test: cover compatibility complete branch returns

tests/test_validate_typecheck_diagnostics.py

@@ -117,6 +117,12 @@ class ValidateTypecheckDiagnosticsTests(unittest.TestCase):
             MODULE.EXPECTED,
         )
 
+    def test_includes_compatibility_branch_complete_function_return_fixture(self):
+        self.assertIn(
+            "tests/typecheck_function_compat_branch_complete_good.claro",
+            MODULE.EXPECTED_OK,
+        )
+
     def test_includes_empty_function_return_fixture(self):
         self.assertIn("tests/typecheck_function_empty_return_bad.claro", MODULE.EXPECTED)
 

tests/typecheck_function_compat_branch_complete_good.claro

@@ -0,0 +1,9 @@
+TEACH choose TAKES flag RETURNS NUMBER
+    IF flag
+        RETURN 1
+    ELSE
+        RETURN 2
+    END
+LEARNED
+
+CALL choose WITH YES