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

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

crates/egui_kittest/src/builder.rs

@@ -1,5 +1,6 @@
 use crate::app_kind::AppKind;
-use crate::Harness;
+use crate::wgpu::WgpuTestRenderer;
+use crate::{Harness, LazyRenderer, TestRenderer};
 use egui::{Pos2, Rect, Vec2};
 use std::marker::PhantomData;
 
@@ -8,6 +9,7 @@ pub struct HarnessBuilder<State = ()> {
     pub(crate) screen_rect: Rect,
     pub(crate) pixels_per_point: f32,
     pub(crate) state: PhantomData<State>,
+    pub(crate) renderer: Box<dyn TestRenderer>,
 }
 
 impl<State> Default for HarnessBuilder<State> {
@@ -16,6 +18,7 @@ impl<State> Default for HarnessBuilder<State> {
             screen_rect: Rect::from_min_size(Pos2::ZERO, Vec2::new(800.0, 600.0)),
             pixels_per_point: 1.0,
             state: PhantomData,
+            renderer: Box::new(LazyRenderer::default()),
         }
     }
 }
@@ -37,6 +40,29 @@ impl<State> HarnessBuilder<State> {
         self
     }
 
+    /// Set the [`TestRenderer`] to use for rendering.
+    ///
+    /// By default, a [`LazyRenderer`] is used.
+    #[inline]
+    pub fn renderer(mut self, renderer: impl TestRenderer + 'static) -> Self {
+        self.renderer = Box::new(renderer);
+        self
+    }
+
+    /// Enable wgpu rendering with a default setup suitable for testing.
+    ///
+    /// This sets up a [`WgpuTestRenderer`] with the default setup.
+    #[cfg(feature = "wgpu")]
+    pub fn wgpu(self) -> Self {
+        self.renderer(WgpuTestRenderer::default())
+    }
+
+    /// Enable wgpu rendering with the given setup.
+    #[cfg(feature = "wgpu")]
+    pub fn wgpu_setup(self, setup: egui_wgpu::WgpuSetup) -> Self {
+        self.renderer(WgpuTestRenderer::from_setup(setup))
+    }
+
     /// Create a new Harness with the given app closure and a state.
     ///
     /// The app closure will immediately be called once to create the initial ui.
@@ -66,7 +92,7 @@ impl<State> HarnessBuilder<State> {
         app: impl FnMut(&egui::Context, &mut State) + 'a,
         state: State,
     ) -> Harness<'a, State> {
-        Harness::from_builder(&self, AppKind::ContextState(Box::new(app)), state)
+        Harness::from_builder(self, AppKind::ContextState(Box::new(app)), state, None)
     }
 
     /// Create a new Harness with the given ui closure and a state.
@@ -95,7 +121,30 @@ impl<State> HarnessBuilder<State> {
         app: impl FnMut(&mut egui::Ui, &mut State) + 'a,
         state: State,
     ) -> Harness<'a, State> {
-        Harness::from_builder(&self, AppKind::UiState(Box::new(app)), state)
+        Harness::from_builder(self, AppKind::UiState(Box::new(app)), state, None)
+    }
+
+    /// Create a new [Harness] from the given eframe creation closure.
+    /// The app can be accessed via the [`Harness::state`] / [`Harness::state_mut`] methods.
+    #[cfg(feature = "eframe")]
+    pub fn build_eframe<'a>(
+        self,
+        build: impl FnOnce(&mut eframe::CreationContext<'a>) -> State,
+    ) -> Harness<'a, State>
+    where
+        State: eframe::App,
+    {
+        let ctx = egui::Context::default();
+
+        let mut cc = eframe::CreationContext::_new_kittest(ctx.clone());
+        let mut frame = eframe::Frame::_new_kittest();
+
+        self.renderer.setup_eframe(&mut cc, &mut frame);
+
+        let app = build(&mut cc);
+
+        let kind = AppKind::Eframe((|state| state, frame));
+        Harness::from_builder(self, kind, app, Some(ctx))
     }
 }
 
@@ -119,7 +168,7 @@ impl HarnessBuilder {
     ///     });
     /// ```
     pub fn build<'a>(self, app: impl FnMut(&egui::Context) + 'a) -> Harness<'a> {
-        Harness::from_builder(&self, AppKind::Context(Box::new(app)), ())
+        Harness::from_builder(self, AppKind::Context(Box::new(app)), (), None)
     }
 
     /// Create a new Harness with the given ui closure.
@@ -138,6 +187,6 @@ impl HarnessBuilder {
     ///     });
     /// ```
     pub fn build_ui<'a>(self, app: impl FnMut(&mut egui::Ui) + 'a) -> Harness<'a> {
-        Harness::from_builder(&self, AppKind::Ui(Box::new(app)), ())
+        Harness::from_builder(self, AppKind::Ui(Box::new(app)), (), None)
     }
 }