pdfcraft/crates/ui-egui/tests/ui_group/theme.rs

//! Theme preferences stay in sync across both menus, OS changes and saved settings.

use egui_kittest::Harness;
use egui_kittest::kittest::Queryable;
use pdfcraft_ui_egui::PdfCraftApp;
use pdfcraft_ui_egui::theme::{ThemeKind, ThemePreference, Tokens};

fn harness() -> Harness<'static, PdfCraftApp> {
    let mut h = Harness::builder().with_size(egui::vec2(1100.0, 800.0)).build_eframe(|_cc| {
        let mut app = PdfCraftApp::new();
        app.set_option("language", "en").unwrap();
        app
    });
    h.input_mut().system_theme = Some(egui::Theme::Dark);
    h.run_steps(4);
    h
}

fn assert_theme(h: &Harness<'static, PdfCraftApp>, preference: ThemePreference, kind: ThemeKind) {
    assert_eq!(h.state().theme_preference, preference);
    assert_eq!(h.state().theme, kind);
    assert_eq!(Tokens::get(&h.ctx).kind, kind);
    assert_eq!(h.ctx.global_style().visuals.dark_mode, kind == ThemeKind::Dark);
    assert_eq!(h.ctx.options(|o| o.theme_preference), egui::ThemePreference::System);
    for branch in [egui::Theme::Light, egui::Theme::Dark] {
        let style = h.ctx.style_of(branch);
        assert_eq!(style.visuals.dark_mode, kind == ThemeKind::Dark);
        assert_eq!(style.visuals.panel_fill, Tokens::for_kind(kind).panel);
    }
}

/// A click on the title bar's theme button cycles Light, Dark, System.
fn click_toolbar(h: &mut Harness<'static, PdfCraftApp>, label: &str) {
    h.get_by_label(&format!("Display theme: {label}")).click();
    h.run_steps(3);
}

fn open_view_menu(h: &mut Harness<'static, PdfCraftApp>) {
    h.get_by_label("Menu").click();
    h.run_steps(2);
    h.get_by_label("View ⏵").hover();
    h.run_steps(3);
    assert!(h.query_by_label("Switch light / dark theme").is_none());
    h.get_by_label("Display theme ⏵").hover();
    h.run_steps(3);
    for choice in ["Use system setting", "Light gray", "Dark gray"] {
        h.get_by_label(choice);
    }
}

#[test]
fn toolbar_and_view_menu_share_three_state_preferences() {
    let mut h = harness();
    // Explicit light wins even on a dark desktop, including egui's popup style.
    assert_theme(&h, ThemePreference::Light, ThemeKind::Light);
    click_toolbar(&mut h, "Light gray");
    assert_theme(&h, ThemePreference::Dark, ThemeKind::Dark);
    click_toolbar(&mut h, "Dark gray");
    assert_theme(&h, ThemePreference::System, ThemeKind::Dark);

    open_view_menu(&mut h);
    h.get_by_label("Light gray").click();
    h.run_steps(3);
    assert_theme(&h, ThemePreference::Light, ThemeKind::Light);
    click_toolbar(&mut h, "Light gray");
    assert_theme(&h, ThemePreference::Dark, ThemeKind::Dark);

    open_view_menu(&mut h);
    h.get_by_label("Use system setting").click();
    h.run_steps(3);
    assert_theme(&h, ThemePreference::System, ThemeKind::Dark);
    h.input_mut().system_theme = Some(egui::Theme::Light);
    h.run_steps(3);
    assert_theme(&h, ThemePreference::System, ThemeKind::Light);
    click_toolbar(&mut h, "Use system setting");
    click_toolbar(&mut h, "Light gray");
    // A manual choice exits system mode and survives subsequent OS changes.
    h.input_mut().system_theme = Some(egui::Theme::Dark);
    h.run_steps(2);
    h.input_mut().system_theme = Some(egui::Theme::Light);
    h.run_steps(2);
    assert_theme(&h, ThemePreference::Dark, ThemeKind::Dark);
}

#[test]
fn saved_preferences_restore_with_legacy_light_dark_settings() {
    for (value, preference) in [("light", ThemePreference::Light), ("dark", ThemePreference::Dark), ("system", ThemePreference::System)] {
        let mut app = PdfCraftApp::new();
        app.set_option("language", "en").unwrap();
        app.set_option("theme", value).unwrap();
        let saved = app.persist();
        let mut restored = PdfCraftApp::new();
        restored.set_option("language", "en").unwrap();
        restored.restore(&saved);
        assert_eq!(restored.theme_preference, preference);
    }
    let mut app = PdfCraftApp::new();
    app.set_option("language", "en").unwrap();
    app.restore(r#"{"theme":"Dark"}"#);
    assert_eq!(app.theme_preference, ThemePreference::Dark);
    assert_eq!(app.theme, ThemeKind::Dark);
    app.restore(r#"{"theme":"Light"}"#);
    assert_eq!(app.theme_preference, ThemePreference::Light);
    assert_eq!(app.theme, ThemeKind::Light);
    app.restore(r#"{"theme":"System"}"#);
    app.restore(r#"{"theme":"Purple"}"#);
    assert_eq!(app.theme_preference, ThemePreference::System);
}

