test: Implemented UI snapshot tests

src/ui/ui_test_utils.rs

@@ -0,0 +1,126 @@
+#[cfg(test)]
+#[allow(dead_code)]
+pub mod test_utils {
+  use ratatui::Frame;
+  use ratatui::Terminal;
+  use ratatui::backend::TestBackend;
+  use ratatui::buffer::Buffer;
+
+  use crate::app::App;
+
+  pub fn create_test_backend(width: u16, height: u16) -> TestBackend {
+    TestBackend::new(width, height)
+  }
+
+  pub fn create_test_terminal(width: u16, height: u16) -> Terminal<TestBackend> {
+    let backend = create_test_backend(width, height);
+    Terminal::new(backend).unwrap()
+  }
+
+  /// Renders a UI component and returns the output as a string
+  ///
+  /// # Arguments
+  /// * `width` - Terminal width in columns
+  /// * `height` - Terminal height in rows
+  /// * `render_fn` - Function that renders to the frame
+  ///
+  /// # Example
+  /// ```rust
+  /// let output = render_to_string(120, 30, |f| {
+  ///   Block::default().title("Test").render(f.area(), f.buffer_mut());
+  /// });
+  /// ```
+  pub fn render_to_string<F>(width: u16, height: u16, mut render_fn: F) -> String
+  where
+    F: FnMut(&mut Frame),
+  {
+    let mut terminal = create_test_terminal(width, height);
+
+    terminal
+      .draw(|f| {
+        render_fn(f);
+      })
+      .unwrap();
+
+    buffer_to_string(terminal.backend().buffer(), width, height)
+  }
+
+  /// Renders a UI component with an App instance and returns the output as a string
+  ///
+  /// This is the primary helper for testing UI components that need app state.
+  ///
+  /// # Arguments
+  /// * `width` - Terminal width in columns (typically 120)
+  /// * `height` - Terminal height in rows (typically 30)
+  /// * `app` - Mutable reference to App instance
+  /// * `render_fn` - Function that renders to the frame with app
+  ///
+  /// # Example
+  /// ```rust
+  /// let mut app = App::test_default();
+  /// app.push_navigation_stack(ActiveRadarrBlock::Movies.into());
+  ///
+  /// let output = render_to_string_with_app(120, 30, &mut app, |f, app| {
+  ///   LibraryUi::draw(f, app, f.area());
+  /// });
+  ///
+  /// insta::assert_snapshot!(output);
+  /// ```
+  pub fn render_to_string_with_app<F>(
+    width: u16,
+    height: u16,
+    app: &mut App,
+    mut render_fn: F,
+  ) -> String
+  where
+    F: FnMut(&mut Frame, &mut App),
+  {
+    let mut terminal = create_test_terminal(width, height);
+
+    terminal
+      .draw(|f| {
+        render_fn(f, app);
+      })
+      .unwrap();
+
+    buffer_to_string(terminal.backend().buffer(), width, height)
+  }
+
+  fn buffer_to_string(buffer: &Buffer, width: u16, height: u16) -> String {
+    let mut result = String::new();
+
+    for y in 0..height {
+      for x in 0..width {
+        let cell = buffer.cell((x, y)).expect("Cell should exist");
+        result.push_str(cell.symbol());
+      }
+      if y < height - 1 {
+        result.push('\n');
+      }
+    }
+
+    result
+  }
+
+  pub fn output_contains(output: &str, text: &str) -> bool {
+    output.contains(text)
+  }
+
+  pub fn output_contains_all(output: &str, texts: &[&str]) -> bool {
+    texts.iter().all(|text| output.contains(text))
+  }
+
+  pub fn count_lines(output: &str) -> usize {
+    output.lines().count()
+  }
+
+  pub fn verify_dimensions(output: &str, max_width: usize, max_height: usize) -> bool {
+    let lines: Vec<&str> = output.lines().collect();
+
+    if lines.len() > max_height {
+      return false;
+    }
+
+    lines.iter().all(|line| line.chars().count() <= max_width)
+  }
+}