hjkl 0.25.0

use super::*;

// ── App::new tests ──────────────────────────────────────────────────────

#[test]
fn app_new_no_file() {
    let app = App::new(None, false, None, None).unwrap();
    assert!(!app.active().dirty);
    assert!(!app.active().is_new_file);
    assert!(app.active().filename.is_none());
    assert!(!app.active().editor.is_readonly());
}

#[test]
fn app_new_readonly_flag() {
    let app = App::new(None, true, None, None).unwrap();
    assert!(app.active().editor.is_readonly());
}

#[test]
fn app_new_not_found_sets_is_new_file() {
    let path = tmp_path("hjkl_phase5_nonexistent_abc123.txt");
    let _ = std::fs::remove_file(&path);
    let app = App::new(Some(path), false, None, None).unwrap();
    assert!(app.active().is_new_file);
    assert!(!app.active().dirty);
}

#[test]
fn app_new_goto_line_clamps() {
    let app = App::new(None, false, Some(999), None).unwrap();
    let (row, _col) = app.active().editor.cursor();
    assert_eq!(row, 0);
}

#[test]
fn ex_goto_line_100_via_dispatch() {
    let mut app = App::new(None, false, None, None).unwrap();
    // Seed buffer with 120 lines.
    let buf: String = (1..=120)
        .map(|n| format!("line{n}"))
        .collect::<Vec<_>>()
        .join("\n");
    use hjkl_buffer::{Edit, Position};
    app.active_mut().editor.mutate_edit(Edit::InsertStr {
        at: Position::new(0, 0),
        text: buf,
    });
    app.active_mut().editor.jump_cursor(0, 0);
    app.dispatch_ex("100");
    let (row, _col) = app.active().editor.cursor();
    assert_eq!(row, 99, "':100' must land on row 99");
}

#[test]
fn dot_repeat_replays_last_change() {
    use crate::keymap_actions::AppAction;
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
    use hjkl_buffer::{Edit, Position};
    let mut app = App::new(None, false, None, None).unwrap();
    app.active_mut().editor.mutate_edit(Edit::InsertStr {
        at: Position::new(0, 0),
        text: "abc".to_string(),
    });
    app.active_mut().editor.jump_cursor(0, 0);
    // Set up a last_change by feeding `x` through the engine (single-char delete).
    hjkl_vim::handle_key(
        &mut app.active_mut().editor,
        KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE),
    );
    // Buffer now "bc". Dot-repeat should delete one more char.
    app.dispatch_action(AppAction::DotRepeat { count: 1 }, 1);
    let line0 = app.active().editor.buffer().line(0).map(|l| l.to_string());
    assert_eq!(
        line0.as_deref(),
        Some("c"),
        "`.` after `x` must delete one more char, got {line0:?}"
    );
}

#[test]
fn dot_repeat_with_count_3_replays_three_times() {
    use crate::keymap_actions::AppAction;
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
    use hjkl_buffer::{Edit, Position};
    let mut app = App::new(None, false, None, None).unwrap();
    app.active_mut().editor.mutate_edit(Edit::InsertStr {
        at: Position::new(0, 0),
        text: "abcdef".to_string(),
    });
    app.active_mut().editor.jump_cursor(0, 0);
    hjkl_vim::handle_key(
        &mut app.active_mut().editor,
        KeyEvent::new(KeyCode::Char('x'), KeyModifiers::NONE),
    );
    // Buffer "bcdef". `3.` deletes 3 more. Seed pending_count to simulate
    // the keymap layer's count-prefix accumulation.
    app.pending_count.try_accumulate('3');
    app.dispatch_action(AppAction::DotRepeat { count: 1 }, 1);
    let line0 = app.active().editor.buffer().line(0).map(|l| l.to_string());
    assert_eq!(
        line0.as_deref(),
        Some("ef"),
        "`3.` after `x` must delete 3 more chars, got {line0:?}"
    );
}

