leaves_blank_lines(run, tmpdir):
     f = tmpdir.join('f')
     f.write('1\n\n2\n\n3\n')
     with run(str(f)) as h, and_exit(h):
@@ -59,7 +58,7 @@ def test_indent_selection_leaves_blank_lines(tmpdir):
     assert f.read() == '    1\n\n    2\n\n3\n'
 
 
-def test_dedent_no_indentation():
+def test_dedent_no_indentation(run):
     with run() as h, and_exit(h):
         h.press('a')
         h.press('BTab')
@@ -67,7 +66,7 @@ def test_dedent_no_indentation():
         h.await_cursor_position(x=1, y=1)
 
 
-def test_dedent_exactly_one_indent():
+def test_dedent_exactly_one_indent(run):
     with run() as h, and_exit(h):
         h.press('Tab')
         h.press('a')
@@ -77,7 +76,7 @@ def test_dedent_exactly_one_indent():
         h.await_cursor_position(x=1, y=1)
 
 
-def test_dedent_selection(tmpdir):
+def test_dedent_selection(run, tmpdir):
     f = tmpdir.join('f')
     f.write('1\n  2\n        3\n')
     with run(str(f)) as h, and_exit(h):
@@ -87,7 +86,7 @@ def test_dedent_selection(tmpdir):
         h.await_text('\n1\n2\n    3\n')
 
 
-def test_dedent_selection_does_not_make_selection_negative():
+def test_dedent_selection_does_not_make_selection_negative(run):
     with run() as h, and_exit(h):
         h.press('Tab')
         h.press('hello')

tests/movement_test.py

@@ -1,10 +1,9 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_arrow_key_movement(tmpdir):
+def test_arrow_key_movement(run, tmpdir):
     f = tmpdir.join('f')
     f.write(
         'short\n'
@@ -63,7 +62,7 @@ def test_arrow_key_movement(tmpdir):
     ('page_up', 'page_down'),
     (('PageUp', 'PageDown'), ('^Y', '^V')),
 )
-def test_page_up_and_page_down(ten_lines, page_up, page_down):
+def test_page_up_and_page_down(run, ten_lines, page_up, page_down):
     with run(str(ten_lines), height=10) as h, and_exit(h):
         h.press('Down')
         h.press('Down')
@@ -73,37 +72,37 @@ def test_page_up_and_page_down(ten_lines, page_up, page_down):
         h.press(page_down)
         h.await_text('line_8')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_6'
+        h.assert_cursor_line_equals('line_6')
 
         h.press(page_up)
         h.await_text_missing('line_8')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_0'
+        h.assert_cursor_line_equals('line_0')
 
         h.press(page_down)
         h.press(page_down)
         h.await_cursor_position(x=0, y=5)
-        assert h.get_cursor_line() == ''
+        h.assert_cursor_line_equals('')
         h.press('Up')
         h.await_cursor_position(x=0, y=4)
-        assert h.get_cursor_line() == 'line_9'
+        h.assert_cursor_line_equals('line_9')
 
 
-def test_page_up_page_down_size_small_window(ten_lines):
+def test_page_up_page_down_size_small_window(run, ten_lines):
     with run(str(ten_lines), height=4) as h, and_exit(h):
         h.press('PageDown')
         h.await_text('line_2')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_1'
+        h.assert_cursor_line_equals('line_1')
 
         h.press('Down')
         h.press('PageUp')
         h.await_text_missing('line_2')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_0'
+        h.assert_cursor_line_equals('line_0')
 
 
-def test_ctrl_home(ten_lines):
+def test_ctrl_home(run, ten_lines):
     with run(str(ten_lines), height=4) as h, and_exit(h):
         for _ in range(3):
             h.press('PageDown')
@@ -114,14 +113,14 @@ def test_ctrl_home(ten_lines):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_ctrl_end(ten_lines):
+def test_ctrl_end(run, ten_lines):
     with run(str(ten_lines), height=6) as h, and_exit(h):
         h.press('^End')
         h.await_cursor_position(x=0, y=3)
-        assert h.get_screen_line(2) == 'line_9'
+        h.assert_screen_line_equals(2, 'line_9')
 
 
-def test_ctrl_end_already_on_last_page(ten_lines):
+def test_ctrl_end_already_on_last_page(run, ten_lines):
     with run(str(ten_lines), height=9) as h, and_exit(h):
         h.press('PageDown')
         h.await_cursor_position(x=0, y=1)
@@ -129,10 +128,10 @@ def test_ctrl_end_already_on_last_page(ten_lines):
 
         h.press('^End')
         h.await_cursor_position(x=0, y=6)
-        assert h.get_screen_line(5) == 'line_9'
+        h.assert_screen_line_equals(5, 'line_9')
 
 
-def test_scrolling_arrow_key_movement(ten_lines):
+def test_scrolling_arrow_key_movement(run, ten_lines):
     with run(str(ten_lines), height=10) as h, and_exit(h):
         h.await_text('line_7')
         # we should not have scrolled after 7 presses
@@ -144,7 +143,7 @@ def test_scrolling_arrow_key_movement(ten_lines):
         h.press('Down')
         h.await_text('line_8')
         h.await_cursor_position(x=0, y=4)
-        assert h.get_cursor_line() == 'line_8'
+        h.assert_cursor_line_equals('line_8')
         # we should not have scrolled after 3 up presses
         for _ in range(3):
             h.press('Up')
@@ -154,15 +153,15 @@ def test_scrolling_arrow_key_movement(ten_lines):
         h.await_text('line_0')
 
 
-def test_ctrl_down_beginning_of_file(ten_lines):
+def test_ctrl_down_beginning_of_file(run, ten_lines):
     with run(str(ten_lines), height=5) as h, and_exit(h):
         h.press('^Down')
         h.await_text('line_3')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_1'
+        h.assert_cursor_line_equals('line_1')
 
