Rollup merge of rust-lang#146450 - lolbinarycat:bootstrap-test-js, r=jieyouxu

bootstrap: rustdoc-js tests can now be filtered by js files

Before, a command like `./x test tests/rustdoc-js/path-ordering.js` would succeed, but run no tests, since the names of the tests are based on the `.rs` file.  This is a bit confusing, as the `rustdoc-js-std` test suite only has `.js` files, and thus those are the files you filter on.  Now, `./x test tests/rustdoc-js/path-ordering.js` will be treated as an alias for `./x test tests/rustdoc-js/path-ordering.rs`.  This is fairly simple as each `rustdoc-js` test has 2 files, 1 js file and one rust file, each with an identical base filename, so all we need to do is swap the extension.

r? `@Kobzol`

Author: jhpratt

src/bootstrap/src/core/build_steps/test.rs

@@ -2086,11 +2086,25 @@ HELP: You can add it into `bootstrap.toml` in `rust.codegen-backends = [{name:?}
         }
 
         // Get paths from cmd args
-        let paths = match &builder.config.cmd {
+        let mut paths = match &builder.config.cmd {
             Subcommand::Test { .. } => &builder.config.paths[..],
             _ => &[],
         };
 
+        // in rustdoc-js mode, allow filters to be rs files or js files.
+        // use a late-initialized Vec to avoid cloning for other modes.
+        let mut paths_v;
+        if mode == "rustdoc-js" {
+            paths_v = paths.to_vec();
+            for p in &mut paths_v {
+                if let Some(ext) = p.extension()
+                    && ext == "js"
+                {
+                    p.set_extension("rs");
+                }
+            }
+            paths = &paths_v;
+        }
         // Get test-args by striping suite path
         let mut test_args: Vec<&str> = paths
             .iter()