Add tests for not caching static files except fonts

tests/test_serve_static_files.py

@@ -0,0 +1,62 @@
+"""Test the code that mounts static files to the server, without creating a server."""
+
+import pytest
+from starlette.responses import FileResponse
+from openflexure_microscope_server.server import serve_static_files
+
+
+@pytest.fixture
+def mock_app(mocker):
+    """Return a mock FastAPI app.
+
+    This is just a mock, where the get method returns a mock.
+    """
+    wrapper = mocker.Mock()
+    app = mocker.Mock()
+    app.get.return_value = wrapper
+    return app
+
+
+@pytest.mark.parametrize(
+    "filename, allow_cache",
+    [
+        ["foo", False],
+        ["woff2.foo", False],
+        ["strange_file_ending_in_woff2", False],
+        ["fontfile.woff2", True],
+    ],
+)
+def test_add_static_file(filename, allow_cache, mock_app):
+    """Test running add_static_file with both font and non-font files.
+
+    This should creates a wrapped function that returns a FileResponse, this
+    should be have the path on disk and the no cache headers if not a woff2 font.
+    """
+    wrapper = mock_app.get.return_value
+    serve_static_files.add_static_file(mock_app, fname=filename, folder="bar")
+
+    # It is called once
+    assert mock_app.get.call_count == 1
+    # Check args for the get decorator
+    assert len(mock_app.get.call_args.args) == 1
+    assert mock_app.get.call_args.args[0] == "/" + filename
+    assert len(mock_app.get.call_args.kwargs) == 2
+    assert mock_app.get.call_args.kwargs["response_class"] == FileResponse
+    assert not mock_app.get.call_args.kwargs["include_in_schema"]
+
+    # Checked wrapper and the the returned wrapped function
+    assert wrapper.call_count == 1
+    wrapped = wrapper.call_args.args[0]
+    # the wrapped function should return the file response
+    response = wrapped()
+    assert isinstance(response, FileResponse)
+    assert response.path == "bar/" + filename
+    # The file response headers always have some standard data, and if the file is
+    # allowed to be cached it should also have the no_cache data
+    for key, value in serve_static_files.NO_CACHE_HEADERS.items():
+        if allow_cache:
+            assert key not in response.headers
+        else:
+            # Check headers that refuse caching are present
+            assert key in response.headers
+            assert response.headers[key] == value