diff --git a/src/foo.py b/src/foo.py
index e69de29..4b825dc 100644
--- a/src/foo.py
+++ b/src/foo.py
@@ -0,0 +1,2 @@
+def foo() -> int:
+    return 1
diff --git a/tests/test_foo.py b/tests/test_foo.py
index e69de29..4b825dc 100644
--- a/tests/test_foo.py
+++ b/tests/test_foo.py
@@ -0,0 +1,2 @@
+def test_foo() -> None:
+    assert True