#[test]
fn ex_goto_line_100_via_command_field_keys() {
    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
    use hjkl_buffer::{Edit, Position};
    let mut app = App::new(None, false, None, None).unwrap();
    let buf: String = (1..=120)
        .map(|n| format!("line{n}"))
        .collect::<Vec<_>>()
        .join("\n");
    app.active_mut().editor.mutate_edit(Edit::InsertStr {
        at: Position::new(0, 0),
        text: buf,
    });
    app.active_mut().editor.jump_cursor(0, 0);
    // Open command prompt, type "100", press Enter — simulate full user path.
    app.open_command_prompt();
    for c in ['1', '0', '0'] {
        app.handle_command_field_key(KeyEvent::new(KeyCode::Char(c), KeyModifiers::NONE));
    }
    app.handle_command_field_key(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
    let (row, _col) = app.active().editor.cursor();
    assert_eq!(
        row, 99,
        "':100<Enter>' via command-field must land on row 99, got {row}"
    );
    // Critical: the window cursor cache (used at render time) must also
    // reflect the move. Without sync_viewport_from_editor after ex::run,
    // engine cursor moves but render shows stale position.
    let fw = app.focused_window();
    let win = app.windows[fw].as_ref().unwrap();
    assert_eq!(
        win.cursor_row, 99,
        "window cache cursor_row must follow engine cursor after `:100`"
    );
}

#[test]
fn do_save_readonly_blocked() {
    let mut app = App::new(None, true, None, None).unwrap();
    app.active_mut().filename = Some(tmp_path("hjkl_phase5_ro_test.txt"));
    app.do_save(None);
    let msg = app.bus.last_body_or_empty().to_string();
    assert!(
        msg.contains("E45"),
        "expected E45 readonly error, got: {msg}"
    );
}

#[test]
fn do_save_no_filename_e32() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.do_save(None);
    let msg = app.bus.last_body_or_empty().to_string();
    assert!(msg.contains("E32"), "expected E32, got: {msg}");
}

// ── Start screen tests ─────────────────────────────────────────────────

#[test]
fn start_screen_present_when_no_file() {
    let app = App::new(None, false, None, None).unwrap();
    assert!(
        app.start_screen.is_some(),
        "start_screen must be Some when no file given"
    );
}

#[test]
fn start_screen_absent_when_file_given() {
    let path = std::env::temp_dir().join("hjkl_splash_with_file.txt");
    std::fs::write(&path, "x\n").unwrap();
    let app = App::new(Some(path.clone()), false, None, None).unwrap();
    assert!(
        app.start_screen.is_none(),
        "start_screen must be None when file given"
    );
    let _ = std::fs::remove_file(&path);
}

#[test]
fn mode_label_returns_start_during_splash() {
    let app = App::new(None, false, None, None).unwrap();
    assert!(app.start_screen.is_some());
    assert_eq!(app.mode_label(), "START");
}

// Splash tick advancement is now wall-clock driven inside `hjkl-splash`
// (see its own unit tests); apps/hjkl just constructs the splash and
// renders it. No tick assertions live here.

// ── Config layering tests ──────────────────────────────────────────────

#[test]
fn with_config_updates_leader_and_reapplies_to_existing_slot() {
    // Smoke test for the slot-0 boot-order fix: App::new builds slot 0
    // before any user config is wired, so with_config must propagate the
    // new config and re-apply Options to existing slots. This test pins
    // the public observable: app.config reflects the override, and the
    // re-application path does not panic with a single-slot app.
    let app = App::new(None, false, None, None).unwrap();
    assert_eq!(app.config.editor.leader, ' ');

    let mut cfg = hjkl_app::config::Config::default();
    cfg.editor.leader = '\\';
    cfg.editor.tab_width = 2;
    let app = app.with_config(cfg);

    assert_eq!(app.config.editor.leader, '\\');
    assert_eq!(app.config.editor.tab_width, 2);
    assert_eq!(
        app.slots.len(),
        1,
        "with_config should not add or drop slots"
    );
}

#[test]
fn with_config_preserves_readonly_on_existing_slot() {
    // Slots opened with readonly = true must stay readonly after a
    // user-config swap (the re-applied Options must not silently flip
    // the bit back to false).
    let app = App::new(None, true, None, None).unwrap();
    assert!(app.active().editor.is_readonly());

    let app = app.with_config(hjkl_app::config::Config::default());
    assert!(
        app.active().editor.is_readonly(),
        "readonly state must survive with_config re-application"
    );
}

#[test]
fn config_load_from_disk_then_with_config_propagates_overrides() {
    // End-to-end pipeline: write a user config to a tempfile, parse it
    // through the on-disk loader (deep-merged over bundled defaults),
    // hand the result to App::with_config, and verify the override
    // landed on the App. Pins the `--config <PATH>` path that main
    // uses without spinning up the terminal.
    use std::io::Write as _;
    let mut tmp = tempfile::NamedTempFile::new().unwrap();
    writeln!(
        tmp,
        r#"
        [editor]
        leader = "\\"
        tab_width = 2