 
-def test_ctrl_up_moves_screen_up_one_line(ten_lines):
+def test_ctrl_up_moves_screen_up_one_line(run, ten_lines):
     with run(str(ten_lines), height=5) as h, and_exit(h):
         h.press('^Down')
         h.press('^Up')
@@ -171,7 +170,7 @@ def test_ctrl_up_moves_screen_up_one_line(ten_lines):
         h.await_cursor_position(x=0, y=2)
 
 
-def test_ctrl_up_at_beginning_of_file_does_nothing(ten_lines):
+def test_ctrl_up_at_beginning_of_file_does_nothing(run, ten_lines):
     with run(str(ten_lines), height=5) as h, and_exit(h):
         h.press('^Up')
         h.await_text('line_0')
@@ -179,7 +178,7 @@ def test_ctrl_up_at_beginning_of_file_does_nothing(ten_lines):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_ctrl_up_at_bottom_of_screen(ten_lines):
+def test_ctrl_up_at_bottom_of_screen(run, ten_lines):
     with run(str(ten_lines), height=5) as h, and_exit(h):
         h.press('^Down')
         h.press('Down')
@@ -192,17 +191,17 @@ def test_ctrl_up_at_bottom_of_screen(ten_lines):
         h.await_cursor_position(x=0, y=3)
 
 
-def test_ctrl_down_at_end_of_file(ten_lines):
+def test_ctrl_down_at_end_of_file(run, ten_lines):
     with run(str(ten_lines), height=5) as h, and_exit(h):
         h.press('^End')
         for i in range(4):
             h.press('^Down')
         h.press('Up')
         h.await_text('line_9')
-        assert h.get_cursor_line() == 'line_9'
+        h.assert_cursor_line_equals('line_9')
 
 
-def test_ctrl_down_causing_cursor_movement_should_fix_x(tmpdir):
+def test_ctrl_down_causing_cursor_movement_should_fix_x(run, tmpdir):
     f = tmpdir.join('f')
     f.write('line_1\n\nline_2\n\nline_3\n\nline_4\n')
 
@@ -213,7 +212,7 @@ def test_ctrl_down_causing_cursor_movement_should_fix_x(tmpdir):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_ctrl_up_causing_cursor_movement_should_fix_x(tmpdir):
+def test_ctrl_up_causing_cursor_movement_should_fix_x(run, tmpdir):
     f = tmpdir.join('f')
     f.write('line_1\n\nline_2\n\nline_3\n\nline_4\n')
 
@@ -230,7 +229,7 @@ def test_ctrl_up_causing_cursor_movement_should_fix_x(tmpdir):
 
 
 @pytest.mark.parametrize('k', ('End', '^E'))
-def test_end_key(tmpdir, k):
+def test_end_key(run, tmpdir, k):
     f = tmpdir.join('f')
     f.write('hello world\nhello world\n')
 
@@ -244,7 +243,7 @@ def test_end_key(tmpdir, k):
 
 
 @pytest.mark.parametrize('k', ('Home', '^A'))
-def test_home_key(tmpdir, k):
+def test_home_key(run, tmpdir, k):
     f = tmpdir.join('f')
     f.write('hello world\nhello world\n')
 
@@ -259,14 +258,14 @@ def test_home_key(tmpdir, k):
         h.await_cursor_position(x=0, y=2)
 
 
-def test_page_up_does_not_go_negative(ten_lines):
+def test_page_up_does_not_go_negative(run, ten_lines):
     with run(str(ten_lines), height=10) as h, and_exit(h):
         for _ in range(8):
             h.press('Down')
         h.await_cursor_position(x=0, y=4)
         h.press('^Y')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'line_0'
+        h.assert_cursor_line_equals('line_0')
 
 
 @pytest.fixture
@@ -283,7 +282,7 @@ hi
     yield f
 
 
-def test_ctrl_right_jump_by_word(jump_word_file):
+def test_ctrl_right_jump_by_word(run, jump_word_file):
     with run(str(jump_word_file)) as h, and_exit(h):
         h.press('^Right')
         h.await_cursor_position(x=5, y=1)
@@ -308,7 +307,7 @@ def test_ctrl_right_jump_by_word(jump_word_file):
         h.await_cursor_position(x=0, y=6)
 
 
-def test_ctrl_left_jump_by_word(jump_word_file):
+def test_ctrl_left_jump_by_word(run, jump_word_file):
     with run(str(jump_word_file)) as h, and_exit(h):
         h.press('^Left')
         h.await_cursor_position(x=0, y=1)
@@ -329,16 +328,16 @@ def test_ctrl_left_jump_by_word(jump_word_file):
         h.await_cursor_position(x=2, y=3)
 
 
-def test_ctrl_right_triggering_scroll(jump_word_file):
+def test_ctrl_right_triggering_scroll(run, jump_word_file):
     with run(str(jump_word_file), height=4) as h, and_exit(h):
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
         h.press('^Right')
         h.await_cursor_position(x=0, y=1)
-        assert h.get_cursor_line() == 'hi'
+        h.assert_cursor_line_equals('hi')
 
