Add a test suite and some basic navigation

tests/babi_test.py

@@ -0,0 +1,53 @@
+import contextlib
+import sys
+
+from hecate import Runner
+
+import babi
+
+
+@contextlib.contextmanager
+def run(*args, **kwargs):
+    cmd = (sys.executable, '-mcoverage', 'run', '-m', 'babi', *args)
+    with Runner(*cmd, **kwargs) as h:
+        h.await_text(babi.VERSION_STR)
+        yield h
+
+
+def await_text_missing(h, text):
+    """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
+            return
+    raise AssertionError(f'Timeout while waiting for text {text!r} to appear')
+
+
+def test_window_bounds(tmpdir):
+    f = tmpdir.join('f.txt')
+    f.write(f'{"x" * 40}\n' * 40)
+
+    with run(str(f), width=30, height=30) as h:
+        # make sure we don't go off the top left of the screen
+        h.press('LEFT')
+        h.press('UP')
+        # make sure we don't go off the bottom of the screen
+        for i in range(32):
+            h.press('RIGHT')
+            h.press('DOWN')
+        h.press('C-x')
+        h.await_exit()
+
+
+def test_status_clearing_behaviour():
+    with run() as h:
+        h.press('C-j')
+        h.await_text('unknown key')
+        for i in range(24):
+            h.press('LEFT')
+        h.await_text('unknown key')
+        h.press('LEFT')
+        await_text_missing(h, 'unknown key')
+        h.press('C-x')
+        h.await_exit()