feat: cycle command completions with Tab

tests/unit/editor.rs

@@ -1067,6 +1067,121 @@ fn focused_text_fields_keep_printable_normal_bindings_as_text() {
     }
 }
 
+#[test]
+fn command_completion_cycles_core_alias_and_live_plugin_names_without_executing() {
+    let mut editor = editor();
+    editor.register(plugin("fixture", &["save_note"])).unwrap();
+    let document = editor.context().text;
+    type_text(&mut editor, ":sav");
+    for expected in ["save", "save_and_quit", "save_note", "save"] {
+        assert_eq!(editor.handle(Input::Char('\t')), None);
+        assert_eq!(editor.command_line(), expected);
+        assert_eq!(editor.mode(), Mode::Command);
+        assert_eq!(editor.context().text, document);
+        assert!(!editor.should_quit());
+    }
+    editor.handle(Input::Char('\t'));
+    editor.handle(Input::Char('\t'));
+    let invocation = editor.handle(Input::Enter).unwrap();
+    assert_eq!(invocation.plugin, "fixture");
+    assert_eq!(invocation.command, "save_note");
+    assert_eq!(invocation.args, "");
+
+    type_text(&mut editor, ":q");
+    for expected in ["q", "q!", "quit", "q"] {
+        editor.handle(Input::Char('\t'));
+        assert_eq!(editor.command_line(), expected);
+        assert!(!editor.should_quit());
+    }
+    editor.handle(Input::Escape);
+    type_text(&mut editor, ":sav");
+    editor.handle(Input::Char('\t'));
+    editor.disable_plugin("fixture", "test");
+    for expected in ["save_and_quit", "save"] {
+        editor.handle(Input::Char('\t'));
+        assert_eq!(editor.command_line(), expected);
+    }
+}
+
+#[test]
+fn command_completion_restarts_after_edits_history_and_cancellation_and_ignores_arguments() {
+    let mut editor = editor();
+    type_text(&mut editor, ":plugins\n:sav");
+    editor.handle(Input::Char('\t'));
+    type_text(&mut editor, "_");
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "save_and_quit");
+    editor.handle(Input::Ctrl('u'));
+    type_text(&mut editor, "q!");
+    editor.handle(Input::Backspace);
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "q");
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "q!");
+    editor.handle(Input::Up);
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "plugins");
+    editor.handle(Input::Down);
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "q!");
+    editor.handle(Input::Escape);
+
+    for (draft, expected) in [
+        ("", "bdelete"),
+        ("  :sav", "  :save"),
+        ("no_such_command", "no_such_command"),
+        ("界e\u{301}", "界e\u{301}"),
+        ("edit ", "edit "),
+        ("save 界 file.txt", "save 界 file.txt"),
+    ] {
+        type_text(&mut editor, ":");
+        type_text(&mut editor, draft);
+        editor.handle(Input::Char('\t'));
+        assert_eq!(editor.command_line(), expected);
+        editor.handle(Input::Escape);
+    }
+}
+
+#[test]
+fn command_completion_respects_bindings_and_preserves_visual_diff_and_search_input() {
+    let directory = Directory::new();
+    let mut editor = editor();
+    editor
+        .bind("command", "ctrl+n", Some("core.command_complete".into()))
+        .unwrap();
+    editor.bind("command", "tab", None).unwrap();
+    historical_diff(
+        &mut editor,
+        &directory.0,
+        vec!["needle before".into()],
+        vec!["needle after".into()],
+    );
+    editor.handle(Input::Char('V'));
+    let selections = editor.selections();
+    let cursor = editor.cursor();
+    type_text(&mut editor, ":diff.com");
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "diff.com");
+    editor.handle(Input::Ctrl('n'));
+    assert_eq!(editor.command_line(), "diff.comment");
+    assert_eq!(editor.selections(), selections);
+    assert_eq!(editor.cursor(), cursor);
+    editor.handle(Input::Escape);
+    assert_eq!(editor.mode(), Mode::Visual);
+    assert_eq!(editor.selections(), selections);
+    editor.handle(Input::Escape);
+    type_text(&mut editor, "/sav");
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "sav\t");
+    editor.handle(Input::Escape);
+    editor
+        .bind("command", "tab", Some("core.up".into()))
+        .unwrap();
+    type_text(&mut editor, ":plugins\n:sav");
+    editor.handle(Input::Char('\t'));
+    assert_eq!(editor.command_line(), "plugins");
+}
+
 #[test]
 fn prompt_history_browses_without_executing_and_restores_unicode_drafts() {
     for prefix in [':', '/'] {