Add Harness::builder and add README.md

crates/egui_demo_lib/src/demo/demo_app_windows.rs

@@ -383,7 +383,7 @@ mod tests {
     use crate::demo::demo_app_windows::Demos;
     use egui::Vec2;
     use egui_kittest::kittest::Queryable;
-    use egui_kittest::snapshot::try_image_snapshot;
+    use egui_kittest::try_image_snapshot;
     use egui_kittest::wgpu::TestRenderer;
     use egui_kittest::Harness;
 
@@ -406,14 +406,13 @@ mod tests {
             // We need to run the app for multiple frames before all windows have the right size
             harness.run();
             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 = harness.with_size(Vec2::new(size.width as f32, size.height as f32));
+            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();

crates/egui_demo_lib/src/demo/widget_gallery.rs

@@ -291,7 +291,7 @@ mod tests {
     use super::*;
     use crate::View;
     use egui::{CentralPanel, Context, Vec2};
-    use egui_kittest::snapshot::image_snapshot;
+    use egui_kittest::image_snapshot;
     use egui_kittest::wgpu::TestRenderer;
     use egui_kittest::Harness;
 
@@ -303,10 +303,12 @@ mod tests {
                 demo.ui(ui);
             });
         };
-        let mut harness = Harness::new(app)
+        let mut harness = Harness::builder()
             .with_size(Vec2::new(380.0, 550.0))
-            .with_dpi(2.0);
+            .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);

crates/egui_kittest/README.md

@@ -0,0 +1,35 @@
+# egui_kittest 
+
+Ui testing library for egui, based on [kittest](https://github.com/rerun-io/kittest) (a AccessKit based testing library).
+
+```rust
+use egui::accesskit::{Role, Toggled};
+use egui::{CentralPanel, Context, TextEdit, Vec2};
+use egui_kittest::Harness;
+use kittest::Queryable;
+use std::cell::RefCell;
+
+fn main() {
+    let mut checked = false;
+    let app = |ctx: &Context| {
+        CentralPanel::default().show(ctx, |ui| {
+            ui.checkbox(&mut checked, "Check me!");
+        });
+    };
+
+    let mut harness = Harness::builder().with_size(egui::Vec2::new(200.0, 100.0)).build(app);
+
+    let checkbox = harness.get_by_name("Check me!");
+    assert_eq!(checkbox.toggled(), Some(Toggled::False));
+    checkbox.click();
+
+    harness.run();
+
+    let checkbox = harness.get_by_name("Check me!");
+    assert_eq!(checkbox.toggled(), Some(Toggled::True));
+
+    // You can even render the ui and do image snapshot tests
+    #[cfg(all(feature = "wgpu", feature = "snapshot"))]
+    egui_kittest::image_snapshot(&egui_kittest::wgpu::TestRenderer::new().render(&harness), "readme_example");
+}
+```

crates/egui_kittest/src/builder.rs

@@ -0,0 +1,33 @@
+use crate::Harness;
+use egui::{Pos2, Rect, Vec2};
+
+pub struct HarnessBuilder {
+    pub(crate) screen_rect: Rect,
+    pub(crate) dpi: f32,
+}
+
+impl Default for HarnessBuilder {
+    fn default() -> Self {
+        Self {
+            screen_rect: Rect::from_min_size(Pos2::ZERO, Vec2::new(800.0, 600.0)),
+            dpi: 1.0,
+        }
+    }
+}
+
+impl HarnessBuilder {
+    pub fn with_size(mut self, size: Vec2) -> Self {
+        self.screen_rect.set_width(size.x);
+        self.screen_rect.set_height(size.y);
+        self
+    }
+
+    pub fn with_dpi(mut self, dpi: f32) -> Self {
+        self.dpi = dpi;
+        self
+    }
+
+    pub fn build<'a>(self, app: impl FnMut(&egui::Context) + 'a) -> Harness<'a> {
+        Harness::from_builder(&self, app)
+    }
+}