 
-def test_ctrl_left_triggering_scroll(jump_word_file):
+def test_ctrl_left_triggering_scroll(run, jump_word_file):
     with run(str(jump_word_file)) as h, and_exit(h):
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
@@ -346,4 +345,4 @@ def test_ctrl_left_triggering_scroll(jump_word_file):
         h.await_cursor_position(x=0, y=1)
         h.press('^Left')
         h.await_cursor_position(x=11, y=1)
-        assert h.get_cursor_line() == 'hello world'
+        h.assert_cursor_line_equals('hello world')

tests/multiple_files_test.py

@@ -1,7 +1,4 @@
-from testing.runner import run
+def test_multiple_files(run, tmpdir):
-
-
-def test_multiple_files(tmpdir):
     a = tmpdir.join('file_a')
     a.write('a text')
     b = tmpdir.join('file_b')

tests/replace_test.py

@@ -1,11 +1,10 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
 @pytest.mark.parametrize('key', ('^C', 'Enter'))
-def test_replace_cancel(key):
+def test_replace_cancel(run, key):
     with run() as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -13,7 +12,7 @@ def test_replace_cancel(key):
         h.await_text('cancelled')
 
 
-def test_replace_invalid_regex():
+def test_replace_invalid_regex(run):
     with run() as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -21,7 +20,7 @@ def test_replace_invalid_regex():
         h.await_text("invalid regex: '('")
 
 
-def test_replace_cancel_at_replace_string():
+def test_replace_cancel_at_replace_string(run):
     with run() as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -31,7 +30,7 @@ def test_replace_cancel_at_replace_string():
         h.await_text('cancelled')
 
 
-def test_replace_actual_contents(ten_lines):
+def test_replace_actual_contents(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -46,7 +45,7 @@ def test_replace_actual_contents(ten_lines):
         h.await_text('replaced 1 occurrence')
 
 
-def test_replace_sets_x_hint_properly(tmpdir):
+def test_replace_sets_x_hint_properly(run, tmpdir):
     f = tmpdir.join('f')
     contents = '''\
 beginning_line
@@ -68,7 +67,7 @@ match me!
         h.await_cursor_position(x=6, y=1)
 
 
-def test_replace_cancel_at_individual_replace(ten_lines):
+def test_replace_cancel_at_individual_replace(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -80,7 +79,7 @@ def test_replace_cancel_at_individual_replace(ten_lines):
         h.await_text('cancelled')
 
 
-def test_replace_unknown_characters_at_individual_replace(ten_lines):
+def test_replace_unknown_characters_at_individual_replace(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -93,7 +92,7 @@ def test_replace_unknown_characters_at_individual_replace(ten_lines):
         h.await_text('cancelled')
 
 
-def test_replace_say_no_to_individual_replace(ten_lines):
+def test_replace_say_no_to_individual_replace(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -110,7 +109,7 @@ def test_replace_say_no_to_individual_replace(ten_lines):
         h.await_text('replaced 2 occurrences')
 
 
-def test_replace_all(ten_lines):
+def test_replace_all(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -124,7 +123,7 @@ def test_replace_all(ten_lines):
         h.await_text('replaced 10 occurrences')
 
 
-def test_replace_with_empty_string(ten_lines):
+def test_replace_with_empty_string(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -136,7 +135,7 @@ def test_replace_with_empty_string(ten_lines):
         h.await_text_missing('line_1')
 
 
-def test_replace_search_not_found(ten_lines):
+def test_replace_search_not_found(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -147,7 +146,7 @@ def test_replace_search_not_found(ten_lines):
         h.await_text('no matches')
 
 
-def test_replace_small_window_size(ten_lines):
+def test_replace_small_window_size(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -162,9 +161,10 @@ def test_replace_small_window_size(ten_lines):
         h.press('^C')
 
 
-def test_replace_height_1_highlight():
+def test_replace_height_1_highlight(run, tmpdir):
-    with run() as h, and_exit(h):
+    f = tmpdir.join('f')
-        h.press('x' * 90)
+    f.write('x' * 90)
+    with run(str(f)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
         h.press_and_enter('^x+$')
@@ -179,7 +179,7 @@ def test_replace_height_1_highlight():
         h.press('^C')
 
 
-def test_replace_line_goes_off_screen():
+def test_replace_line_goes_off_screen(run):
     with run() as h, and_exit(h):
         h.press(f'{"a" * 20}{"b" * 90}')
         h.press('^A')
@@ -196,7 +196,7 @@ def test_replace_line_goes_off_screen():
         h.await_text('replaced 1 occurrence')
 
 
-def test_replace_undo_undoes_only_one(ten_lines):
+def test_replace_undo_undoes_only_one(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^\\')
         h.await_text('search (to replace):')
@@ -213,7 +213,7 @@ def test_replace_undo_undoes_only_one(ten_lines):
         h.await_text_missing('line_0')
 
 
-def test_replace_multiple_occurrences_in_line():
+def test_replace_multiple_occurrences_in_line(run):
     with run() as h, and_exit(h):
         h.press('baaaaabaaaaa')
         h.press('^\\')
@@ -226,7 +226,7 @@ def test_replace_multiple_occurrences_in_line():
         h.await_text('bqbq')
 
 
-def test_replace_after_wrapping(ten_lines):
+def test_replace_after_wrapping(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Down')
         h.press('^\\')
@@ -242,7 +242,7 @@ def test_replace_after_wrapping(ten_lines):
         h.await_text('replaced 2 occurrences')
 
 
-def test_replace_after_cursor_after_wrapping():
+def test_replace_after_cursor_after_wrapping(run):
     with run() as h, and_exit(h):
         h.press('baaab')
         h.press('Left')
@@ -258,7 +258,7 @@ def test_replace_after_cursor_after_wrapping():
         h.await_text('qaaab')
 
 
-def test_replace_separate_line_after_wrapping(ten_lines):
+def test_replace_separate_line_after_wrapping(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Down')
         h.press('Down')

tests/resize_test.py

@@ -1,9 +1,8 @@
 import babi
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_window_height_2(tmpdir):
+def test_window_height_2(run, tmpdir):
     # 2 tall:
     # - header is hidden, otherwise behaviour is normal
     f = tmpdir.join('f.txt')
@@ -12,16 +11,16 @@ def test_window_height_2(tmpdir):
     with run(str(f)) as h, and_exit(h):
         h.await_text('hello world')
 
