pw_build: Implement __contains__() in RunfilesManager

Change-Id: I0ecec5da7bbc829bed4c5419d681a3be77a87bd1
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/307900
Commit-Queue: Armando Montanez <[email protected]>
Reviewed-by: Keir Mierle <[email protected]>
Pigweed-Auto-Submit: Armando Montanez <[email protected]>
Lint: Lint 🤖 <[email protected]>
Docs-Not-Needed: Armando Montanez <[email protected]>
Copybara-Verified: Copybara Prod <[email protected]>
Presubmit-Verified: CQ Bot Account <[email protected]>

Author: armandomontanez

pw_build/py/pw_build/runfiles_manager.py

@@ -273,6 +273,13 @@ def get(self, key: str) -> Path:
     def __getitem__(self, key):
         return self.get(key)
 
+    def __contains__(self, key: str) -> bool:
+        try:
+            self.get(key)
+        except FileNotFoundError:
+            return False
+        return True
+
     def _run_tool(
         self, tool: str, args, **kwargs
     ) -> subprocess.CompletedProcess:

pw_build/py/runfiles_manager_test.py

@@ -62,6 +62,14 @@ def test_runfiles_at_root(self):
         self.assertTrue(c.is_file())
         self.assertEqual(c.read_text(), "OK\n")
 
+    def test_contains(self):
+        self.r.add_bazel_file('b', 'pw_build.test_runfile')
+        self.r.add_bootstrapped_file(
+            'b', '${PW_ROOT}/pw_build/test_data/test_runfile.txt'
+        )
+        self.assertTrue('b' in self.r)
+        self.assertFalse('nonexistent' in self.r)
+
     def test_bazel_missing(self):
         self.r.add_bootstrapped_file(
             'b', '${PW_ROOT}/pw_build/test_data/test_runfile.txt'