        [theme]
        name = "dark"
        "#
    )
    .unwrap();

    let cfg = hjkl_app::config::load_from(tmp.path()).expect("load_from must succeed");
    // Bundled defaults survived for fields the user file omitted:
    assert_eq!(cfg.editor.huge_file_threshold, 50_000);
    assert!(cfg.editor.expandtab);
    // User overrides won where present:
    assert_eq!(cfg.editor.leader, '\\');
    assert_eq!(cfg.editor.tab_width, 2);

    use hjkl_config::Validate;
    cfg.validate()
        .expect("merged user+default config must validate");

    let app = App::new(None, false, None, None).unwrap().with_config(cfg);
    assert_eq!(app.config.editor.leader, '\\');
    assert_eq!(app.config.editor.tab_width, 2);
}

#[test]
fn config_load_from_disk_validation_failure_surfaces() {
    // Out-of-range values parse cleanly but the Validate impl rejects
    // them. The pipeline must surface the field name so users can
    // identify the offending key.
    use std::io::Write as _;
    let mut tmp = tempfile::NamedTempFile::new().unwrap();
    writeln!(tmp, "[editor]\nhuge_file_threshold = 0").unwrap();

    let cfg = hjkl_app::config::load_from(tmp.path()).expect("parse must succeed");

    use hjkl_config::Validate;
    let err = cfg.validate().unwrap_err();
    assert_eq!(err.field, "editor.huge_file_threshold");
}

// ── Render-level :set option tests ──────────────────────────────────────────

#[test]
fn set_cursorline_flips_setting() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(
        app.active().editor.settings().cursorline,
        "cursorline must default to true"
    );
    app.dispatch_ex("set nocursorline");
    assert!(
        !app.active().editor.settings().cursorline,
        ":set nocursorline must disable cursorline"
    );
    app.dispatch_ex("set cursorline");
    assert!(
        app.active().editor.settings().cursorline,
        ":set cursorline must enable cursorline"
    );
}

#[test]
fn set_cul_alias_works() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_ex("set cul");
    assert!(
        app.active().editor.settings().cursorline,
        ":set cul must enable cursorline"
    );
}

#[test]
fn set_cursorcolumn_flips_setting() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(!app.active().editor.settings().cursorcolumn);
    app.dispatch_ex("set cuc");
    assert!(app.active().editor.settings().cursorcolumn);
    app.dispatch_ex("set nocuc");
    assert!(!app.active().editor.settings().cursorcolumn);
}

#[test]
fn set_signcolumn_yes() {
    use hjkl_engine::types::SignColumnMode;
    let mut app = App::new(None, false, None, None).unwrap();
    assert_eq!(
        app.active().editor.settings().signcolumn,
        SignColumnMode::Auto,
        "signcolumn defaults to auto"
    );
    app.dispatch_ex("set signcolumn=yes");
    assert_eq!(
        app.active().editor.settings().signcolumn,
        SignColumnMode::Yes
    );
}

#[test]
fn set_signcolumn_scl_alias() {
    use hjkl_engine::types::SignColumnMode;
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_ex("set scl=no");
    assert_eq!(
        app.active().editor.settings().signcolumn,
        SignColumnMode::No
    );
}

#[test]
fn set_foldcolumn_stores_value() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert_eq!(app.active().editor.settings().foldcolumn, 0);
    app.dispatch_ex("set foldcolumn=4");
    assert_eq!(app.active().editor.settings().foldcolumn, 4);
    app.dispatch_ex("set fdc=0");
    assert_eq!(app.active().editor.settings().foldcolumn, 0);
}

#[test]
fn set_colorcolumn_stores_value() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert_eq!(app.active().editor.settings().colorcolumn, "");
    app.dispatch_ex("set cc=80");
    assert_eq!(app.active().editor.settings().colorcolumn, "80");
    app.dispatch_ex("set colorcolumn=80,120");
    assert_eq!(app.active().editor.settings().colorcolumn, "80,120");
    app.dispatch_ex("set cc=");
    assert_eq!(app.active().editor.settings().colorcolumn, "");
}

// ── issue #120 Phase 2 regression tests ─────────────────────────────────────
//
// These tests verify that `:`, `/`, `?`, `K`, and `<C-^>` are dispatched
// through the keymap trie (route_chord_key) rather than inline intercepts.
//
// Critical regression: `<leader>/` must open the grep picker, NOT the
// search prompt. The `leader_slash_no_inline_intercept_regression` test
// would fail if a bare `/` intercept fired before the trie consumed the
// second key of the `<leader>/` chord.
//
// How to verify the test gates the old bug: temporarily add an inline
// `/` intercept in event_loop.rs that fires BEFORE route_chord_key —
// the test will fail because the search prompt opens instead of the picker.