-        with h.resize(80, 2):
+        with h.resize(width=80, height=2):
             h.await_text_missing(babi.VERSION_STR)
-            assert h.screenshot() == 'hello world\n\n'
+            h.assert_full_contents('hello world\n\n')
             h.press('^J')
             h.await_text('unknown key')
 
         h.await_text(babi.VERSION_STR)
 
 
-def test_window_height_1(tmpdir):
+def test_window_height_1(run, tmpdir):
     # 1 tall:
     # - only file contents as body
     # - status takes precedence over body, but cleared after single action
@@ -31,9 +30,9 @@ def test_window_height_1(tmpdir):
     with run(str(f)) as h, and_exit(h):
         h.await_text('hello world')
 
-        with h.resize(80, 1):
+        with h.resize(width=80, height=1):
             h.await_text_missing(babi.VERSION_STR)
-            assert h.screenshot() == 'hello world\n'
+            h.assert_full_contents('hello world\n')
             h.press('^J')
             h.await_text('unknown key')
             h.press('Right')
@@ -41,15 +40,15 @@ def test_window_height_1(tmpdir):
             h.press('Down')
 
 
-def test_reacts_to_resize():
+def test_reacts_to_resize(run):
     with run() as h, and_exit(h):
-        first_line = h.get_screen_line(0)
+        h.await_text('<<new file>>')
-        with h.resize(40, 20):
+        with h.resize(width=10, height=20):
-            # the first line should be different after resize
+            h.await_text_missing('<<new file>>')
-            h.await_text_missing(first_line)
+        h.await_text('<<new file>>')
 
 
-def test_resize_scrolls_up(ten_lines):
+def test_resize_scrolls_up(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.await_text('line_9')
 
@@ -58,37 +57,37 @@ def test_resize_scrolls_up(ten_lines):
         h.await_cursor_position(x=0, y=8)
 
         # a resize to a height of 10 should not scroll
-        with h.resize(80, 10):
+        with h.resize(width=80, height=10):
             h.await_text_missing('line_8')
             h.await_cursor_position(x=0, y=8)
 
         h.await_text('line_8')
 
         # but a resize to smaller should
-        with h.resize(80, 9):
+        with h.resize(width=80, height=9):
             h.await_text_missing('line_0')
             h.await_cursor_position(x=0, y=4)
             # make sure we're still on the same line
-            assert h.get_cursor_line() == 'line_7'
+            h.assert_cursor_line_equals('line_7')
 
 
-def test_resize_scroll_does_not_go_negative(ten_lines):
+def test_resize_scroll_does_not_go_negative(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         for _ in range(5):
             h.press('Down')
         h.await_cursor_position(x=0, y=6)
 
-        with h.resize(80, 7):
+        with h.resize(width=80, height=7):
             h.await_text_missing('line_9')
         h.await_text('line_9')
 
         for _ in range(3):
             h.press('Up')
 
-        assert h.get_screen_line(1) == 'line_0'
+        h.assert_screen_line_equals(1, 'line_0')
 
 
-def test_horizontal_scrolling(tmpdir):
+def test_horizontal_scrolling(run, tmpdir):
     f = tmpdir.join('f')
     lots_of_text = ''.join(
         ''.join(str(i) * 10 for i in range(10))
@@ -115,7 +114,7 @@ def test_horizontal_scrolling(tmpdir):
         h.await_text('1222»')
 
 
-def test_horizontal_scrolling_exact_width(tmpdir):
+def test_horizontal_scrolling_exact_width(run, tmpdir):
     f = tmpdir.join('f')
     f.write('0' * 80)
 
@@ -130,12 +129,12 @@ def test_horizontal_scrolling_exact_width(tmpdir):
         h.await_cursor_position(x=7, y=1)
 
 
-def test_horizontal_scrolling_narrow_window(tmpdir):
+def test_horizontal_scrolling_narrow_window(run, tmpdir):
     f = tmpdir.join('f')
     f.write(''.join(str(i) * 10 for i in range(10)))
 
     with run(str(f)) as h, and_exit(h):
-        with h.resize(5, 24):
+        with h.resize(width=5, height=24):
             h.await_text('0000»')
             for _ in range(3):
                 h.press('Right')
@@ -148,12 +147,12 @@ def test_horizontal_scrolling_narrow_window(tmpdir):
             h.await_text('«001»')
 
 
-def test_window_width_1(tmpdir):
+def test_window_width_1(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello')
 
     with run(str(f)) as h, and_exit(h):
-        with h.resize(1, 24):
+        with h.resize(width=1, height=24):
             h.await_text('»')
             for _ in range(3):
                 h.press('Right')
@@ -161,7 +160,7 @@ def test_window_width_1(tmpdir):
         h.await_cursor_position(x=3, y=1)
 
 
-def test_resize_while_cursor_at_bottom(tmpdir):
+def test_resize_while_cursor_at_bottom(run, tmpdir):
     f = tmpdir.join('f')
     f.write('x\n' * 35)
     with run(str(f), height=40) as h, and_exit(h):

tests/save_test.py

@@ -1,10 +1,9 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_mixed_newlines(tmpdir):
+def test_mixed_newlines(run, tmpdir):
     f = tmpdir.join('f')
     f.write_binary(b'foo\nbar\r\n')
     with run(str(f)) as h, and_exit(h):
@@ -13,20 +12,20 @@ def test_mixed_newlines(tmpdir):
         h.await_text(r"mixed newlines will be converted to '\n'")
 
 
-def test_new_file():
+def test_new_file(run):
     with run('this_is_a_new_file') as h, and_exit(h):
         h.await_text('this_is_a_new_file')
         h.await_text('(new file)')
 