#[test]
fn commands_and_options_apply_before_the_first_frame() {
    let mut app = PdfCraftApp::new();
    app.set_option("language", "en").unwrap();
    app.run_command("view.theme.dark");
    assert_eq!(app.theme_preference, ThemePreference::Dark);
    assert_eq!(app.theme, ThemeKind::Dark);
    app.run_command("view.theme.system");
    assert_eq!(app.theme_preference, ThemePreference::System);
    assert_eq!(app.theme, ThemeKind::Light);
    // The existing palette/control toggle also goes through the preference setter.
    app.run_command("view.theme");
    assert_eq!(app.theme_preference, ThemePreference::Dark);
    assert_eq!(app.theme, ThemeKind::Dark);
    app.run_command("view.theme.light");
    app.set_option("theme", "dark").unwrap();
    assert!(app.set_option("theme", "purple").unwrap_err().contains("light, dark, or system"));
    assert_eq!(app.theme_preference, ThemePreference::Dark);
    assert_eq!(app.theme, ThemeKind::Dark);
}

#[test]
fn restored_system_tracks_native_input_without_rewriting_saved_preference() {
    let mut h = Harness::builder().with_size(egui::vec2(1100.0, 800.0)).build_eframe(|_cc| {
        let mut app = PdfCraftApp::new();
        app.set_option("language", "en").unwrap();
        app.restore(r#"{"theme":"System"}"#);
        app
    });
    for (input, expected) in [
        (Some(egui::Theme::Dark), ThemeKind::Dark),
        (Some(egui::Theme::Light), ThemeKind::Light),
        (None, ThemeKind::Light),
        (Some(egui::Theme::Dark), ThemeKind::Dark),
    ] {
        h.input_mut().system_theme = input;
        h.run_steps(3);
        assert_theme(&h, ThemePreference::System, expected);
        assert_eq!(serde_json::from_str::<serde_json::Value>(&h.state().persist()).unwrap()["theme"], "System");
    }
    for (manual, expected) in [(ThemePreference::Light, ThemeKind::Light), (ThemePreference::Dark, ThemeKind::Dark)] {
        h.state_mut().set_theme_preference(manual);
        for input in [Some(egui::Theme::Dark), Some(egui::Theme::Light), None] {
            h.input_mut().system_theme = input;
            h.run_steps(3);
            assert_theme(&h, manual, expected);
        }
    }
}

#[test]
fn unknown_system_uses_light_after_a_manual_dark_choice() {
    let mut app = PdfCraftApp::new();
    app.set_theme_preference(ThemePreference::Dark);
    app.set_theme_preference(ThemePreference::System);
    assert_eq!(app.theme, ThemeKind::Light);
    assert_eq!(serde_json::from_str::<serde_json::Value>(&app.persist()).unwrap()["theme"], "System");
}

#[test]
fn native_appearance_remains_inherited_for_every_saved_choice() {
    #[derive(Clone)]
    struct NativeCommands(std::sync::Arc<std::sync::Mutex<Vec<egui::SystemTheme>>>);
    impl egui::Plugin for NativeCommands {
        fn debug_name(&self) -> &'static str {
            "theme-command-proof"
        }
        fn output_hook(&mut self, _ctx: &egui::Context, output: &mut egui::FullOutput) {
            for command in output.viewport_output.values().flat_map(|v| &v.commands) {
                if let egui::ViewportCommand::SetTheme(theme) = command {
                    self.0.lock().unwrap().push(*theme);
                }
            }
        }
    }
    for preference in [ThemePreference::System, ThemePreference::Light, ThemePreference::Dark] {
        let commands = NativeCommands(Default::default());
        let observed = commands.clone();
        let mut h = Harness::builder().with_size(egui::vec2(1100.0, 800.0)).build_eframe(move |cc| {
            cc.egui_ctx.add_plugin(commands);
            let mut app = PdfCraftApp::new();
            app.set_option("language", "en").unwrap();
            app.set_theme_preference(preference);
            app
        });
        h.input_mut().system_theme = Some(egui::Theme::Light);
        h.run_steps(3);
        h.input_mut().system_theme = Some(egui::Theme::Dark);
        h.run_steps(3);
        // Observe the actual app's startup and later viewport output. This proves
        // native window intent, not operating-system ThemeChanged delivery.
        let commands = observed.0.lock().unwrap();
        assert!(!commands.is_empty());
        assert!(commands.iter().all(|theme| *theme == egui::SystemTheme::SystemDefault), "{commands:?}");
        assert_eq!(h.ctx.options(|o| o.theme_preference), egui::ThemePreference::System);
    }
}