rust_uprev: rewrite find_rust_versions() to use Path instead of os.*

This is a small refactor ahead of a change to the logic. The rewritten
find_rust_versions() returns a list of tuples of (RustVersion, Path)
instead of (RustVersion, str) as before, and updates the call sites
and test to match.

BUG=b:318424456
TEST=presubmit type checks and tests

Change-Id: If5e26ee3c40265031c43fe68d921d43405a44e3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/5233609
Reviewed-by: George Burgess <gbiv@chromium.org>
Commit-Queue: Bob Haarman <inglorion@chromium.org>
Tested-by: Bob Haarman <inglorion@chromium.org>

2 files changed, 21 insertions, 17 deletions

diff --git a/rust_tools/rust_uprev.py b/rust_tools/rust_uprev.py
index c0017186..bc64761c 100755
--- a/rust_tools/rust_uprev.py
+++ b/rust_tools/rust_uprev.py
@@ -401,13 +401,13 @@ def prepare_uprev(
         return None
 
     logging.info(
-        "Template Rust version is %s (ebuild: %r)",
+        "Template Rust version is %s (ebuild: %s)",
         template,
         ebuild_path,
     )
     logging.info("rust-bootstrap version is %s", bootstrap_version)
 
-    return PreparedUprev(template, Path(ebuild_path), bootstrap_version)
+    return PreparedUprev(template, ebuild_path, bootstrap_version)
 
 
 def create_ebuild(
@@ -933,11 +933,11 @@ def create_rust_uprev(
     )
 
 
-def find_rust_versions() -> List[Tuple[RustVersion, str]]:
+def find_rust_versions() -> List[Tuple[RustVersion, Path]]:
     return [
-        (RustVersion.parse_from_ebuild(x), os.path.join(RUST_PATH, x))
-        for x in os.listdir(RUST_PATH)
-        if x.endswith(".ebuild")
+        (RustVersion.parse_from_ebuild(ebuild), ebuild)
+        for ebuild in RUST_PATH.iterdir()
+        if ebuild.suffix == ".ebuild"
     ]
 
 
@@ -948,7 +948,7 @@ def find_oldest_rust_version() -> RustVersion:
     return min(rust_versions)[0]
 
 
-def find_ebuild_for_rust_version(version: RustVersion) -> str:
+def find_ebuild_for_rust_version(version: RustVersion) -> Path:
     rust_ebuilds = [
         ebuild for x, ebuild in find_rust_versions() if x == version
     ]
diff --git a/rust_tools/rust_uprev_test.py b/rust_tools/rust_uprev_test.py
index f93c18fd..1aca2839 100755
--- a/rust_tools/rust_uprev_test.py
+++ b/rust_tools/rust_uprev_test.py
@@ -467,7 +467,7 @@ class PrepareUprevTest(unittest.TestCase):
     @mock.patch.object(
         rust_uprev,
         "find_ebuild_for_rust_version",
-        return_value="/path/to/ebuild",
+        return_value=Path("/path/to/ebuild"),
     )
     @mock.patch.object(rust_uprev, "find_ebuild_path")
     @mock.patch.object(rust_uprev, "get_command_output")
@@ -858,21 +858,25 @@ class RustUprevOtherStagesTests(unittest.TestCase):
             ebuild_path.parent.joinpath(f"rust-{self.new_version}.ebuild"),
         )
 
-    @mock.patch.object(os, "listdir")
-    def test_find_oldest_rust_version_pass(self, mock_ls):
+    @mock.patch("rust_uprev.find_rust_versions")
+    def test_find_oldest_rust_version_pass(self, rust_versions):
         oldest_version_name = f"rust-{self.old_version}.ebuild"
-        mock_ls.return_value = [
-            oldest_version_name,
-            f"rust-{self.current_version}.ebuild",
-            f"rust-{self.new_version}.ebuild",
+        rust_versions.return_value = [
+            (self.old_version, oldest_version_name),
+            (self.current_version, f"rust-{self.current_version}.ebuild"),
+            (self.new_version, f"rust-{self.new_version}.ebuild"),
         ]
         actual = rust_uprev.find_oldest_rust_version()
         expected = self.old_version
         self.assertEqual(expected, actual)
 
-    @mock.patch.object(os, "listdir")
-    def test_find_oldest_rust_version_fail_with_only_one_ebuild(self, mock_ls):
-        mock_ls.return_value = [f"rust-{self.new_version}.ebuild"]
+    @mock.patch("rust_uprev.find_rust_versions")
+    def test_find_oldest_rust_version_fail_with_only_one_ebuild(
+        self, rust_versions
+    ):
+        rust_versions.return_value = [
+            (self.new_version, f"rust-{self.new_version}.ebuild"),
+        ]
         with self.assertRaises(RuntimeError) as context:
             rust_uprev.find_oldest_rust_version()
         self.assertEqual(