 
-def test_not_a_file(tmpdir):
+def test_not_a_file(run, tmpdir):
     d = tmpdir.join('d').ensure_dir()
     with run(str(d)) as h, and_exit(h):
         h.await_text('<<new file>>')
         h.await_text("d' is not a file")
 
 
-def test_save_no_filename_specified(tmpdir):
+def test_save_no_filename_specified(run, tmpdir):
     f = tmpdir.join('f')
 
     with run() as h, and_exit(h):
@@ -36,11 +35,11 @@ def test_save_no_filename_specified(tmpdir):
         h.press_and_enter(str(f))
         h.await_text('saved! (1 line written)')
         h.await_text_missing('*')
-        assert f.read() == 'hello world\n'
+    assert f.read() == 'hello world\n'
 
 
 @pytest.mark.parametrize('k', ('Enter', '^C'))
-def test_save_no_filename_specified_cancel(k):
+def test_save_no_filename_specified_cancel(run, k):
     with run() as h, and_exit(h):
         h.press('hello world')
         h.press('^S')
@@ -49,22 +48,22 @@ def test_save_no_filename_specified_cancel(k):
         h.await_text('cancelled')
 
 
-def test_saving_file_on_disk_changes(tmpdir):
+def test_saving_file_on_disk_changes(run, tmpdir):
     # TODO: this should show some sort of diffing thing or just allow overwrite
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
-        f.write('hello world')
+        h.run(lambda: f.write('hello world'))
 
         h.press('^S')
         h.await_text('file changed on disk, not implemented')
 
 
-def test_allows_saving_same_contents_as_modified_contents(tmpdir):
+def test_allows_saving_same_contents_as_modified_contents(run, tmpdir):
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
-        f.write('hello world\n')
+        h.run(lambda: f.write('hello world\n'))
         h.press('hello world')
         h.await_text('hello world')
 
@@ -75,7 +74,7 @@ def test_allows_saving_same_contents_as_modified_contents(tmpdir):
     assert f.read() == 'hello world\n'
 
 
-def test_allows_saving_if_file_on_disk_does_not_change(tmpdir):
+def test_allows_saving_if_file_on_disk_does_not_change(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello world\n')
 
@@ -91,7 +90,7 @@ def test_allows_saving_if_file_on_disk_does_not_change(tmpdir):
     assert f.read() == 'ohai\nhello world\n'
 
 
-def test_save_file_when_it_did_not_exist(tmpdir):
+def test_save_file_when_it_did_not_exist(run, tmpdir):
     f = tmpdir.join('f')
 
     with run(str(f)) as h, and_exit(h):
@@ -103,7 +102,7 @@ def test_save_file_when_it_did_not_exist(tmpdir):
     assert f.read() == 'hello world\n'
 
 
-def test_save_via_ctrl_o(tmpdir):
+def test_save_via_ctrl_o(run, tmpdir):
     f = tmpdir.join('f')
     with run(str(f)) as h, and_exit(h):
         h.press('hello world')
@@ -111,10 +110,10 @@ def test_save_via_ctrl_o(tmpdir):
         h.await_text(f'enter filename: {f}')
         h.press('Enter')
         h.await_text('saved! (1 line written)')
-        assert f.read() == 'hello world\n'
+    assert f.read() == 'hello world\n'
 
 
-def test_save_via_ctrl_o_set_filename(tmpdir):
+def test_save_via_ctrl_o_set_filename(run, tmpdir):
     f = tmpdir.join('f')
     with run() as h, and_exit(h):
         h.press('hello world')
@@ -122,11 +121,11 @@ def test_save_via_ctrl_o_set_filename(tmpdir):
         h.await_text('enter filename:')
         h.press_and_enter(str(f))
         h.await_text('saved! (1 line written)')
-        assert f.read() == 'hello world\n'
+    assert f.read() == 'hello world\n'
 
 
 @pytest.mark.parametrize('key', ('^C', 'Enter'))
-def test_save_via_ctrl_o_cancelled(tmpdir, key):
+def test_save_via_ctrl_o_cancelled(run, tmpdir, key):
     with run() as h, and_exit(h):
         h.press('hello world')
         h.press('^O')
@@ -135,7 +134,7 @@ def test_save_via_ctrl_o_cancelled(tmpdir, key):
         h.await_text('cancelled')
 
 
-def test_save_on_exit_cancel_yn():
+def test_save_on_exit_cancel_yn(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.await_text('hello')
@@ -145,7 +144,7 @@ def test_save_on_exit_cancel_yn():
         h.await_text('cancelled')
 
 
-def test_save_on_exit_cancel_filename():
+def test_save_on_exit_cancel_filename(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.await_text('hello')
@@ -157,7 +156,7 @@ def test_save_on_exit_cancel_filename():
         h.await_text('cancelled')
 
 
-def test_save_on_exit_save(tmpdir):
+def test_save_on_exit(run, tmpdir):
     f = tmpdir.join('f')
     with run(str(f)) as h:
         h.press('hello')
@@ -170,7 +169,7 @@ def test_save_on_exit_save(tmpdir):
         h.await_exit()
 
 
-def test_save_on_exit_resize(tmpdir):
+def test_save_on_exit_resize(run, tmpdir):
     with run() as h, and_exit(h):
         h.press('hello')
         h.await_text('hello')

tests/search_test.py

@@ -1,10 +1,9 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_search_wraps(ten_lines):
+def test_search_wraps(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Down')
         h.press('Down')
@@ -16,7 +15,7 @@ def test_search_wraps(ten_lines):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_search_find_next_line(ten_lines):
+def test_search_find_next_line(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.await_cursor_position(x=0, y=1)
         h.press('^W')
@@ -25,7 +24,7 @@ def test_search_find_next_line(ten_lines):
         h.await_cursor_position(x=0, y=2)
 