/// `<leader>/` opens the grep picker, not the search prompt.
///
/// This is the canonical regression for 1ed6e7b: an inline `/` intercept
/// that fires before the keymap trie is consumed would swallow the `/` and
/// open the search prompt instead of completing the `<leader>/` chord.
/// Because there is no longer an inline intercept, the trie handles `/`
/// entirely and this test catches any regression that re-introduces one.
#[test]
fn leader_slash_no_inline_intercept_regression() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.picker.is_none(), "picker must start None");
    assert!(app.search_field.is_none(), "search_field must start None");

    // Feed <leader> (Space) + `/` through route_chord_key.
    // The keymap trie has `<leader>/` → OpenGrepPicker and bare `/` →
    // OpenSearchPrompt(Forward). The trie must resolve to the longer chord.
    app.route_chord_key(key(KeyCode::Char(' ')));
    app.route_chord_key(key(KeyCode::Char('/')));

    assert!(
        app.picker.is_some(),
        "<leader>/ must open the grep picker, not the search prompt"
    );
    assert!(
        app.search_field.is_none(),
        "<leader>/ must NOT open the search prompt"
    );
}

/// Bare `:` opens the command prompt via the keymap trie.
#[test]
fn colon_opens_command_prompt_via_keymap() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.command_field.is_none());
    app.route_chord_key(key(KeyCode::Char(':')));
    assert!(
        app.command_field.is_some(),
        "`:` must open the command prompt via keymap dispatch"
    );
}

/// Bare `/` opens the forward search prompt via the keymap trie.
#[test]
fn slash_opens_search_prompt_forward_via_keymap() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.search_field.is_none());
    app.route_chord_key(key(KeyCode::Char('/')));
    assert!(
        app.search_field.is_some(),
        "`/` must open the search prompt via keymap dispatch"
    );
}

/// Bare `?` opens the backward search prompt via the keymap trie.
#[test]
fn question_opens_search_prompt_backward_via_keymap() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.search_field.is_none());
    app.route_chord_key(key(KeyCode::Char('?')));
    assert!(
        app.search_field.is_some(),
        "`?` must open the search prompt via keymap dispatch"
    );
}

/// `<C-^>` triggers buffer alt via the keymap trie.
/// With a single slot it's a no-op (status message), not an error.
#[test]
fn ctrl_caret_triggers_buffer_alt_via_keymap() {
    let mut app = App::new(None, false, None, None).unwrap();
    // Single slot: buffer_alt sets a status message; no panic.
    app.route_chord_key(ctrl_key('^'));
    // Just assert we didn't panic and the app is still alive.
    assert!(app.picker.is_none(), "ctrl-^ must not open picker");
}

// ── issue #120 Phase 3 regression tests ─────────────────────────────────────

/// `H` with a single slot falls back to viewport-top motion (no buffer cycle).
#[test]
fn h_single_slot_fallback_to_viewport_top() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert_eq!(app.slots.len(), 1, "test requires single slot");
    // H should not crash and should be consumed by the keymap.
    let consumed = app.route_chord_key(key(KeyCode::Char('H')));
    assert!(consumed, "H must be consumed by keymap (BufferCycleH)");
}

/// `L` with a single slot falls back to viewport-bottom motion.
#[test]
fn l_single_slot_fallback_to_viewport_bottom() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert_eq!(app.slots.len(), 1, "test requires single slot");
    let consumed = app.route_chord_key(key(KeyCode::Char('L')));
    assert!(consumed, "L must be consumed by keymap (BufferCycleL)");
}

/// `<C-h>` on a single-window layout triggers tmux path (no-op without TMUX).
#[test]
fn ctrl_h_single_window_no_tmux_no_panic() {
    let mut app = App::new(None, false, None, None).unwrap();
    // TMUX not set: TmuxNavigate falls through to no-op.
    // Must not panic and must consume the key.
    let consumed = app.route_chord_key(ctrl_key('h'));
    assert!(consumed, "<C-h> must be consumed by keymap (TmuxNavigate)");
}

// ── issue #120 Phase 4 regression tests ─────────────────────────────────────
// These tests call handle_keypress directly (the extracted method) to verify
// the full key dispatch path including overlay and prefix handling.

/// `handle_keypress` returns Break on Ctrl-C with no overlay active.
#[test]
fn handle_keypress_ctrl_c_breaks() {
    use crate::app::event_loop::KeyOutcome;
    let mut app = App::new(None, false, None, None).unwrap();
    let outcome = app.handle_keypress(ctrl_key('c'));
    assert!(
        matches!(outcome, KeyOutcome::Break),
        "Ctrl-C with no overlay must return Break"
    );
}

/// `handle_keypress` returns Continue (dismisses command field) on Ctrl-C with command field open.
#[test]
fn handle_keypress_ctrl_c_dismisses_command_field() {
    use crate::app::event_loop::KeyOutcome;
    let mut app = App::new(None, false, None, None).unwrap();
    app.open_command_prompt();
    assert!(app.command_field.is_some());
    let outcome = app.handle_keypress(ctrl_key('c'));
    assert!(
        matches!(outcome, KeyOutcome::Continue),
        "Ctrl-C with command field open must dismiss and return Continue"
    );
    assert!(app.command_field.is_none());
}

/// `handle_keypress` routes `:` to the command prompt (via keymap trie).
#[test]
fn handle_keypress_colon_opens_command_prompt() {
    use crate::app::event_loop::KeyOutcome;
    let mut app = App::new(None, false, None, None).unwrap();
    let outcome = app.handle_keypress(key(KeyCode::Char(':')));
    assert!(
        matches!(outcome, KeyOutcome::Continue),
        "`:` must return Continue after opening command prompt"
    );
    assert!(
        app.command_field.is_some(),
        "`:` must open the command prompt"
    );
}

/// `<leader>/` via handle_keypress opens the grep picker, not the search prompt.
///
/// This is the Phase 4 variant of `leader_slash_no_inline_intercept_regression`:
/// it exercises the full handle_keypress path rather than the inner route_chord_key.
#[test]
fn handle_keypress_leader_slash_opens_grep_picker() {
    use crate::app::event_loop::KeyOutcome;
    let mut app = App::new(None, false, None, None).unwrap();
    // Feed <leader> (Space) — returns Continue (chord in flight).
    let o1 = app.handle_keypress(key(KeyCode::Char(' ')));
    assert!(
        matches!(o1, KeyOutcome::Continue),
        "<leader> first key must return Continue"
    );
    // Feed `/` — trie resolves to OpenGrepPicker.
    let o2 = app.handle_keypress(key(KeyCode::Char('/')));
    assert!(
        matches!(o2, KeyOutcome::Continue),
        "<leader>/ second key must return Continue"
    );
    assert!(
        app.picker.is_some(),
        "<leader>/ via handle_keypress must open grep picker"
    );
    assert!(
        app.search_field.is_none(),
        "<leader>/ via handle_keypress must NOT open search prompt"
    );
}

// ── Sub-dispatcher canary tests (issue #121) ─────────────────────────────────

#[test]
fn dispatch_picker_action_opens_file_picker() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.picker.is_none(), "picker starts closed");
    app.dispatch_action(AppAction::OpenFilePicker, 1);
    assert!(app.picker.is_some(), "OpenFilePicker must open picker");
}

#[test]
fn dispatch_picker_action_opens_buffer_picker() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::OpenBufferPicker, 1);
    assert!(app.picker.is_some(), "OpenBufferPicker must open picker");
}

#[test]
fn dispatch_git_action_status_sets_picker_or_notification() {
    // Without a git repo the picker may or may not open (implementation
    // detail), but the call must not panic.
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::GitStatus, 1);
    // Either a picker opened or a status message was set — both are valid.
    let reacted = app.picker.is_some() || app.bus.last_body().is_some();
    assert!(reacted, "GitStatus must open picker or set status message");
}

#[test]
fn dispatch_lsp_action_lsp_rename_sets_notification() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::LspRename, 1);
    assert!(
        app.bus.last_body().is_some(),
        "LspRename must push a notification"
    );
    let msg = app.bus.last_body_or_empty();
    assert!(
        msg.contains("Rename"),
        "LspRename status must mention :Rename, got: {msg}"
    );
}

#[test]
fn dispatch_window_action_focus_left_on_single_window_no_panic() {
    // Single window — FocusLeft is a no-op but must not panic.
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::FocusLeft, 1);
}

