diff --git a/Makefile b/Makefile
index 3b6c47f..b1b349b 100644
--- a/Makefile
+++ b/Makefile
@@ -4,13 +4,16 @@ test-requirements:
 test: test-lint test-unit test-types test-format ## Run all tests by decreasing order of priority
 
 test-format: ## Run code formatting tests
-	black --check --diff tests.py
+	black --check --diff *.py
 
 test-lint: ## Run code linting tests
-	pylint --errors-only --enable=unused-import,unused-argument --ignore=templates tests.py
+	pylint --errors-only --enable=unused-import,unused-argument --ignore=templates *.py
 
 test-unit: ## Run unit tests
 	python -m unittest run ./tests.py
 
 test-types: ## Check type definitions
-	mypy --ignore-missing-imports --implicit-reexport --strict tests.py
+	mypy --ignore-missing-imports --implicit-reexport --strict *.py
+
+format: ## Format code
+	black *.py
diff --git a/tests.py b/tests.py
index 178557b..7af95b2 100644
--- a/tests.py
+++ b/tests.py
@@ -30,14 +30,16 @@ def test_names_are_unique(self) -> None:
                     names.add(plugin["name"])
 
     def test_all_plugins_have_all_fields(self) -> None:
+        required_fields = ["src", "url", "author", "maintainer", "description"]
         for release in RELEASES:
             for index in INDEXES:
                 for plugin in load_index(release, index):
-                    self.assertIn("src", plugin)
-                    self.assertIn("url", plugin)
-                    self.assertIn("author", plugin)
-                    self.assertIn("maintainer", plugin)
-                    self.assertIn("description", plugin)
+                    for field in required_fields:
+                        self.assertIn(field, plugin)
+                        self.assertTrue(
+                            plugin[field] and plugin[field].strip(),
+                            f"Field {field} cannot be empty",
+                        )
 
 
 def load_index(release: str, index: str) -> list[dict[str, str]]: