run-make-support: add shallow_find_directories helper

Author: jieyouxu

src/tools/run-make-support/src/fs.rs

@@ -238,9 +238,7 @@ pub fn set_permissions<P: AsRef<Path>>(path: P, perm: std::fs::Permissions) {
     ));
 }
 
-/// A function which prints all file names in the directory `dir` similarly to Unix's `ls`.
-/// Useful for debugging.
-/// Usage: `eprintln!("{:#?}", shallow_find_dir_entries(some_dir));`
+/// List directory entries immediately under the given `dir`.
 #[track_caller]
 pub fn shallow_find_dir_entries<P: AsRef<Path>>(dir: P) -> Vec<PathBuf> {
     let paths = read_dir(dir);

src/tools/run-make-support/src/lib.rs

@@ -94,8 +94,8 @@ pub use artifact_names::{
 
 /// Path-related helpers.
 pub use path_helpers::{
-    cwd, filename_contains, filename_not_in_denylist, has_extension, has_prefix, has_suffix,
-    not_contains, path, shallow_find_files, build_root, source_root,
+    build_root, cwd, filename_contains, filename_not_in_denylist, has_extension, has_prefix,
+    has_suffix, not_contains, path, shallow_find_directories, shallow_find_files, source_root,
 };
 
 /// Helpers for scoped test execution where certain properties are attempted to be maintained.

src/tools/run-make-support/src/path_helpers.rs

@@ -59,6 +59,25 @@ pub fn shallow_find_files<P: AsRef<Path>, F: Fn(&PathBuf) -> bool>(
     matching_files
 }
 
+/// Browse the directory `path` non-recursively and return all directories which respect the
+/// parameters outlined by `closure`.
+#[track_caller]
+pub fn shallow_find_directories<P: AsRef<Path>, F: Fn(&PathBuf) -> bool>(
+    path: P,
+    filter: F,
+) -> Vec<PathBuf> {
+    let mut matching_files = Vec::new();
+    for entry in rfs::read_dir(path) {
+        let entry = entry.expect("failed to read directory entry.");
+        let path = entry.path();
+
+        if path.is_dir() && filter(&path) {
+            matching_files.push(path);
+        }
+    }
+    matching_files
+}
+
 /// Returns true if the filename at `path` does not contain `expected`.
 pub fn not_contains<P: AsRef<Path>>(path: P, expected: &str) -> bool {
     !path.as_ref().file_name().is_some_and(|name| name.to_str().unwrap().contains(expected))