test: add screen snapshot test infrastructure

- Add screen_snapshot_test! macro for easy test creation
- Support for key event simulation in tests
- EmptyMockProvider for screens without data dependencies
- Organize helpers in dedicated directory

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: unhappychoice

tests/integration/mod.rs

@@ -3,6 +3,7 @@ pub mod comment_processing_tests;
 pub mod indent_treesitter_tests;
 pub mod languages;
 pub mod missing_ascii_art_test;
+pub mod screens;
 
 use gittype::domain::models::languages::*;
 use gittype::domain::models::{Challenge, CodeChunk, ExtractionOptions, Language, Languages};

tests/integration/screens/helpers/mod.rs

@@ -0,0 +1,4 @@
+#[macro_use]
+mod test_helpers;
+
+pub use test_helpers::*;

tests/integration/screens/helpers/test_helpers.rs

@@ -0,0 +1,108 @@
+use gittype::presentation::game::models::ScreenDataProvider;
+use gittype::Result;
+
+/// Empty mock provider for screens that don't need data
+pub struct EmptyMockProvider;
+
+impl ScreenDataProvider for EmptyMockProvider {
+    fn provide(&self) -> Result<Box<dyn std::any::Any>> {
+        Ok(Box::new(()))
+    }
+}
+
+/// Helper macro to create snapshot tests for screens using ratatui TestBackend
+#[macro_export]
+macro_rules! screen_snapshot_test {
+    // Version with custom provider
+    ($test_name:ident, $screen_type:ty, $screen_init:expr, provider = $provider:expr) => {
+        #[test]
+        fn $test_name() {
+            use gittype::presentation::game::Screen;
+            use gittype::presentation::game::models::ScreenDataProvider;
+            use ratatui::backend::TestBackend;
+            use ratatui::Terminal;
+
+            let mut screen: $screen_type = $screen_init;
+
+            // Initialize screen with data from the provided mock provider
+            let data = $provider.provide().unwrap();
+            let _ = screen.init_with_data(data);
+
+            // Create a test backend with a reasonable terminal size
+            let backend = TestBackend::new(120, 40);
+            let mut terminal = Terminal::new(backend).unwrap();
+
+            terminal
+                .draw(|frame| {
+                    screen.render_ratatui(frame).unwrap();
+                })
+                .unwrap();
+
+            // Get the rendered buffer as a string representation
+            let buffer = terminal.backend().buffer();
+            let mut output = String::new();
+            for y in 0..buffer.area.height {
+                for x in 0..buffer.area.width {
+                    let cell = &buffer[(x, y)];
+                    output.push_str(cell.symbol());
+                }
+                output.push('\n');
+            }
+            insta::assert_snapshot!(output);
+        }
+    };
+
+    // Version without custom provider (uses EmptyMockProvider)
+    ($test_name:ident, $screen_type:ty, $screen_init:expr) => {
+        screen_snapshot_test!($test_name, $screen_type, $screen_init, provider = $crate::integration::screens::helpers::EmptyMockProvider);
+    };
+
+    // Version with key events
+    ($test_name:ident, $screen_type:ty, $screen_init:expr, provider = $provider:expr, keys = [$($key:expr),*]) => {
+        #[test]
+        fn $test_name() {
+            use gittype::presentation::game::Screen;
+            use gittype::presentation::game::models::ScreenDataProvider;
+            use ratatui::backend::TestBackend;
+            use ratatui::Terminal;
+
+            let mut screen: $screen_type = $screen_init;
+
+            // Initialize screen with data from the provided mock provider
+            let data = $provider.provide().unwrap();
+            let _ = screen.init_with_data(data);
+
+            // Handle key events
+            $(
+                let _ = screen.handle_key_event($key);
+            )*
+
+            // Create a test backend with a reasonable terminal size
+            let backend = TestBackend::new(120, 40);
+            let mut terminal = Terminal::new(backend).unwrap();
+
+            terminal
+                .draw(|frame| {
+                    screen.render_ratatui(frame).unwrap();
+                })
+                .unwrap();
+
+            // Get the rendered buffer as a string representation
+            let buffer = terminal.backend().buffer();
+            let mut output = String::new();
+            for y in 0..buffer.area.height {
+                for x in 0..buffer.area.width {
+                    let cell = &buffer[(x, y)];
+                    output.push_str(cell.symbol());
+                }
+                output.push('\n');
+            }
+            insta::assert_snapshot!(output);
+        }
+    };
+
+    // Version with key events but without provider
+    ($test_name:ident, $screen_type:ty, $screen_init:expr, keys = [$($key:expr),*]) => {
+        screen_snapshot_test!($test_name, $screen_type, $screen_init, provider = $crate::integration::screens::helpers::EmptyMockProvider, keys = [$($key),*]);
+    };
+}