 
-def test_search_find_later_in_line():
+def test_search_find_later_in_line(run):
     with run() as h, and_exit(h):
         h.press_and_enter('lol')
         h.press('Up')
@@ -38,7 +37,7 @@ def test_search_find_later_in_line():
         h.await_cursor_position(x=2, y=1)
 
 
-def test_search_only_one_match_already_at_that_match(ten_lines):
+def test_search_only_one_match_already_at_that_match(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
@@ -49,7 +48,7 @@ def test_search_only_one_match_already_at_that_match(ten_lines):
         h.await_cursor_position(x=0, y=2)
 
 
-def test_search_sets_x_hint_properly(tmpdir):
+def test_search_sets_x_hint_properly(run, tmpdir):
     f = tmpdir.join('f')
     contents = '''\
 beginning_line
@@ -67,7 +66,7 @@ match me!
         h.await_cursor_position(x=6, y=1)
 
 
-def test_search_not_found(ten_lines):
+def test_search_not_found(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^W')
         h.await_text('search:')
@@ -76,7 +75,7 @@ def test_search_not_found(ten_lines):
         h.await_cursor_position(x=0, y=1)
 
 
-def test_search_invalid_regex(ten_lines):
+def test_search_invalid_regex(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^W')
         h.await_text('search:')
@@ -85,7 +84,7 @@ def test_search_invalid_regex(ten_lines):
 
 
 @pytest.mark.parametrize('key', ('Enter', '^C'))
-def test_search_cancel(ten_lines, key):
+def test_search_cancel(run, ten_lines, key):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^W')
         h.await_text('search:')
@@ -93,7 +92,7 @@ def test_search_cancel(ten_lines, key):
         h.await_text('cancelled')
 
 
-def test_search_repeated_search(ten_lines):
+def test_search_repeated_search(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('^W')
         h.press('line')
@@ -107,7 +106,7 @@ def test_search_repeated_search(ten_lines):
         h.await_cursor_position(x=0, y=3)
 
 
-def test_search_history_recorded():
+def test_search_history_recorded(run):
     with run() as h, and_exit(h):
         h.press('^W')
         h.await_text('search:')
@@ -127,7 +126,7 @@ def test_search_history_recorded():
         h.await_text('asdtest')
         h.press('Up')  # can't go past the beginning
         h.await_text('asdtest')
-        h.press('enter')
+        h.press('Enter')
         h.await_text('no matches')
 
         h.press('^W')
@@ -138,7 +137,7 @@ def test_search_history_recorded():
         h.press('^C')
 
 
-def test_search_history_duplicates_dont_repeat():
+def test_search_history_duplicates_dont_repeat(run):
     with run() as h, and_exit(h):
         h.press('^W')
         h.await_text('search:')
@@ -163,7 +162,7 @@ def test_search_history_duplicates_dont_repeat():
         h.press('Enter')
 
 
-def test_search_history_is_saved_between_sessions(xdg_data_home):
+def test_search_history_is_saved_between_sessions(run, xdg_data_home):
     with run() as h, and_exit(h):
         h.press('^W')
         h.press_and_enter('search1')
@@ -182,7 +181,7 @@ def test_search_history_is_saved_between_sessions(xdg_data_home):
         h.press('Enter')
 
 
-def test_search_multiple_sessions_append_to_history(xdg_data_home):
+def test_search_multiple_sessions_append_to_history(run, xdg_data_home):
     xdg_data_home.join('babi/history/search').ensure().write(
         'orig\n'
         'history\n',
@@ -205,7 +204,7 @@ def test_search_multiple_sessions_append_to_history(xdg_data_home):
 
 
 @pytest.mark.parametrize('key', ('BSpace', '^H'))
-def test_search_reverse_search_history_backspace(xdg_data_home, key):
+def test_search_reverse_search_history_backspace(run, xdg_data_home, key):
     xdg_data_home.join('babi/history/search').ensure().write(
         'line_5\n'
         'line_3\n'
@@ -222,7 +221,7 @@ def test_search_reverse_search_history_backspace(xdg_data_home, key):
         h.press('^C')
 
 
-def test_search_reverse_search_history(xdg_data_home, ten_lines):
+def test_search_reverse_search_history(run, xdg_data_home, ten_lines):
     xdg_data_home.join('babi/history/search').ensure().write(
         'line_5\n'
         'line_3\n'
@@ -240,7 +239,7 @@ def test_search_reverse_search_history(xdg_data_home, ten_lines):
         h.await_cursor_position(x=0, y=4)
 
 
-def test_search_reverse_search_history_pos_after(xdg_data_home, ten_lines):
+def test_search_reverse_search_pos_after(run, xdg_data_home, ten_lines):
     xdg_data_home.join('babi/history/search').ensure().write(
         'line_3\n',
     )
@@ -255,7 +254,7 @@ def test_search_reverse_search_history_pos_after(xdg_data_home, ten_lines):
         h.press('^C')
 
 
-def test_search_reverse_search_enter_saves_entry(xdg_data_home, ten_lines):
+def test_search_reverse_search_enter_appends(run, xdg_data_home, ten_lines):
     xdg_data_home.join('babi/history/search').ensure().write(
         'line_1\n'
         'line_3\n',
@@ -272,7 +271,7 @@ def test_search_reverse_search_enter_saves_entry(xdg_data_home, ten_lines):
         h.press('^C')
 
 
-def test_search_reverse_search_history_cancel():
+def test_search_reverse_search_history_cancel(run):
     with run() as h, and_exit(h):
         h.press('^W')
         h.press('^R')
@@ -281,7 +280,7 @@ def test_search_reverse_search_history_cancel():
         h.await_text('cancelled')
 
