Add Harness::new_eframe and TestRenderer trait (#5539)

Co-authored-by: Andreas Reich <r_andreas2@web.de>

crates/egui_demo_app/Cargo.toml

@@ -93,3 +93,6 @@ rfd = { version = "0.15", optional = true }
 wasm-bindgen = "=0.2.95"
 wasm-bindgen-futures.workspace = true
 web-sys.workspace = true
+
+[dev-dependencies]
+egui_kittest = { workspace = true, features = ["eframe", "snapshot", "wgpu"] }

crates/egui_demo_app/src/apps/image_viewer.rs

@@ -54,8 +54,9 @@ impl eframe::App for ImageViewer {
     fn update(&mut self, ctx: &egui::Context, _: &mut eframe::Frame) {
         egui::TopBottomPanel::new(TopBottomSide::Top, "url bar").show(ctx, |ui| {
             ui.horizontal_centered(|ui| {
-                ui.label("URI:");
-                ui.text_edit_singleline(&mut self.uri_edit_text);
+                let label = ui.label("URI:");
+                ui.text_edit_singleline(&mut self.uri_edit_text)
+                    .labelled_by(label.id);
                 if ui.small_button("✔").clicked() {
                     ctx.forget_image(&self.current_uri);
                     self.uri_edit_text = self.uri_edit_text.trim().to_owned();

crates/egui_demo_app/src/lib.rs

@@ -6,7 +6,7 @@ mod backend_panel;
 mod frame_history;
 mod wrap_app;
 
-pub use wrap_app::WrapApp;
+pub use wrap_app::{Anchor, WrapApp};
 
 /// Time of day as seconds since midnight. Used for clock in demo app.
 pub(crate) fn seconds_since_midnight() -> f64 {

crates/egui_demo_app/src/wrap_app.rs

@@ -38,6 +38,7 @@ impl eframe::App for DemoApp {
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct FractalClockApp {
     fractal_clock: crate::apps::FractalClock,
+    pub mock_time: Option<f64>,
 }
 
 impl eframe::App for FractalClockApp {
@@ -46,7 +47,7 @@ impl eframe::App for FractalClockApp {
             .frame(egui::Frame::dark_canvas(&ctx.style()))
             .show(ctx, |ui| {
                 self.fractal_clock
-                    .ui(ui, Some(crate::seconds_since_midnight()));
+                    .ui(ui, self.mock_time.or(Some(crate::seconds_since_midnight())));
             });
     }
 }
@@ -77,7 +78,7 @@ impl eframe::App for ColorTestApp {
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
-enum Anchor {
+pub enum Anchor {
     Demo,
 
     EasyMarkEditor,
@@ -161,7 +162,7 @@ pub struct State {
     http: crate::apps::HttpApp,
     #[cfg(feature = "image_viewer")]
     image_viewer: crate::apps::ImageViewer,
-    clock: FractalClockApp,
+    pub clock: FractalClockApp,
     rendering_test: ColorTestApp,
 
     selected_anchor: Anchor,
@@ -170,7 +171,7 @@ pub struct State {
 
 /// Wraps many demo/test apps into one.
 pub struct WrapApp {
-    state: State,
+    pub state: State,
 
     #[cfg(any(feature = "glow", feature = "wgpu"))]
     custom3d: Option<crate::apps::Custom3d>,
@@ -203,7 +204,9 @@ impl WrapApp {
         slf
     }
 
-    fn apps_iter_mut(&mut self) -> impl Iterator<Item = (&str, Anchor, &mut dyn eframe::App)> {
+    pub fn apps_iter_mut(
+        &mut self,
+    ) -> impl Iterator<Item = (&'static str, Anchor, &mut dyn eframe::App)> {
         let mut vec = vec![
             (
                 "✨ Demos",

crates/egui_demo_app/tests/snapshots/clock.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7c05cc3d48242e46a391af34cb56f72de7933bf2cead009b6cd477c21867a84e
+size 327802

crates/egui_demo_app/tests/snapshots/custom3d.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:61212e30fe1fecf5891ddad6ac795df510bfad76b21a7a8a13aa024fdad6d05e
+size 93118

crates/egui_demo_app/tests/snapshots/easymarkeditor.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7bcf6e2977bed682d7bdaa0b6a6786e528662dd0791d2e6f83cf1b4852035838
+size 182833

crates/egui_demo_app/tests/snapshots/imageviewer.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e6cc6ff64eb73ddac89ecdacd07c2176f3ab952c0db4593fccf6d11f155ec392
+size 103100

crates/egui_demo_app/tests/test_demo_app.rs

@@ -0,0 +1,78 @@
+use egui::accesskit::Role;
+use egui::Vec2;
+use egui_demo_app::{Anchor, WrapApp};
+use egui_kittest::kittest::Queryable;
+
+#[test]
+fn test_demo_app() {
+    let mut harness = egui_kittest::Harness::builder()
+        .with_size(Vec2::new(900.0, 600.0))
+        .wgpu()
+        .build_eframe(|cc| WrapApp::new(cc));
+
+    let app = harness.state_mut();
+
+    // Mock the fractal clock time so snapshots are consistent.
+    app.state.clock.mock_time = Some(36383.0);
+
+    let apps = app
+        .apps_iter_mut()
+        .map(|(name, anchor, _)| (name, anchor))
+        .collect::<Vec<_>>();
+
+    #[cfg(feature = "wgpu")]
+    assert!(
+        apps.iter()
+            .any(|(_, anchor)| matches!(anchor, Anchor::Custom3d)),
+        "Expected to find the Custom3d app.",
+    );
+
+    let mut results = vec![];
+
+    for (name, anchor) in apps {
+        harness.get_by_role_and_label(Role::Button, name).click();
+
+        match anchor {
+            // The widget gallery demo shows the current date, so we can't use it for snapshot testing
+            Anchor::Demo => {
+                continue;
+            }
+            // This is already tested extensively elsewhere
+            Anchor::Rendering => {
+                continue;
+            }
+            // We don't want to rely on a network connection for tests
+            #[cfg(feature = "http")]
+            Anchor::Http => {
+                continue;
+            }
+            // Load a local image where we know it exists and loads quickly
+            #[cfg(feature = "image_viewer")]
+            Anchor::ImageViewer => {
+                harness.run();
+
+                harness
+                    .get_by_role_and_label(Role::TextInput, "URI:")
+                    .focus();
+                harness.press_key_modifiers(egui::Modifiers::COMMAND, egui::Key::A);
+
+                harness
+                    .get_by_role_and_label(Role::TextInput, "URI:")
+                    .type_text("file://../eframe/data/icon.png");
+
+                harness.get_by_role_and_label(Role::Button, "✔").click();
+            }
+            _ => {}
+        }
+
+        harness.run();
+
+        if let Err(e) = harness.try_snapshot(&anchor.to_string()) {
+            results.push(e);
+        }
+    }
+
+    if let Some(error) = results.first() {
+        panic!("{error}");
+    }
+}