Fixes TypeInferenceProvider breakage with empty cache. (#476)

* Fixes TypeInferenceProvider breakage with empty cache.
Instagram · Apr 8, 2021 · 068b905 · 068b905
1 parent e759ca8
commit 068b905
Show file tree

Hide file tree

Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/libcst/metadata/tests/test_type_inference_provider.py b/libcst/metadata/tests/test_type_inference_provider.py
@@ -66,3 +66,10 @@ def test_simple_class_types(self, source_path: Path, data_path: Path) -> None:
             cache={TypeInferenceProvider: data},
         )
         _test_simple_class_helper(self, wrapper)
+
+    def test_with_empty_cache(self) -> None:
+        tip = TypeInferenceProvider({})
+        self.assertEqual(tip.lookup, {})
+
+        tip = TypeInferenceProvider(PyreData())
+        self.assertEqual(tip.lookup, {})
diff --git a/libcst/metadata/type_inference_provider.py b/libcst/metadata/type_inference_provider.py
@@ -32,7 +32,7 @@ class InferredType(TypedDict):
     annotation: str
 
 
-class PyreData(TypedDict):
+class PyreData(TypedDict, total=False):
     types: Sequence[InferredType]
 
 
@@ -75,7 +75,8 @@ def gen_cache(
     def __init__(self, cache: PyreData) -> None:
         super().__init__(cache)
         lookup: Dict[CodeRange, str] = {}
-        for item in cache["types"]:
+        cache_types = cache.get("types", [])
+        for item in cache_types:
             location = item["location"]
             start = location["start"]
             end = location["stop"]