 
-def test_search_reverse_search_resizing():
+def test_search_reverse_search_resizing(run):
     with run() as h, and_exit(h):
         h.press('^W')
         h.press('^R')
@@ -290,7 +289,7 @@ def test_search_reverse_search_resizing():
             h.press('^C')
 
 
-def test_search_reverse_search_does_not_wrap_around(xdg_data_home):
+def test_search_reverse_search_does_not_wrap_around(run, xdg_data_home):
     xdg_data_home.join('babi/history/search').ensure().write(
         'line_1\n'
         'line_3\n',
@@ -305,7 +304,7 @@ def test_search_reverse_search_does_not_wrap_around(xdg_data_home):
         h.press('^C')
 
 
-def test_search_reverse_search_ctrl_r_on_failed_match(xdg_data_home):
+def test_search_reverse_search_ctrl_r_on_failed_match(run, xdg_data_home):
     xdg_data_home.join('babi/history/search').ensure().write(
         'nomatch\n'
         'line_1\n',
@@ -320,7 +319,7 @@ def test_search_reverse_search_ctrl_r_on_failed_match(xdg_data_home):
         h.press('^C')
 
 
-def test_search_reverse_search_keeps_current_text_displayed():
+def test_search_reverse_search_keeps_current_text_displayed(run):
     with run() as h, and_exit(h):
         h.press('^W')
         h.press('ohai')
@@ -330,7 +329,7 @@ def test_search_reverse_search_keeps_current_text_displayed():
         h.press('^C')
 
 
-def test_search_history_extra_blank_lines(xdg_data_home):
+def test_search_history_extra_blank_lines(run, xdg_data_home):
     with run() as h, and_exit(h):
         h.press('^W')
         h.press_and_enter('hello')

tests/sort_test.py

@@ -1,7 +1,6 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 from testing.runner import trigger_command_mode
 
 
@@ -12,7 +11,7 @@ def unsorted(tmpdir):
     return f
 
 
-def test_sort_entire_file(unsorted):
+def test_sort_entire_file(run, unsorted):
     with run(str(unsorted)) as h, and_exit(h):
         trigger_command_mode(h)
         h.press_and_enter(':sort')
@@ -22,7 +21,7 @@ def test_sort_entire_file(unsorted):
     assert unsorted.read() == 'a\nb\nc\nd\n'
 
 
-def test_sort_selection(unsorted):
+def test_sort_selection(run, unsorted):
     with run(str(unsorted)) as h, and_exit(h):
         h.press('S-Down')
         trigger_command_mode(h)
@@ -33,7 +32,7 @@ def test_sort_selection(unsorted):
     assert unsorted.read() == 'b\nd\nc\na\n'
 
 
-def test_sort_selection_does_not_include_eof(unsorted):
+def test_sort_selection_does_not_include_eof(run, unsorted):
     with run(str(unsorted)) as h, and_exit(h):
         for _ in range(5):
             h.press('S-Down')

tests/status_test.py

@@ -1,20 +1,19 @@
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_status_clearing_behaviour():
+def test_status_clearing_behaviour(run):
     with run() as h, and_exit(h):
         h.press('^J')
         h.await_text('unknown key')
         for i in range(24):
-            h.press('LEFT')
+            h.press('Left')
         h.await_text('unknown key')
-        h.press('LEFT')
+        h.press('Left')
         h.await_text_missing('unknown key')
 
 
-def test_very_narrow_window_status():
+def test_very_narrow_window_status(run):
     with run(height=50) as h, and_exit(h):
-        with h.resize(5, 50):
+        with h.resize(width=5, height=50):
             h.press('^J')
             h.await_text('unkno')

tests/suspend_test.py

@@ -12,7 +12,7 @@ def test_suspend(tmpdir):
     with PrintsErrorRunner('bash', '--norc') as h:
         cmd = (sys.executable, '-mcoverage', 'run', '-m', 'babi', str(f))
         h.press_and_enter(' '.join(shlex.quote(part) for part in cmd))
-        h.await_text(babi.VERSION_STR)
+        h.await_text(babi.VERSION_STR, timeout=2)
         h.await_text('hello')
 
         h.press('^Z')
@@ -33,7 +33,7 @@ def test_suspend_with_resize(tmpdir):
     with PrintsErrorRunner('bash', '--norc') as h:
         cmd = (sys.executable, '-mcoverage', 'run', '-m', 'babi', str(f))
         h.press_and_enter(' '.join(shlex.quote(part) for part in cmd))
-        h.await_text(babi.VERSION_STR)
+        h.await_text(babi.VERSION_STR, timeout=2)
         h.await_text('hello')
 
         h.press('^Z')

tests/text_editing_test.py

@@ -1,28 +1,27 @@
 import pytest
 
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_basic_text_editing(tmpdir):
+def test_basic_text_editing(run, tmpdir):
     with run() as h, and_exit(h):
         h.press('hello world')
         h.await_text('hello world')
         h.press('Down')
         h.press('bye!')
         h.await_text('bye!')
-        assert h.screenshot().strip().endswith('world\nbye!')
+        h.await_text('hello world\nbye!\n')
 
 
-def test_backspace_at_beginning_of_file():
+def test_backspace_at_beginning_of_file(run):
     with run() as h, and_exit(h):
         h.press('BSpace')
         h.await_text_missing('unknown key')
-        assert h.screenshot().strip().splitlines()[1:] == []
+        h.assert_cursor_line_equals('')
-        assert '*' not in h.screenshot()
+        h.await_text_missing('*')
 
