Fix edge cases with very short windows

babi.py

@@ -85,21 +85,35 @@ def _write_header(
     stdscr.addstr(0, 0, s, curses.A_REVERSE)
 
 
-def _write_status(stdscr: '_curses._CursesWindow', status: str) -> None:
-    stdscr.addstr(curses.LINES - 1, 0, ' ' * (curses.COLS - 1))
-    if status:
-        status = f' {status} '
-        offset = (curses.COLS - len(status)) // 2
-        stdscr.addstr(curses.LINES - 1, offset, status, curses.A_REVERSE)
-
-
 def _write_lines(stdscr: '_curses._CursesWindow', lines: List[str]) -> None:
-    lines_to_display = min(len(lines), curses.LINES - 2)
+    if curses.LINES == 1:
+        header, footer = 0, 0
+    elif curses.LINES == 2:
+        header, footer = 0, 1
+    else:
+        header, footer = 1, 1
+
+    max_lines = curses.LINES - header - footer
+    lines_to_display = min(len(lines), max_lines)
     for i in range(lines_to_display):
-        stdscr.addstr(i + 1, 0, lines[i][:curses.COLS])
+        line = lines[i][:curses.COLS].rstrip('\r\n').ljust(curses.COLS)
+        stdscr.insstr(i + header, 0, line)
     blankline = ' ' * curses.COLS
-    for i in range(lines_to_display, curses.LINES - 2):
+    for i in range(lines_to_display, max_lines):
-        stdscr.addstr(i + 1, 0, blankline)
+        stdscr.insstr(i + header, 0, blankline)
+
+
+def _write_status(stdscr: '_curses._CursesWindow', status: str) -> None:
+    if curses.LINES > 1 or status:
+        stdscr.insstr(curses.LINES - 1, 0, ' ' * curses.COLS)
+        if status:
+            status = f' {status} '
+            offset = (curses.COLS - len(status)) // 2
+            stdscr.addstr(curses.LINES - 1, offset, status, curses.A_REVERSE)
+
+
+def _move(stdscr: '_curses._CursesWindow', x: int, y: int) -> None:
+    stdscr.move(y + (curses.LINES > 2), x)
 
 
 def c_main(stdscr: '_curses._CursesWindow', args: argparse.Namespace) -> None:
@@ -122,17 +136,22 @@ def c_main(stdscr: '_curses._CursesWindow', args: argparse.Namespace) -> None:
     def _set_status(s: str) -> None:
         nonlocal status, status_action_counter
         status = s
-        status_action_counter = 25
+        # if the window is only 1-tall, clear status quicker
+        if curses.LINES == 1:
+            status_action_counter = 1
+        else:
+            status_action_counter = 25
 
     while True:
         if status_action_counter == 0:
             status = ''
         status_action_counter -= 1
 
-        _write_header(stdscr, filename, modified=False)
+        if curses.LINES > 2:
-        _write_status(stdscr, status)
+            _write_header(stdscr, filename, modified=False)
         _write_lines(stdscr, lines)
-        stdscr.move(position_y + 1, position_x)
+        _write_status(stdscr, status)
+        _move(stdscr, x=position_x, y=position_y)
 
         wch = stdscr.get_wch()
         key = wch if isinstance(wch, int) else ord(wch)

tests/babi_test.py

@@ -33,21 +33,20 @@ def run(*args, color=True, **kwargs):
 
 @contextlib.contextmanager
 def and_exit(h):
-    try:
+    yield
-        yield
+    # only try and exit in non-exceptional cases
-    finally:
+    h.press('C-x')
-        h.press('C-x')
+    h.await_exit()
-        h.await_exit()
 
 
-def await_text_missing(h, text):
+def await_text_missing(h, s):
     """largely based on await_text"""
     for _ in h.poll_until_timeout():
         screen = h.screenshot()
         munged = screen.replace('\n', '')
-        if text not in munged:  # pragma: no branch
+        if s not in munged:  # pragma: no branch
             return
-    raise AssertionError(f'Timeout while waiting for text {text!r} to appear')
+    raise AssertionError(f'Timeout while waiting for text {s!r} to disappear')
 
 
 def get_size(h):
@@ -63,7 +62,7 @@ def resize(h, width, height):
     panes = 0
 
     hsplit_w = current_w - width - 1
-    if hsplit_w > 0:  # pragma: no branch  # TODO
+    if hsplit_w > 0:
         cmd = ('split-window', '-ht0', '-l', hsplit_w, 'sleep', 'infinity')
         h.tmux.execute_command(*cmd)
         panes += 1
@@ -108,6 +107,43 @@ def test_window_bounds(tmpdir):
             h.press('DOWN')
 
 
+def test_window_height_2(tmpdir):
+    # 2 tall:
+    # - header is hidden, otherwise behaviour is normal
+    f = tmpdir.join('f.txt')
+    f.write('hello world')
+
+    with run(str(f)) as h, and_exit(h):
+        h.await_text('hello world')
+
+        with resize(h, 80, 2):
+            await_text_missing(h, babi.VERSION_STR)
+            assert h.screenshot() == 'hello world\n\n'
+            h.press('C-j')
+            h.await_text('unknown key')
+
+        h.await_text(babi.VERSION_STR)
+
+
+def test_window_height_1(tmpdir):
+    # 1 tall:
+    # - only file contents as body
+    # - status takes precedence over body, but cleared after single action
+    f = tmpdir.join('f.txt')
+    f.write('hello world')
+
+    with run(str(f)) as h, and_exit(h):
+        h.await_text('hello world')
+
+        with resize(h, 80, 1):
+            await_text_missing(h, babi.VERSION_STR)
+            assert h.screenshot() == 'hello world\n'
+            h.press('C-j')
+            h.await_text('unknown key')
+            h.press('Right')
+            await_text_missing(h, 'unknown key')
+
+
 def test_status_clearing_behaviour():
     with run() as h, and_exit(h):
         h.press('C-j')