chore: add tests for combining list styles (#1884)

Co-authored-by: Orhun Parmaksız <orhun@archlinux.org>

ratatui-widgets/src/list.rs

@@ -466,7 +466,11 @@ mod tests {
     use alloc::{format, vec};
 
     use pretty_assertions::assert_eq;
+    use ratatui_core::buffer::Buffer;
+    use ratatui_core::layout::Rect;
     use ratatui_core::style::{Color, Modifier, Stylize};
+    use ratatui_core::text::{Text, ToSpan};
+    use ratatui_core::widgets::StatefulWidget;
 
     use super::*;
 
@@ -493,4 +497,132 @@ mod tests {
                 .remove_modifier(Modifier::DIM)
         );
     }
+
+    #[test]
+    fn no_style() {
+        let text = Text::from("Item 1");
+        let list = List::new([ListItem::new(text)])
+            .highlight_symbol(">>")
+            .highlight_spacing(HighlightSpacing::Always);
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 1));
+
+        list.render(buffer.area, &mut buffer, &mut ListState::default());
+
+        assert_eq!(buffer, Buffer::with_lines(["  Item 1  "]));
+    }
+
+    #[test]
+    fn styled_text() {
+        let text = Text::from("Item 1").bold();
+        let list = List::new([ListItem::new(text)])
+            .highlight_symbol(">>")
+            .highlight_spacing(HighlightSpacing::Always);
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 1));
+
+        list.render(buffer.area, &mut buffer, &mut ListState::default());
+
+        assert_eq!(
+            buffer,
+            Buffer::with_lines([Line::from(vec!["  ".to_span(), "Item 1  ".bold(),])])
+        );
+    }
+
+    #[test]
+    fn styled_list_item() {
+        let text = Text::from("Item 1");
+        // note this avoids using the `Stylize' methods as that gets then combines the style
+        // instead of setting it directly (which is not the same for some implementations)
+        let item = ListItem::new(text).style(Modifier::ITALIC);
+        let list = List::new([item])
+            .highlight_symbol(">>")
+            .highlight_spacing(HighlightSpacing::Always);
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 1));
+
+        list.render(buffer.area, &mut buffer, &mut ListState::default());
+
+        assert_eq!(
+            buffer,
+            Buffer::with_lines([Line::from_iter(["  Item 1  ".italic()])])
+        );
+    }
+
+    #[test]
+    fn styled_text_and_list_item() {
+        let text = Text::from("Item 1").bold();
+        // note this avoids using the `Stylize' methods as that gets then combines the style
+        // instead of setting it directly (which is not the same for some implementations)
+        let item = ListItem::new(text).style(Modifier::ITALIC);
+        let list = List::new([item])
+            .highlight_symbol(">>")
+            .highlight_spacing(HighlightSpacing::Always);
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 1));
+
+        list.render(buffer.area, &mut buffer, &mut ListState::default());
+
+        assert_eq!(
+            buffer,
+            Buffer::with_lines([Line::from(vec!["  ".italic(), "Item 1  ".bold().italic()])])
+        );
+    }
+
+    #[test]
+    fn styled_highlight() {
+        let text = Text::from("Item 1").bold();
+        // note this avoids using the `Stylize' methods as that gets then combines the style
+        // instead of setting it directly (which is not the same for some implementations)
+        let item = ListItem::new(text).style(Modifier::ITALIC);
+        let mut state = ListState::default().with_selected(Some(0));
+        let list = List::new([item])
+            .highlight_symbol(">>")
+            .highlight_style(Color::Red);
+
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 1));
+        list.render(buffer.area, &mut buffer, &mut state);
+
+        assert_eq!(
+            buffer,
+            Buffer::with_lines([Line::from(vec![
+                ">>".italic().red(),
+                "Item 1  ".bold().italic().red(),
+            ])])
+        );
+    }
+
+    #[test]
+    fn style_inheritance() {
+        let bold = Modifier::BOLD;
+        let italic = Modifier::ITALIC;
+        let items = [
+            ListItem::new(Text::raw("Item 1")),               // no style
+            ListItem::new(Text::styled("Item 2", bold)),      // affects only the text
+            ListItem::new(Text::raw("Item 3")).style(italic), // affects the entire line
+            ListItem::new(Text::styled("Item 4", bold)).style(italic), // bold text, italic line
+            ListItem::new(Text::styled("Item 5", bold)).style(italic), // same but highlighted
+        ];
+        let mut state = ListState::default().with_selected(Some(4));
+        let list = List::new(items)
+            .highlight_symbol(">>")
+            .highlight_style(Color::Red)
+            .style(Style::new().on_blue());
+
+        let mut buffer = Buffer::empty(Rect::new(0, 0, 10, 5));
+        list.render(buffer.area, &mut buffer, &mut state);
+
+        assert_eq!(
+            buffer,
+            Buffer::with_lines(vec![
+                vec!["  Item 1  ".on_blue()],
+                vec!["  ".on_blue(), "Item 2  ".bold().on_blue()],
+                vec!["  Item 3  ".italic().on_blue()],
+                vec![
+                    "  ".italic().on_blue(),
+                    "Item 4  ".bold().italic().on_blue(),
+                ],
+                vec![
+                    ">>".italic().red().on_blue(),
+                    "Item 5  ".bold().italic().red().on_blue(),
+                ],
+            ])
+        );
+    }
 }