#[test]
fn dispatch_buffer_action_buffer_next_single_slot_sets_message() {
    let mut app = App::new(None, false, None, None).unwrap();
    // With a single slot buffer_next is a no-op that sets a status message.
    app.dispatch_action(AppAction::BufferNext, 1);
    assert!(
        app.bus.last_body().is_some(),
        "BufferNext on single slot must push a notification"
    );
}

#[test]
fn dispatch_prompt_action_open_command_prompt_opens_command_field() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::OpenCommandPrompt, 1);
    assert!(
        app.command_field.is_some(),
        "OpenCommandPrompt must open command_field"
    );
}

#[test]
fn dispatch_prompt_action_open_search_prompt_opens_search_field() {
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::OpenSearchPrompt(SearchDir::Forward), 1);
    assert!(
        app.search_field.is_some(),
        "OpenSearchPrompt must open search_field"
    );
}

#[test]
fn dispatch_pending_state_action_begin_pending_replace_sets_state() {
    let mut app = App::new(None, false, None, None).unwrap();
    assert!(app.pending_state.is_none(), "pending_state starts None");
    app.dispatch_action(AppAction::BeginPendingReplace { count: 1 }, 1);
    assert!(
        app.pending_state.is_some(),
        "BeginPendingReplace must set pending_state"
    );
    assert!(
        matches!(
            app.pending_state,
            Some(hjkl_vim::PendingState::Replace { .. })
        ),
        "pending_state must be Replace variant"
    );
}

#[test]
fn dispatch_engine_action_dot_repeat_no_panic_on_empty_buffer() {
    // Empty buffer, no last change — DotRepeat must not panic.
    let mut app = App::new(None, false, None, None).unwrap();
    app.dispatch_action(AppAction::DotRepeat { count: 1 }, 1);
}

#[test]
fn dispatch_action_stays_small() {
    // Regression: dispatch_action body must stay under 100 lines.
    // We locate the function by its signature and count until the first
    // `^    }$` line (the closing brace at 4-space indent).
    // dispatch_action was moved to dispatch.rs as part of the mod.rs split.
    let src = include_str!("../dispatch.rs");
    let start = src
        .find("pub fn dispatch_action")
        .expect("dispatch_action must exist in dispatch.rs");
    let rest = &src[start..];
    // Count lines until and including the closing brace.
    let mut brace_depth = 0usize;
    let mut line_count = 0usize;
    let mut found_open = false;
    for line in rest.lines() {
        line_count += 1;
        for ch in line.chars() {
            match ch {
                '{' => {
                    brace_depth += 1;
                    found_open = true;
                }
                '}' => {
                    brace_depth = brace_depth.saturating_sub(1);
                }
                _ => {}
            }
        }
        if found_open && brace_depth == 0 {
            break;
        }
    }
    assert!(
        line_count < 100,
        "dispatch_action must be < 100 lines, got {line_count}"
    );
}

/// `sync_after_engine_mutation` must append entries to `dirty_rows_log` whose
/// `dirty_gen` matches the buffer's current gen and whose row range contains
/// the row that was edited.
#[test]
fn sync_appends_edit_log_with_correct_dirty_gen() {
    // Open a 5-line buffer.
    let mut app = App::new(None, false, None, None).unwrap();
    seed_buffer(&mut app, "a\nb\nc\nd\ne");
    // Flush any edits from seeding so we start with a clean log.
    app.sync_after_engine_mutation();
    app.active_mut().dirty_rows_log.clear();

    // Enter Insert mode on row 2 and type 'x' — this produces a ContentEdit
    // with start_position.0 == 2.
    app.active_mut().editor.jump_cursor(2, 0);
    app.sync_viewport_from_editor();
    enter_insert(&mut app);
    dik(
        &mut app,
        crossterm::event::KeyEvent::new(
            crossterm::event::KeyCode::Char('x'),
            crossterm::event::KeyModifiers::NONE,
        ),
    );

    // After sync the log must have at least one entry whose row range
    // contains row 2, and whose dirty_gen matches the buffer's current gen.
    let current_dg = app.active().editor.buffer().dirty_gen();
    let log = &app.active().dirty_rows_log;
    assert!(
        !log.is_empty(),
        "dirty_rows_log must have at least one entry after an edit"
    );
    let entry_for_row2 = log
        .iter()
        .find(|(dg, range)| *dg == current_dg && range.contains(&2));
    assert!(
        entry_for_row2.is_some(),
        "dirty_rows_log must have an entry with dirty_gen={current_dg} containing row 2; \
         log={log:?}"
    );
}