 
-def test_backspace_joins_lines(tmpdir):
+def test_backspace_joins_lines(run, tmpdir):
     f = tmpdir.join('f')
     f.write('foo\nbar\nbaz\n')
 
@@ -38,7 +37,7 @@ def test_backspace_joins_lines(tmpdir):
         h.await_cursor_position(x=3, y=2)
 
 
-def test_backspace_at_end_of_file_still_allows_scrolling_down(tmpdir):
+def test_backspace_at_end_of_file_still_allows_scrolling_down(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello world')
 
@@ -48,11 +47,11 @@ def test_backspace_at_end_of_file_still_allows_scrolling_down(tmpdir):
         h.press('BSpace')
         h.press('Down')
         h.await_cursor_position(x=0, y=2)
-        assert '*' not in h.screenshot()
+        h.await_text_missing('*')
 
 
 @pytest.mark.parametrize('key', ('BSpace', '^H'))
-def test_backspace_deletes_text(tmpdir, key):
+def test_backspace_deletes_text(run, tmpdir, key):
     f = tmpdir.join('f')
     f.write('ohai there')
 
@@ -66,14 +65,14 @@ def test_backspace_deletes_text(tmpdir, key):
         h.await_cursor_position(x=2, y=1)
 
 
-def test_delete_at_end_of_file(tmpdir):
+def test_delete_at_end_of_file(run, tmpdir):
     with run() as h, and_exit(h):
         h.press('DC')
         h.await_text_missing('unknown key')
         h.await_text_missing('*')
 
 
-def test_delete_removes_character_afterwards(tmpdir):
+def test_delete_removes_character_afterwards(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello world')
 
@@ -85,7 +84,7 @@ def test_delete_removes_character_afterwards(tmpdir):
         h.await_text('f *')
 
 
-def test_delete_at_end_of_line(tmpdir):
+def test_delete_at_end_of_line(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello\nworld\n')
 
@@ -98,7 +97,7 @@ def test_delete_at_end_of_line(tmpdir):
         h.await_text('f *')
 
 
-def test_press_enter_beginning_of_file(tmpdir):
+def test_press_enter_beginning_of_file(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello world')
 
@@ -110,7 +109,7 @@ def test_press_enter_beginning_of_file(tmpdir):
         h.await_text('f *')
 
 
-def test_press_enter_mid_line(tmpdir):
+def test_press_enter_mid_line(run, tmpdir):
     f = tmpdir.join('f')
     f.write('hello world')
 

tests/undo_redo_test.py

@@ -1,8 +1,7 @@
 from testing.runner import and_exit
-from testing.runner import run
 
 
-def test_nothing_to_undo_redo():
+def test_nothing_to_undo_redo(run):
     with run() as h, and_exit(h):
         h.press('M-u')
         h.await_text('nothing to undo!')
@@ -10,7 +9,7 @@ def test_nothing_to_undo_redo():
         h.await_text('nothing to redo!')
 
 
-def test_undo_redo():
+def test_undo_redo(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.await_text('hello')
@@ -24,7 +23,7 @@ def test_undo_redo():
         h.await_text(' *')
 
 
-def test_undo_redo_movement_interrupts_actions():
+def test_undo_redo_movement_interrupts_actions(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.press('Left')
@@ -35,7 +34,7 @@ def test_undo_redo_movement_interrupts_actions():
         h.await_text('hello')
 
 
-def test_undo_redo_action_interrupts_actions():
+def test_undo_redo_action_interrupts_actions(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.await_text('hello')
@@ -50,7 +49,7 @@ def test_undo_redo_action_interrupts_actions():
         h.await_text('hello')
 
 
-def test_undo_redo_mixed_newlines(tmpdir):
+def test_undo_redo_mixed_newlines(run, tmpdir):
     f = tmpdir.join('f')
     f.write_binary(b'foo\nbar\r\n')
 
@@ -61,7 +60,7 @@ def test_undo_redo_mixed_newlines(tmpdir):
         h.await_text(' *')
 
 
-def test_undo_redo_with_save(tmpdir):
+def test_undo_redo_with_save(run, tmpdir):
     f = tmpdir.join('f').ensure()
 
     with run(str(f)) as h, and_exit(h):
@@ -80,22 +79,25 @@ def test_undo_redo_with_save(tmpdir):
         h.await_text(' *')
 
 
-def test_undo_redo_implicit_linebreak(tmpdir):
+def test_undo_redo_implicit_linebreak(run, tmpdir):
     f = tmpdir.join('f')
 
+    def _assert_contents(s):
+        assert f.read() == s
+
     with run(str(f)) as h, and_exit(h):
         h.press('hello')
         h.press('M-u')
         h.press('^S')
         h.await_text('saved!')
-        assert f.read() == ''
+        h.run(lambda: _assert_contents(''))
         h.press('M-U')
         h.press('^S')
         h.await_text('saved!')
-        assert f.read() == 'hello\n'
+        h.run(lambda: _assert_contents('hello\n'))
 
 
-def test_redo_cleared_after_action(tmpdir):
+def test_redo_cleared_after_action(run, tmpdir):
     with run() as h, and_exit(h):
         h.press('hello')
         h.press('M-u')
@@ -104,7 +106,7 @@ def test_redo_cleared_after_action(tmpdir):
         h.await_text('nothing to redo!')
 
 
-def test_undo_no_action_when_noop():
+def test_undo_no_action_when_noop(run):
     with run() as h, and_exit(h):
         h.press('hello')
         h.press('Enter')
@@ -116,7 +118,7 @@ def test_undo_no_action_when_noop():
         h.await_cursor_position(x=0, y=2)
 
 
-def test_undo_redo_causes_scroll():
+def test_undo_redo_causes_scroll(run):
     with run(height=8) as h, and_exit(h):
         for i in range(10):
             h.press('Enter')