fix: Support relative imports for submodules (GoogleCloudPlatform#169)

Author: di

src/functions_framework/_function_registry.py

@@ -62,7 +62,9 @@ def load_function_module(source):
     directory, filename = os.path.split(realpath)
     name, extension = os.path.splitext(filename)
     # 2. Create a new module
-    spec = importlib.util.spec_from_file_location(name, realpath)
+    spec = importlib.util.spec_from_file_location(
+        name, realpath, submodule_search_locations=[directory]
+    )
     source_module = importlib.util.module_from_spec(spec)
     # 3. Add the directory of the source to sys.path to allow the function to
     # load modules relative to its location

tests/test_functions.py

@@ -604,3 +604,14 @@ def tests_cloud_to_background_event_client_invalid_source(
     resp = background_event_client.post("/", headers=headers, json=tempfile_payload)
 
     assert resp.status_code == 500
+
+
+def test_relative_imports():
+    source = TEST_FUNCTIONS_DIR / "relative_imports" / "main.py"
+    target = "function"
+
+    client = create_app(target, source).test_client()
+
+    resp = client.get("/")
+    assert resp.status_code == 200
+    assert resp.data == b"success"

tests/test_functions/relative_imports/main.py

@@ -0,0 +1,22 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Function used in test for relative imports."""
+
+from .test import foo
+
+
+def function(request):
+    """Test HTTP function who returns a value from a relative import"""
+    return foo

tests/test_functions/relative_imports/test.py

@@ -0,0 +1 @@
+foo = "success"