egui_kittest: Allow passing state to the app closure

crates/egui_demo_lib/src/demo/text_edit.rs

@@ -121,12 +121,15 @@ mod tests {
 
     #[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);
-            });
-        });
+        let text = "Hello, world!".to_owned();
+        let mut harness = Harness::new_state(
+            move |ctx, text| {
+                CentralPanel::default().show(ctx, |ui| {
+                    ui.text_edit_singleline(text);
+                });
+            },
+            text,
+        );
 
         harness.run();
 
@@ -144,5 +147,6 @@ mod tests {
         harness.run();
         let text_edit = harness.get_by_role(accesskit::Role::TextInput);
         assert_eq!(text_edit.value().as_deref(), Some("Hi there!"));
+        assert_eq!(harness.state(), "Hi there!");
     }
 }

crates/egui_kittest/src/app_kind.rs

@@ -1,11 +1,15 @@
 use egui::Frame;
 
+type AppKindContextState<'a, State> = Box<dyn FnMut(&egui::Context, &mut State) + 'a>;
+type AppKindUiState<'a, State> = Box<dyn FnMut(&mut egui::Ui, &mut State) + 'a>;
 type AppKindContext<'a> = Box<dyn FnMut(&egui::Context) + 'a>;
 type AppKindUi<'a> = Box<dyn FnMut(&mut egui::Ui) + 'a>;
 
-pub(crate) enum AppKind<'a> {
+pub(crate) enum AppKind<'a, State> {
     Context(AppKindContext<'a>),
     Ui(AppKindUi<'a>),
+    ContextState(AppKindContextState<'a, State>),
+    UiState(AppKindUiState<'a, State>),
 }
 
 // TODO(lucasmerlin): These aren't working unfortunately :(
@@ -32,28 +36,29 @@ pub(crate) enum AppKind<'a> {
 //     }
 // }
 
-impl<'a> AppKind<'a> {
-    pub fn run(&mut self, ctx: &egui::Context) -> Option<egui::Response> {
+impl<'a, S> AppKind<'a, S> {
+    pub fn run(
+        &mut self,
+        ctx: &egui::Context,
+        state: &mut S,
+        sizing_pass: bool,
+    ) -> Option<egui::Response> {
         match self {
             AppKind::Context(f) => {
+                debug_assert!(!sizing_pass, "Context closures cannot do a sizing pass");
                 f(ctx);
                 None
             }
-            AppKind::Ui(f) => Some(Self::run_ui(f, ctx, false)),
-        }
-    }
-
-    pub(crate) fn run_sizing_pass(&mut self, ctx: &egui::Context) -> Option<egui::Response> {
-        match self {
-            AppKind::Context(f) => {
-                f(ctx);
+            AppKind::ContextState(f) => {
+                debug_assert!(!sizing_pass, "Context closures cannot do a sizing pass");
+                f(ctx, state);
                 None
             }
-            AppKind::Ui(f) => Some(Self::run_ui(f, ctx, true)),
+            kind_ui => Some(kind_ui.run_ui(ctx, state, sizing_pass)),
         }
     }
 
-    fn run_ui(f: &mut AppKindUi<'a>, ctx: &egui::Context, sizing_pass: bool) -> egui::Response {
+    fn run_ui(&mut self, ctx: &egui::Context, state: &mut S, sizing_pass: bool) -> egui::Response {
         egui::CentralPanel::default()
             .frame(Frame::none())
             .show(ctx, |ui| {
@@ -65,7 +70,11 @@ impl<'a> AppKind<'a> {
                     Frame::central_panel(ui.style())
                         .outer_margin(8.0)
                         .inner_margin(0.0)
-                        .show(ui, |ui| f(ui));
+                        .show(ui, |ui| match self {
+                            AppKind::Ui(f) => f(ui),
+                            AppKind::UiState(f) => f(ui, state),
+                            _ => unreachable!(),
+                        });
                 })
                 .response
             })

crates/egui_kittest/src/builder.rs

@@ -1,23 +1,26 @@
 use crate::app_kind::AppKind;
 use crate::Harness;
 use egui::{Pos2, Rect, Vec2};
+use std::marker::PhantomData;
 
