go: Add ability to run testable examples (#39390)

See related discussion #39381.

<img width="724" height="488"
src="https://github.com/user-attachments/assets/4a69e13e-783f-45d7-99f4-e23c0415a781"
/>

Release Notes:

- Added ability to run Go Testable Examples

crates/languages/src/go.rs

@@ -635,6 +635,22 @@ impl ContextProvider for GoContextProvider {
                 cwd: package_cwd.clone(),
                 ..TaskTemplate::default()
             },
+            TaskTemplate {
+                label: format!(
+                    "go test {} -run {}",
+                    GO_PACKAGE_TASK_VARIABLE.template_value(),
+                    VariableName::Symbol.template_value(),
+                ),
+                command: "go".into(),
+                args: vec![
+                    "test".into(),
+                    "-run".into(),
+                    format!("\\^{}\\$", VariableName::Symbol.template_value(),),
+                ],
+                tags: vec!["go-example".to_owned()],
+                cwd: package_cwd.clone(),
+                ..TaskTemplate::default()
+            },
             TaskTemplate {
                 label: format!("go test {}", GO_PACKAGE_TASK_VARIABLE.template_value()),
                 command: "go".into(),
@@ -992,6 +1008,43 @@ mod tests {
         );
     }
 
+    #[gpui::test]
+    fn test_go_example_test_detection(cx: &mut TestAppContext) {
+        let language = language("go", tree_sitter_go::LANGUAGE.into());
+
+        let example_test = r#"
+        package main
+
+        import "fmt"
+
+        func Example() {
+            fmt.Println("Hello, world!")
+            // Output: Hello, world!
+        }
+        "#;
+
+        let buffer =
+            cx.new(|cx| crate::Buffer::local(example_test, cx).with_language(language.clone(), cx));
+        cx.executor().run_until_parked();
+
+        let runnables: Vec<_> = buffer.update(cx, |buffer, _| {
+            let snapshot = buffer.snapshot();
+            snapshot.runnable_ranges(0..example_test.len()).collect()
+        });
+
+        let tag_strings: Vec<String> = runnables
+            .iter()
+            .flat_map(|r| &r.runnable.tags)
+            .map(|tag| tag.0.to_string())
+            .collect();
+
+        assert!(
+            tag_strings.contains(&"go-example".to_string()),
+            "Should find go-example tag, found: {:?}",
+            tag_strings
+        );
+    }
+
     #[gpui::test]
     fn test_go_table_test_slice_detection(cx: &mut TestAppContext) {
         let language = language("go", tree_sitter_go::LANGUAGE.into());

crates/languages/src/go/runnables.scm

@@ -71,6 +71,15 @@
   (#set! tag go-subtest)
 )
 
+; Functions names start with `Example`
+(
+  (
+    (function_declaration name: (_) @run @_name
+      (#match? @_name "^Example.*"))
+  ) @_
+  (#set! tag go-example)
+)
+
 ; Functions names start with `Benchmark`
 (
   (