Refactor example tests to run more efficiently

masonry/Cargo.toml

@@ -75,34 +75,13 @@ profiling = { version = "1.0.15", features = ["profile-with-tracing"] }
 [target.'cfg(target_os = "android")'.dependencies]
 tracing_android_trace = "0.1.0"
 
-[[example]]
-name = "calc_masonry"
-test = true
-
-[[example]]
-name = "custom_widget"
-test = true
-
-[[example]]
-name = "grid_masonry"
-test = true
-
-[[example]]
-name = "hello_masonry"
-test = true
-
 [[example]]
 name = "simple_image"
-test = true
 #required-features = ["image", "png"]
 # This actually enables scraping for all examples, not just this one.
 # However it is possible to set doc-scrape-examples to false for other specific examples.
 doc-scrape-examples = true
 
 [[example]]
-name = "to_do_list"
+name = "tests"
-test = true
-
-[[example]]
-name = "two_textboxes"
 test = true

masonry/examples/calc_masonry.rs

@@ -4,7 +4,7 @@
 //! Simple calculator.
 
 // On Windows platform, don't show a console when opening the app.
-#![windows_subsystem = "windows"]
+#![cfg_attr(not(test), windows_subsystem = "windows")]
 #![allow(
     variant_size_differences,
     clippy::single_match,
@@ -341,7 +341,8 @@ fn flex_row(
         .with_flex_child(w4, 1.0)
 }
 
-fn build_calc() -> impl Widget {
+/// Builds the calculator widget.
+pub fn build_calc() -> impl Widget {
     let display = Label::new(String::new()).with_style(StyleProperty::FontSize(32.));
     Flex::column()
         .gap(0.0)
@@ -423,22 +424,3 @@ fn main() {
     )
     .unwrap();
 }
-
-// --- MARK: TESTS ---
-#[cfg(test)]
-mod tests {
-    use insta::assert_debug_snapshot;
-    use masonry::assert_render_snapshot;
-    use masonry::testing::TestHarness;
-
-    use super::*;
-
-    #[test]
-    fn screenshot_test() {
-        let mut harness = TestHarness::create(build_calc());
-        assert_debug_snapshot!(harness.root_widget());
-        assert_render_snapshot!(harness, "initial_screenshot");
-
-        // TODO - Test clicking buttons
-    }
-}

masonry/examples/custom_widget.rs

@@ -5,7 +5,7 @@
 //! We draw an image, some text, a shape, and a curve.
 
 // On Windows platform, don't show a console when opening the app.
-#![windows_subsystem = "windows"]
+#![cfg_attr(not(test), windows_subsystem = "windows")]
 #![expect(elided_lifetimes_in_paths, reason = "Deferred: Noisy")]
 #![expect(clippy::shadow_unrelated, reason = "Deferred: Noisy")]
 #![expect(clippy::cast_possible_truncation, reason = "Deferred: Noisy")]
@@ -34,7 +34,14 @@ impl AppDriver for Driver {
     fn on_action(&mut self, _ctx: &mut DriverCtx<'_>, _widget_id: WidgetId, _action: Action) {}
 }
 
-struct CustomWidget(String);
+/// A struct that implements the Widget trait.
+///
+/// This struct will be the root widget of the application.
+#[derive(Debug)]
+pub struct CustomWidget(
+    /// A string that will be displayed in the widget.
+    pub String,
+);
 
 impl Widget for CustomWidget {
     fn on_pointer_event(
@@ -202,22 +209,3 @@ fn make_image_data(width: usize, height: usize) -> Vec<u8> {
     }
     result
 }
-
-// --- MARK: TESTS ---
-#[cfg(test)]
-mod tests {
-    use insta::assert_debug_snapshot;
-    use masonry::assert_render_snapshot;
-    use masonry::testing::TestHarness;
-
-    use super::*;
-
-    #[test]
-    fn screenshot_test() {
-        let my_string = "Masonry + Vello".to_string();
-
-        let mut harness = TestHarness::create(CustomWidget(my_string));
-        assert_debug_snapshot!(harness.root_widget());
-        assert_render_snapshot!(harness, "initial_screenshot");
-    }
-}

masonry/examples/grid_masonry.rs

@@ -4,7 +4,7 @@
 //! Shows how to use a grid layout in Masonry.
 
