[red-knot] Improve mdtest output (astral-sh#14213)

crates/red_knot_python_semantic/tests/mdtest.rs

@@ -1,24 +1,25 @@
-use dir_test::{dir_test, Fixture};
-use red_knot_test::run;
+use std::ffi::OsStr;
 use std::path::Path;
 
+use dir_test::{dir_test, Fixture};
+
 /// See `crates/red_knot_test/README.md` for documentation on these tests.
 #[dir_test(
     dir: "$CARGO_MANIFEST_DIR/resources/mdtest",
     glob: "**/*.md"
 )]
 #[allow(clippy::needless_pass_by_value)]
 fn mdtest(fixture: Fixture<&str>) {
-    let path = fixture.path();
+    let fixture_path = Path::new(fixture.path());
+    let crate_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let workspace_root = crate_dir.parent().and_then(Path::parent).unwrap();
 
-    let crate_dir = Path::new(env!("CARGO_MANIFEST_DIR"))
-        .join("resources/mdtest")
-        .canonicalize()
+    let long_title = fixture_path
+        .strip_prefix(workspace_root)
+        .unwrap()
+        .to_str()
         .unwrap();
+    let short_title = fixture_path.file_name().and_then(OsStr::to_str).unwrap();
 
-    let relative_path = path
-        .strip_prefix(crate_dir.to_str().unwrap())
-        .unwrap_or(path);
-
-    run(Path::new(path), relative_path);
+    red_knot_test::run(fixture_path, long_title, short_title);
 }

crates/red_knot_test/src/lib.rs

@@ -19,9 +19,9 @@ mod parser;
 ///
 /// Panic on test failure, and print failure details.
 #[allow(clippy::print_stdout)]
-pub fn run(path: &Path, title: &str) {
+pub fn run(path: &Path, long_title: &str, short_title: &str) {
     let source = std::fs::read_to_string(path).unwrap();
-    let suite = match test_parser::parse(title, &source) {
+    let suite = match test_parser::parse(short_title, &source) {
         Ok(suite) => suite,
         Err(err) => {
             panic!("Error parsing `{}`: {err}", path.to_str().unwrap())
@@ -49,8 +49,8 @@ pub fn run(path: &Path, title: &str) {
                     for failure in failures {
                         let absolute_line_number =
                             backtick_line.checked_add(relative_line_number).unwrap();
-                        let line_info = format!("{title}:{absolute_line_number}").cyan();
-                        println!("    {line_info} {failure}");
+                        let line_info = format!("{long_title}:{absolute_line_number}").cyan();
+                        println!("  {line_info} {failure}");
                     }
                 }
             }