command mode (can now be quit with :q)

Co-authored-by: Hayden Young <hayden@haydennyyy.com>

tests/babi_test.py

@@ -183,6 +183,17 @@ def and_exit(h):
     h.await_exit()
 
 
+def trigger_command_mode(h):
+    # in order to enter a steady state, trigger an unknown key first and then
+    # press escape to open the command mode.  this is necessary as `Escape` is
+    # the start of "escape sequences" and sending characters too quickly will
+    # be interpreted as a single keypress
+    h.press('^J')
+    h.await_text('unknown key')
+    h.press('Escape')
+    h.await_text_missing('unknown key')
+
+
 @pytest.mark.parametrize('color', (True, False))
 def test_color_test(color):
     with run('--color-test', color=color) as h, and_exit(h):
@@ -243,13 +254,6 @@ def test_status_clearing_behaviour():
         h.await_text_missing('unknown key')
 
 
-def test_escape_key_behaviour():
-    # TODO: eventually escape will have a command utility, for now: unknown
-    with run() as h, and_exit(h):
-        h.press('Escape')
-        h.await_text('unknown key')
-
-
 def test_reacts_to_resize():
     with run() as h, and_exit(h):
         first_line = h.get_screen_line(0)
@@ -865,3 +869,83 @@ def test_save_file_when_it_did_not_exist(tmpdir):
         h.await_text_missing('*')
 
     assert f.read() == 'hello world\n'
+
+
+def test_quit_via_colon_q():
+    with run() as h:
+        trigger_command_mode(h)
+        h.press_and_enter(':q')
+        h.await_exit()
+
+
+def test_key_navigation_in_command_mode():
+    with run() as h, and_exit(h):
+        trigger_command_mode(h)
+        h.press('hello world')
+        h.await_cursor_position(x=11, y=23)
+        h.press('Left')
+        h.await_cursor_position(x=10, y=23)
+        h.press('Right')
+        h.await_cursor_position(x=11, y=23)
+        h.press('Home')
+        h.await_cursor_position(x=0, y=23)
+        h.press('End')
+        h.await_cursor_position(x=11, y=23)
+        h.press('^A')
+        h.await_cursor_position(x=0, y=23)
+        h.press('^E')
+        h.await_cursor_position(x=11, y=23)
+
+        h.press('DC')  # does nothing at end
+        h.await_cursor_position(x=11, y=23)
+        h.await_text('\nhello world\n')
+
+        h.press('Bspace')
+        h.await_cursor_position(x=10, y=23)
+        h.await_text('\nhello worl\n')
+
+        h.press('Home')
+
+        h.press('Bspace')  # does nothing at beginning
+        h.await_cursor_position(x=0, y=23)
+        h.await_text('\nhello worl\n')
+
+        h.press('DC')
+        h.await_cursor_position(x=0, y=23)
+        h.await_text('\nello worl\n')
+
+        # unknown keys don't do anything
+        h.press('^J')
+        h.await_text('\nello worl\n')
+
+        h.press('Enter')
+
+
+def test_save_via_command_mode(tmpdir):
+    f = tmpdir.join('f')
+
+    with run(str(f)) as h, and_exit(h):
+        h.press('hello world')
+        trigger_command_mode(h)
+        h.press_and_enter(':w')
+
+    assert f.read() == 'hello world\n'
+
+
+def test_resizing_and_scrolling_in_command_mode():
+    with run(width=20) as h, and_exit(h):
+        h.press('a' * 15)
+        h.await_text(f'\n{"a" * 15}\n')
+        trigger_command_mode(h)
+        h.press('b' * 15)
+        h.await_text(f'\n{"b" * 15}\n')
+
+        with h.resize(width=16, height=24):
+            h.await_text('\n«aaaaaa\n')  # the text contents
+            h.await_text('\n«bbbbbb\n')  # the text contents
+            h.await_cursor_position(x=7, y=23)
+            h.press('Left')
+            h.await_cursor_position(x=14, y=23)
+            h.await_text(f'\n{"b" * 15}\n')
+
+        h.press('Enter')