Add egui_kittest, a test harness for egui

.gitattributes

@@ -1,2 +1,3 @@
 * text=auto eol=lf
 Cargo.lock linguist-generated=false
+**/tests/snapshots/**/*.png filter=lfs diff=lfs merge=lfs -text

.github/workflows/rust.yml

@@ -13,6 +13,8 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
+        with:
+          lfs: true
 
       - uses: dtolnay/rust-toolchain@master
         with:
@@ -60,18 +62,12 @@ jobs:
       - name: cargo check -p test_egui_extras_compilation
         run: cargo check -p test_egui_extras_compilation
 
-      - name: Test doc-tests
-        run: cargo test --doc --all-features
-
       - name: cargo doc --lib
         run: cargo doc --lib --no-deps --all-features
 
       - name: cargo doc --document-private-items
         run: cargo doc --document-private-items --no-deps --all-features
 
-      - name: Test
-        run: cargo test --all-features
-
       - name: clippy
         run: cargo clippy --all-targets --all-features -- -D warnings
 
@@ -222,3 +218,36 @@ jobs:
 
       - name: Check hello_world
         run: cargo check -p hello_world
+
+  # ---------------------------------------------------------------------------
+
+  tests:
+    name: Run tests
+    # We run the tests on macOS because it will run with a actual GPU
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          lfs: true
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: 1.76.0
+
+      - name: Set up cargo cache
+        uses: Swatinem/rust-cache@v2
+
+      - name: Run tests
+        # TODO(lucasmerlin): Enable --all-features (currently this breaks the rendering in the tests because of the `unity` feature)
+        run: cargo test
+
+      - name: Run doc-tests
+        # TODO(lucasmerlin): Enable --all-features (currently this breaks the rendering in the tests because of the `unity` feature)
+        run: cargo test --doc
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: test-results
+          path: "**/tests/snapshots"

.gitignore

@@ -6,3 +6,5 @@
 /.vscode
 /media/*
 .idea/
+**/tests/snapshots/**/*.new.png
+**/tests/snapshots/**/*.diff.png

Cargo.lock

@@ -614,6 +614,12 @@ version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 
+[[package]]
+name = "byteorder-lite"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1fe948ff07f4bd06c30984e69f5b4899c516a3ef74f34df92a2df2ab535495"
+
 [[package]]
 name = "bytes"
 version = "1.5.0"
@@ -818,6 +824,16 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3d7b894f5411737b7867f4827955924d7c254fc9f4d91a6aad6b097804b1018b"
 
+[[package]]
+name = "colored"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cbf2150cce219b664a8a70df7a1f933836724b503f8a413af9365b4dcc4d90b8"
+dependencies = [
+ "lazy_static",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "com"
 version = "0.6.0"
@@ -1097,6 +1113,19 @@ dependencies = [
  "syn 1.0.109",
 ]
 
+[[package]]
+name = "dify"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "11217d469eafa3b809ad84651eb9797ccbb440b4a916d5d85cb1b994e89787f6"
+dependencies = [
+ "anyhow",
+ "colored",
+ "getopts",
+ "image",
+ "rayon",
+]
+
 [[package]]
 name = "digest"
 version = "0.10.7"
@@ -1304,9 +1333,12 @@ dependencies = [
  "criterion",
  "document-features",
  "egui",
+ "egui_demo_lib",
  "egui_extras",
+ "egui_kittest",
  "serde",
  "unicode_names2",
+ "wgpu",
 ]
 
 [[package]]
@@ -1348,6 +1380,20 @@ dependencies = [
  "winit",
 ]
 
+[[package]]
+name = "egui_kittest"
+version = "0.29.1"
+dependencies = [
+ "accesskit_consumer",
+ "dify",
+ "egui",
+ "egui-wgpu",
+ "image",
+ "kittest",
+ "pollster",
+ "wgpu",
+]
+
 [[package]]
 name = "ehttp"
 version = "0.5.0"
@@ -1767,6 +1813,15 @@ dependencies = [
  "windows-targets 0.48.5",
 ]
 
+[[package]]
+name = "getopts"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14dbbfd5c71d70241ecf9e6f13737f7b5ce823821063188d7e46c41d371eebd5"
+dependencies = [
+ "unicode-width",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.10"
@@ -2130,12 +2185,12 @@ dependencies = [
 
 [[package]]
 name = "image"
-version = "0.25.0"
+version = "0.25.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9b4f005360d32e9325029b38ba47ebd7a56f3316df09249368939562d518645"
+checksum = "99314c8a2152b8ddb211f924cdae532d8c5e4c8bb54728e12fff1b0cd5963a10"
 dependencies = [
  "bytemuck",
- "byteorder",
+ "byteorder-lite",
  "color_quant",
  "gif",
  "num-traits",
@@ -2290,6 +2345,16 @@ version = "3.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2db585e1d738fc771bf08a151420d3ed193d9d895a36df7f6f8a9456b911ddc"
 
+[[package]]
+name = "kittest"
+version = "0.1.0"
+source = "git+https://github.com/rerun-io/kittest?branch=impl-debug#240832d5d086ae0a9cf358af9450c0cef16fbeab"
+dependencies = [
+ "accesskit",
+ "accesskit_consumer",
+ "parking_lot",
+]
+
 [[package]]
 name = "kurbo"
 version = "0.9.5"
@@ -2299,6 +2364,12 @@ dependencies = [
  "arrayvec",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.155"