 /// Builder for [`Harness`].
-pub struct HarnessBuilder {
+pub struct HarnessBuilder<S = ()> {
     pub(crate) screen_rect: Rect,
     pub(crate) pixels_per_point: f32,
+    pub(crate) state: PhantomData<S>,
 }
 
-impl Default for HarnessBuilder {
+impl<S> Default for HarnessBuilder<S> {
     fn default() -> Self {
         Self {
             screen_rect: Rect::from_min_size(Pos2::ZERO, Vec2::new(800.0, 600.0)),
             pixels_per_point: 1.0,
+            state: PhantomData,
         }
     }
 }
 
-impl HarnessBuilder {
+impl<S> HarnessBuilder<S> {
     /// Set the size of the window.
     #[inline]
     pub fn with_size(mut self, size: impl Into<Vec2>) -> Self {
@@ -34,6 +37,69 @@ impl HarnessBuilder {
         self
     }
 
+    /// 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.
+    ///
+    /// If you don't need to create Windows / Panels, you can use [`HarnessBuilder::build_ui`] instead.
+    ///
+    /// # Example
+    /// ```rust
+    /// # use egui::CentralPanel;
+    /// # use egui_kittest::{Harness, kittest::Queryable};
+    /// let checked = false;
+    /// let mut harness = Harness::builder()
+    ///     .with_size(egui::Vec2::new(300.0, 200.0))
+    ///     .build_state(|ctx, checked| {
+    ///         CentralPanel::default().show(ctx, |ui| {
+    ///             ui.checkbox(checked, "Check me!");
+    ///         });
+    ///     }, checked);
+    ///
+    /// harness.get_by_name("Check me!").click();
+    /// harness.run();
+    ///
+    /// assert_eq!(*harness.state(), true);
+    /// ```
+    pub fn build_state<'a>(
+        self,
+        app: impl FnMut(&egui::Context, &mut S) + 'a,
+        state: S,
+    ) -> Harness<'a, S> {
+        Harness::from_builder(&self, AppKind::ContextState(Box::new(app)), state)
+    }
+
+    /// Create a new Harness with the given ui closure and a state.
+    ///
+    /// The ui closure will immediately be called once to create the initial ui.
+    ///
+    /// If you need to create Windows / Panels, you can use [`HarnessBuilder::build`] instead.
+    ///
+    /// # Example
+    /// ```rust
+    /// # use egui_kittest::{Harness, kittest::Queryable};
+    /// let mut checked = false;
+    /// let mut harness = Harness::builder()
+    ///     .with_size(egui::Vec2::new(300.0, 200.0))
+    ///     .build_ui_state(|ui, checked| {
+    ///        ui.checkbox(checked, "Check me!");
+    ///     }, checked);
+    ///
+    /// harness.get_by_name("Check me!").click();
+    /// harness.run();
+    ///
+    /// assert_eq!(*harness.state(), true);
+    /// ```
+    pub fn build_ui_state<'a>(
+        self,
+        app: impl FnMut(&mut egui::Ui, &mut S) + 'a,
+        state: S,
+    ) -> Harness<'a, S> {
+        Harness::from_builder(&self, AppKind::UiState(Box::new(app)), state)
+    }
+}
+
+impl HarnessBuilder {
     /// Create a new Harness with the given app closure.
     ///
     /// The app closure will immediately be called once to create the initial ui.
@@ -43,7 +109,7 @@ impl HarnessBuilder {
     /// # Example
     /// ```rust
     /// # use egui::CentralPanel;
-    /// # use egui_kittest::Harness;
+    /// # use egui_kittest::{Harness, kittest::Queryable};
     /// let mut harness = Harness::builder()
     ///     .with_size(egui::Vec2::new(300.0, 200.0))
     ///     .build(|ctx| {
@@ -53,7 +119,7 @@ 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)), ())
     }
 
     /// Create a new Harness with the given ui closure.
@@ -64,14 +130,14 @@ impl HarnessBuilder {
     ///
     /// # Example
     /// ```rust
-    /// # use egui_kittest::Harness;
+    /// # use egui_kittest::{Harness, kittest::Queryable};
     /// let mut harness = Harness::builder()
     ///     .with_size(egui::Vec2::new(300.0, 200.0))
     ///     .build_ui(|ui| {
     ///         ui.label("Hello, world!");
     ///     });
     /// ```
     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)), ())
     }
 }