feat: add editor component

crates/editor/tests/code_view.rs

@@ -0,0 +1,147 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use gpui::{
+    AppContext as _, Context, Entity, IntoElement, ParentElement as _, Render, Styled as _,
+    TestAppContext, VisualTestContext, Window, div,
+};
+use gpui_native_editor::code_view::CodeViewState;
+use gpui_native_editor::highlight::{HighlightedCode, Language, Role, highlight};
+
+fn spans_with_role(code: &HighlightedCode, role: Role) -> Vec<&str> {
+    code.lines
+        .iter()
+        .flat_map(|line| line.spans.iter())
+        .filter(|span| span.role == role)
+        .map(|span| span.text.as_ref())
+        .collect()
+}
+
+#[test]
+fn a_rust_snippet_gets_its_roles_from_the_grammar() {
+    let source = "// a comment\nfn main() {\n    let greeting = \"hello\";\n}\n";
+    let code = highlight(source, Language::Rust);
+
+    assert_eq!(code.lines.len(), 5, "a trailing newline ends an empty line");
+    assert!(spans_with_role(&code, Role::Comment).contains(&"// a comment"));
+    assert!(
+        spans_with_role(&code, Role::Keyword)
+            .iter()
+            .any(|text| text.contains("fn"))
+    );
+    assert!(
+        spans_with_role(&code, Role::Keyword)
+            .iter()
+            .any(|text| text.contains("let"))
+    );
+    assert!(spans_with_role(&code, Role::Function).contains(&"main"));
+    assert!(
+        spans_with_role(&code, Role::String)
+            .iter()
+            .any(|text| text.contains("hello"))
+    );
+}
+
+#[test]
+fn a_capture_spanning_newlines_styles_both_lines() {
+    let source = "let text = \"a\nb\";\n";
+    let code = highlight(source, Language::Rust);
+
+    assert!(
+        code.lines[0]
+            .spans
+            .iter()
+            .any(|span| span.role == Role::String && span.text.contains("\"a")),
+        "the string opens on the first line"
+    );
+    assert!(
+        code.lines[1]
+            .spans
+            .iter()
+            .any(|span| span.role == Role::String && span.text.contains("b\"")),
+        "and continues on the second"
+    );
+}
+
+#[test]
+fn set_source_rehighlights_with_the_new_language() {
+    let mut cx = TestAppContext::single();
+    let state = cx.new(|_| CodeViewState::new("test-code", "fn main() {}\n", Language::Rust));
+
+    cx.update(|cx| {
+        state.update(cx, |state, cx| {
+            state.set_source("def main():\n    pass\n", Language::Python, cx);
+        });
+    });
+
+    let code = cx.update(|cx| state.read(cx).code().clone());
+    assert!(
+        spans_with_role(&code, Role::Keyword)
+            .iter()
+            .any(|text| text.contains("def")),
+        "python's def highlights as a keyword"
+    );
+    assert!(spans_with_role(&code, Role::Function).contains(&"main"));
+}
+
+struct Host {
+    code: Entity<CodeViewState>,
+}
+
+impl Render for Host {
+    fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
+        div().size_full().child(self.code.clone())
+    }
+}
+
+fn code_view_window(
+    line_count: usize,
+) -> (TestAppContext, VisualTestContext, Entity<CodeViewState>) {
+    let mut cx = TestAppContext::single();
+    cx.update(gpui_native_theme::Theme::init);
+    let source: String = (0..line_count)
+        .map(|line| format!("fn line_{line}() {{}}\n"))
+        .collect();
+    let state = CodeViewState::new("test-code", source, Language::Rust);
+    let state_cell: Rc<RefCell<Option<Entity<CodeViewState>>>> = Rc::new(RefCell::new(None));
+    let cell = state_cell.clone();
+    let window = cx.add_window(move |_, cx| {
+        let code = cx.new(|_| state);
+        cell.borrow_mut().replace(code.clone());
+        Host { code }
+    });
+    let state = state_cell.borrow().clone().expect("state captured");
+    let mut visual = VisualTestContext::from_window(window.into(), &cx);
+    visual.update(|window, cx| {
+        window.draw(cx).clear(cx);
+    });
+    (cx, visual, state)
+}
+
+#[test]
+fn rows_render_virtualized_and_scroll() {
+    let (_cx, mut visual, state) = code_view_window(80);
+
+    assert!(
+        visual.debug_bounds("test-code-row-0").is_some(),
+        "the first row renders"
+    );
+    assert!(
+        visual.debug_bounds("test-code-row-79").is_none(),
+        "rows past the viewport never render"
+    );
+
+    state.update_in(&mut visual, |state, _window, _cx| state.scroll_to_line(79));
+    visual.update(|window, cx| {
+        window.draw(cx).clear(cx);
+    });
+
+    assert!(
+        visual.debug_bounds("test-code-row-79").is_some(),
+        "scrolling brings the last row in"
+    );
+    assert!(
+        visual.debug_bounds("test-code-row-0").is_none(),
+        "the first row scrolled out"
+    );
+}