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     "crates/egui_demo_lib",
     "crates/egui_extras",
     "crates/egui_glow",
+    "crates/egui_kittest",
     "crates/egui-wgpu",
     "crates/egui-winit",
     "crates/egui",
@@ -64,6 +65,7 @@ egui_extras = { version = "0.29.1", path = "crates/egui_extras", default-feature
 egui-wgpu = { version = "0.29.1", path = "crates/egui-wgpu", default-features = false }
 egui_demo_lib = { version = "0.29.1", path = "crates/egui_demo_lib", default-features = false }
 egui_glow = { version = "0.29.1", path = "crates/egui_glow", default-features = false }
+egui_kittest = { version = "0.29.1", path = "crates/egui_kittest", default-features = false }
 eframe = { version = "0.29.1", path = "crates/eframe", default-features = false }
 
 ahash = { version = "0.8.11", default-features = false, features = [

crates/egui_demo_lib/Cargo.toml

@@ -55,8 +55,13 @@ serde = { workspace = true, optional = true }
 
 
 [dev-dependencies]
-criterion.workspace = true
+# when running tests we always want to use the `chrono` feature
+egui_demo_lib = { features = ["chrono"], workspace = true }
 
+criterion.workspace = true
+egui_kittest = { workspace = true, features = ["default", "wgpu", "snapshot"] }
+wgpu = { workspace = true, features = ["metal"] }
+egui = { workspace = true, features = ["default_fonts"] }
 
 [[bench]]
 name = "benchmark"

crates/egui_demo_lib/src/demo/demo_app_windows.rs

@@ -377,3 +377,60 @@ fn file_menu_button(ui: &mut Ui) {
         }
     });
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::demo::demo_app_windows::Demos;
+    use egui::Vec2;
+    use egui_kittest::kittest::Queryable;
+    use egui_kittest::try_image_snapshot;
+    use egui_kittest::wgpu::TestRenderer;
+    use egui_kittest::Harness;
+
+    #[test]
+    fn demos_should_match_snapshot() {
+        let demos = Demos::default();
+
+        let mut errors = Vec::new();
+
+        for mut demo in demos.demos {
+            // Remove the emoji from the demo name
+            let name = demo
+                .name()
+                .split_once(' ')
+                .map_or(demo.name(), |(_, name)| name);
+
+            // Widget Gallery needs to be customized (to set a specific date) and has its own test
+            if name == "Widget Gallery" {
+                continue;
+            }
+
+            let mut harness = Harness::new(|ctx| {
+                demo.show(ctx, &mut true);
+            });
+
+            // We need to run the app for multiple frames before all windows have the right size
+            harness.run();
+            harness.run();
+
+            let window = harness.node().children().next().unwrap();
+            // TODO(lucasmerlin): Windows should probably have a label?
+            //let window = harness.get_by_name(name);
+
+            let size = window.raw_bounds().expect("window bounds").size();
+            harness.set_size(Vec2::new(size.width as f32, size.height as f32));
+
+            // We need to run the app for some more frames...
+            harness.run();
+            harness.run();
+
+            let image = TestRenderer::new().render(&harness);
+            let result = try_image_snapshot(&image, &format!("demos/{name}"));
+            if let Err(err) = result {
+                errors.push(err);
+            }
+        }
+
+        assert!(errors.is_empty(), "Errors: {errors:#?}");
+    }
+}

crates/egui_demo_lib/src/demo/text_edit.rs

@@ -112,3 +112,37 @@ impl crate::View for TextEditDemo {
         });
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use egui::{accesskit, CentralPanel};
+    use egui_kittest::kittest::{Key, Queryable};
+    use egui_kittest::Harness;
+
+    #[test]
+    pub fn should_type() {
+        let mut text = "Hello, world!".to_owned();
+        let mut harness = Harness::new(move |ctx| {
+            CentralPanel::default().show(ctx, |ui| {
+                ui.text_edit_singleline(&mut text);
+            });
+        });
+
+        harness.run();
+
+        let text_edit = harness.get_by_role(accesskit::Role::TextInput);
+        assert_eq!(text_edit.value().as_deref(), Some("Hello, world!"));
+
+        text_edit.key_combination(&[Key::Command, Key::A]);
+        text_edit.type_text("Hi ");
+
+        harness.run();
+        harness
+            .get_by_role(accesskit::Role::TextInput)
+            .type_text("there!");
+
+        harness.run();
+        let text_edit = harness.get_by_role(accesskit::Role::TextInput);
+        assert_eq!(text_edit.value().as_deref(), Some("Hi there!"));
+    }
+}

crates/egui_demo_lib/src/demo/widget_gallery.rs

@@ -285,3 +285,38 @@ fn doc_link_label_with_crate<'a>(
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::View;
+    use egui::{CentralPanel, Context, Vec2};
+    use egui_kittest::image_snapshot;
+    use egui_kittest::wgpu::TestRenderer;
+    use egui_kittest::Harness;
+
+    #[test]
+    pub fn should_match_screenshot() {
+        let mut demo = WidgetGallery {
+            // If we don't set a fixed date, the snapshot test will fail.
+            date: Some(chrono::NaiveDate::from_ymd_opt(2024, 1, 1).unwrap()),
+            ..Default::default()
+        };
+        let app = |ctx: &Context| {
+            CentralPanel::default().show(ctx, |ui| {
+                demo.ui(ui);
+            });
+        };
+        let mut harness = Harness::builder()
+            .with_size(Vec2::new(380.0, 550.0))
+            .with_dpi(2.0)
+            .build(app);
+
+        // The first and second frames are slightly different, so we take the second frame
+        harness.run();
+
+        let image = TestRenderer::new().render(&harness);
+
+        image_snapshot(&image, "widget_gallery");
+    }
+}