FullRepoManager cache property (Instagram#330)

Add public cache property to FullRepoManager

libcst/metadata/full_repo_manager.py

@@ -40,6 +40,16 @@ def __init__(
         self._providers = providers
         self._paths: List[str] = list(paths)
 
+    @property
+    def cache(self) -> Dict["ProviderT", Mapping[str, object]]:
+        """
+        The full repository cache data for all metadata providers passed in the ``providers`` parameter when
+        constructing :class:`~libcst.metadata.FullRepoManager`. Each provider is mapped to a mapping of path to cache.
+        """
+        # Make sure that the cache is available to us. If resolve_cache() was called manually then this is a noop.
+        self.resolve_cache()
+        return self._cache
+
     def resolve_cache(self) -> None:
         """
         Resolve cache for all providers that require it. Normally this is called by

libcst/metadata/tests/test_full_repo_manager.py

@@ -48,3 +48,15 @@ def test_get_metadata_wrapper_with_invalid_path(self, gen_cache: Mock) -> None:
             "The path needs to be in paths parameter when constructing FullRepoManager for efficient batch processing.",
         ):
             manager.get_metadata_wrapper_for_path(path)
+
+    @patch.object(TypeInferenceProvider, "gen_cache")
+    def test_get_full_repo_cache(self, gen_cache: Mock) -> None:
+        path_prefix = "tests/pyre/simple_class"
+        path = f"{path_prefix}.py"
+        mock_cache = {
+            path: json.loads((Path(REPO_ROOT_DIR) / f"{path_prefix}.json").read_text())
+        }
+        gen_cache.return_value = mock_cache
+        manager = FullRepoManager(REPO_ROOT_DIR, path, [TypeInferenceProvider])
+        cache = manager.cache
+        self.assertEqual(cache, {TypeInferenceProvider: mock_cache})