Test that all modules can be imported

Add an integration test that imports all modules to ensure
that all modules can be imported and that there are no
circular imports.

Signed-off-by: Daniel Zullo <[email protected]>

Author: daniel-zullo-frequenz

pyproject.toml

@@ -166,6 +166,9 @@ max-attributes = 12
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 required_plugins = ["pytest-asyncio", "pytest-mock"]
+markers = [
+  "integration: integration tests (deselect with '-m \"not integration\"')",
+]
 
 [tool.mypy]
 explicit_package_bases = true

tests/test_import_all_integration.py

@@ -0,0 +1,29 @@
+# License: MIT
+# Copyright © 2023 Frequenz Energy-as-a-Service GmbH
+
+"""Tests to verify that all modules can be imported successfully."""
+
+import importlib
+import os
+
+import pytest
+
+
+@pytest.mark.integration
+def test_all_modules_importable() -> None:
+    """Test that all modules can be imported.
+
+    This test is mainly to ensure that there are no circular imports.
+    """
+    src_path = "src"
+
+    for dir_path, _, files in os.walk(src_path):
+        for file in files:
+            if file.endswith(".py") and not file.startswith("__"):
+                module_path = os.path.join(dir_path, file)
+                module_name = os.path.splitext(module_path.replace(os.sep, "."))[0]
+
+                try:
+                    importlib.import_module(module_name)
+                except ImportError as error:
+                    assert False, f"Failed to import {module_name}: {error}"