 // On Windows platform, don't show a console when opening the app.
-#![windows_subsystem = "windows"]
+#![cfg_attr(not(test), windows_subsystem = "windows")]
 
 use masonry::app::{AppDriver, DriverCtx};
 use masonry::core::{Action, PointerButton, StyleProperty, WidgetId};
@@ -45,7 +45,8 @@ fn grid_button(params: GridParams) -> Button {
     ))
 }
 
-fn make_grid(grid_spacing: f64) -> Grid {
+/// Create a grid layout with buttons that change the grid spacing.
+pub fn make_grid(grid_spacing: f64) -> Grid {
     let label = SizedBox::new(Prose::from_text_area(
         TextArea::new_immutable("Change spacing by right and left clicking on the buttons")
             .with_style(StyleProperty::FontSize(14.0))
@@ -127,22 +128,3 @@ fn main() {
     )
     .unwrap();
 }
-
-// --- MARK: TESTS ---
-#[cfg(test)]
-mod tests {
-    use insta::assert_debug_snapshot;
-    use masonry::assert_render_snapshot;
-    use masonry::testing::TestHarness;
-
-    use super::*;
-
-    #[test]
-    fn screenshot_test() {
-        let mut harness = TestHarness::create(make_grid(1.0));
-        assert_debug_snapshot!(harness.root_widget());
-        assert_render_snapshot!(harness, "initial_screenshot");
-
-        // TODO - Test clicking buttons
-    }
-}

masonry/examples/readme.md

@@ -1,8 +1,13 @@
 # Masonry examples
 
+## `tests.rs`
+
+This module imports the widgets generated by most other examples and runs screenshot tests to check that the examples render correctly.
+The screenshots below are generated from those tests.
+
 ## `hello_masonry`
 
-Simples possible Masonry app.
+Simplest possible Masonry app.
 
 ## `two_textboxes`
 

masonry/examples/simple_image.rs

@@ -6,7 +6,7 @@
 //! everything behaves.
 
 // On Windows platform, don't show a console when opening the app.
-#![windows_subsystem = "windows"]
+#![cfg_attr(not(test), windows_subsystem = "windows")]
 
 use masonry::app::{AppDriver, DriverCtx};
 use masonry::core::{Action, ObjectFit, WidgetId};
@@ -21,7 +21,8 @@ impl AppDriver for Driver {
     fn on_action(&mut self, _ctx: &mut DriverCtx<'_>, _widget_id: WidgetId, _action: Action) {}
 }
 
-fn make_image() -> Image {
+/// Creates an image widget with a PNG image.
+pub fn make_image() -> Image {
     let image_bytes = include_bytes!("./assets/PicWithAlpha.png");
     let image_data = image::load_from_memory(image_bytes).unwrap().to_rgba8();
     let (width, height) = image_data.dimensions();
@@ -50,20 +51,3 @@ fn main() {
     )
     .unwrap();
 }
-
-// --- MARK: TESTS ---
-#[cfg(test)]
-mod tests {
-    use insta::assert_debug_snapshot;
-    use masonry::assert_render_snapshot;
-    use masonry::testing::TestHarness;
-
-    use super::*;
-
-    #[test]
-    fn screenshot_test() {
-        let mut harness = TestHarness::create(make_image());
-        assert_debug_snapshot!(harness.root_widget());
-        assert_render_snapshot!(harness, "initial_screenshot");
-    }
-}

masonry/examples/snapshots/custom_widget__tests__screenshot_test.snap

@@ -1,6 +0,0 @@
----
-source: masonry/examples/custom_widget.rs
-assertion_line: 195
-expression: harness.root_widget()
----
-CustomWidget

masonry/examples/snapshots/simple_image__tests__screenshot_test.snap

@@ -1,6 +0,0 @@
----
-source: masonry/examples/simple_image.rs
-assertion_line: 65
-expression: harness.root_widget()
----
-Image

masonry/examples/snapshots/tests__tests__calc_masonry_screenshot.snap

@@ -1,6 +1,6 @@
 ---
-source: masonry/examples/calc_masonry.rs
+source: masonry/examples/tests.rs
-assertion_line: 416
+assertion_line: 30
 expression: harness.root_widget()
 ---
 Flex(

masonry/examples/snapshots/tests__tests__custom_widget_screenshot.snap

@@ -0,0 +1,6 @@
+---
+source: masonry/examples/tests.rs
+assertion_line: 41
+expression: harness.root_widget()
+---
+CustomWidget

masonry/examples/snapshots/tests__tests__grid_masonry_screenshot.snap

@@ -1,6 +1,6 @@
 ---
-source: masonry/examples/grid_masonry.rs
+source: masonry/examples/tests.rs
-assertion_line: 142
+assertion_line: 48
 expression: harness.root_widget()
 ---
 Grid(

