diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 91667f49..3e5e451b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,7 +28,7 @@ jobs:
       - uses: DeterminateSystems/nix-installer-action@main
       - uses: DeterminateSystems/magic-nix-cache-action@main
       - run: echo "${GITHUB_WORKSPACE}" >> $GITHUB_PATH
-      - run: nix develop .#format -c poetry run isort --check-only ./tested ./tests
+      - run: nix develop .#format -c poetry run isort --check-only --diff ./tested ./tests
       - run: nix develop .#format -c poetry run black --check ./tested ./tests
   types:
     if: ${{ github.event.action != 'labeled' || (github.event.action == 'labeled' && github.event.label.name == 'run tests') }}
diff --git a/tests/test_functionality.py b/tests/test_functionality.py
index a0e98cd3..12cff032 100644
--- a/tests/test_functionality.py
+++ b/tests/test_functionality.py
@@ -16,7 +16,7 @@
 from tested.configs import create_bundle
 from tested.features import Construct
 from tested.judge.execution import ExecutionResult
-from tested.languages import get_language, LANGUAGES
+from tested.languages import LANGUAGES, get_language
 from tested.languages.generation import get_readable_input
 from tested.testsuite import Context, MainInput, Suite, Tab, Testcase, TextData
 from tests.language_markers import (
@@ -32,7 +32,10 @@ def test_global_variable(language: str, tmp_path: Path, pytestconfig: pytest.Con
     conf = configuration(
         pytestconfig, "global", language, tmp_path, "one.tson", "correct"
     )
-    if Construct.GLOBAL_VARIABLES not in get_language(None, conf.programming_language).supported_constructs():
+    if (
+        Construct.GLOBAL_VARIABLES
+        not in get_language(None, conf.programming_language).supported_constructs()
+    ):
         pytest.skip("Language doesn't support global variables")
     result = execute_config(conf)
     updates = assert_valid_output(result, pytestconfig)
@@ -46,7 +49,10 @@ def test_global_variable_yaml(
     conf = configuration(
         pytestconfig, "global", language, tmp_path, "plan.yaml", "correct"
     )
-    if Construct.GLOBAL_VARIABLES not in get_language(None, conf.programming_language).supported_constructs():
+    if (
+        Construct.GLOBAL_VARIABLES
+        not in get_language(None, conf.programming_language).supported_constructs()
+    ):
         pytest.skip("Language doesn't support global variables")
     result = execute_config(conf)
     updates = assert_valid_output(result, pytestconfig)