masonry/examples/snapshots/tests__tests__simple_image_screenshot.snap

@@ -0,0 +1,6 @@
+---
+source: masonry/examples/tests.rs
+assertion_line: 57
+expression: harness.root_widget()
+---
+Image

masonry/examples/snapshots/tests__tests__to_do_list_screenshot.snap

@@ -1,6 +1,6 @@
 ---
-source: masonry/examples/to_do_list.rs
+source: masonry/examples/tests.rs
-assertion_line: 90
+assertion_line: 64
 expression: harness.root_widget()
 ---
 Portal(

masonry/examples/tests.rs

@@ -0,0 +1,73 @@
+// Copyright 2025 the Xilem Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#![allow(missing_docs)]
+
+fn main() {
+    println!("This example is only used to compile other examples.")
+}
+
+#[cfg(test)]
+#[allow(dead_code)]
+#[path = "."]
+pub mod others {
+    pub mod calc_masonry;
+    pub mod custom_widget;
+    pub mod grid_masonry;
+    pub mod simple_image;
+    pub mod to_do_list;
+}
+
+// --- MARK: TESTS ---
+#[cfg(test)]
+mod tests {
+    use insta::assert_debug_snapshot;
+    use masonry::assert_render_snapshot;
+    use masonry::testing::TestHarness;
+
+    use super::others::*;
+
+    #[test]
+    fn calc_masonry_screenshot() {
+        let mut harness = TestHarness::create(calc_masonry::build_calc());
+        assert_debug_snapshot!(harness.root_widget());
+        assert_render_snapshot!(harness, "calc_masonry_initial");
+
+        // TODO - Test clicking buttons
+    }
+
+    #[test]
+    fn custom_widget_screenshot() {
+        let my_string = "Masonry + Vello".to_string();
+
+        let mut harness = TestHarness::create(custom_widget::CustomWidget(my_string));
+        assert_debug_snapshot!(harness.root_widget());
+        assert_render_snapshot!(harness, "custom_widget_initial");
+    }
+
+    #[test]
+    fn grid_masonry_screenshot() {
+        let mut harness = TestHarness::create(grid_masonry::make_grid(1.0));
+        assert_debug_snapshot!(harness.root_widget());
+        assert_render_snapshot!(harness, "grid_masonry_initial");
+
+        // TODO - Test clicking buttons
+    }
+
+    #[test]
+    fn simple_image_screenshot() {
+        let mut harness = TestHarness::create(simple_image::make_image());
+        assert_debug_snapshot!(harness.root_widget());
+        assert_render_snapshot!(harness, "simple_image_initial");
+    }
+
+    #[test]
+    fn to_do_list_screenshot() {
+        let mut harness = TestHarness::create(to_do_list::make_widget_tree());
+        assert_debug_snapshot!(harness.root_widget());
+        assert_render_snapshot!(harness, "to_do_list_initial");
+
+        // TODO - Test clicking buttons
+        // TODO - Test typing text
+    }
+}

masonry/examples/to_do_list.rs

@@ -5,7 +5,7 @@
 //! It does the almost bare minimum while still being useful.
 
 // On Windows platform, don't show a console when opening the app.
-#![windows_subsystem = "windows"]
+#![cfg_attr(not(test), windows_subsystem = "windows")]
 
 use masonry::app::{AppDriver, DriverCtx};
 use masonry::core::{Action, Widget, WidgetId};
@@ -46,7 +46,8 @@ impl AppDriver for Driver {
     }
 }
 
-fn make_widget_tree() -> impl Widget {
+/// Create a widget tree for an empty to-do list.
+pub fn make_widget_tree() -> impl Widget {
     Portal::new(
         Flex::column()
             .with_child(
@@ -75,23 +76,3 @@ fn main() {
     )
     .unwrap();
 }
-
-// --- MARK: TESTS ---
-#[cfg(test)]
-mod tests {
-    use insta::assert_debug_snapshot;
-    use masonry::assert_render_snapshot;
-    use masonry::testing::TestHarness;
-
-    use super::*;
-
-    #[test]
-    fn screenshot_test() {
-        let mut harness = TestHarness::create(make_widget_tree());
-        assert_debug_snapshot!(harness.root_widget());
-        assert_render_snapshot!(harness, "initial_screenshot");
-
-        // TODO - Test clicking buttons
-        // TODO - Test typing text
-    }
-}