Add unit tests for all of serving static files. Update docs in src to clarify behaviour

tests/test_serve_static_files.py

@@ -3,9 +3,10 @@
 import os
 import shutil
 import tempfile
+import asyncio
 
 import pytest
-from starlette.responses import FileResponse
+from starlette.responses import FileResponse, RedirectResponse
 
 from openflexure_microscope_server.server import serve_static_files
 
@@ -51,6 +52,7 @@ def test_add_static_file(filename, allow_cache, mock_app):
     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.
     """
+    # Get the wrapper function from the mocked decorator
     wrapper = mock_app.get.return_value
     serve_static_files.add_static_file(mock_app, fname=filename, folder="bar")
 
@@ -94,7 +96,7 @@ def test_add_static_with_no_static_dir(mock_app, mocker):
     assert mock_app.get.call_count == 0
 
 
-def test_check_static_dir(mocker, mock_static_dir):
+def test_check_static_dir(mock_static_dir, mocker):
     """Test check_static_dir recognises a basic webapp structure."""
     mocker.patch(
         "openflexure_microscope_server.server.serve_static_files.STATIC_PATH",
@@ -124,3 +126,59 @@ def test_check_static_dir(mocker, mock_static_dir):
     os.remove(index_path)
     with pytest.raises(FileNotFoundError):
         serve_static_files.check_static_dir()
+
+
+def test_add_static_files(mock_app, mock_static_dir, mocker):
+    """Check add_static_files mounts the internal webapp dirs, and sets endpoints for files."""
+    mocker.patch(
+        "openflexure_microscope_server.server.serve_static_files.STATIC_PATH",
+        mock_static_dir,
+    )
+    # Get the wrapper function from the mocked decorator
+    wrapper = mock_app.get.return_value
+    serve_static_files.add_static_files(mock_app, scans_folder=None)
+
+    # Get should have been called twice to create a route for index
+    assert mock_app.get.call_count == 2
+    # Once at root as a redirict
+    assert mock_app.get.call_args_list[0].args[0] == "/"
+    assert mock_app.get.call_args_list[0].kwargs["response_class"] == RedirectResponse
+    # Once at index.html as a file response
+    assert mock_app.get.call_args_list[1].args[0] == "/index.html"
+    assert mock_app.get.call_args_list[1].kwargs["response_class"] == FileResponse
+
+    # The wrapper was also called twice to wrap two different functions
+    assert wrapper.call_count == 2
+    first_wrapped = wrapper.call_args_list[0].args[0]
+    second_wrapped = wrapper.call_args_list[1].args[0]
+
+    # The first wrapped function is the redirect to "index.html", it is async
+    assert asyncio.run(first_wrapped()) == "/index.html"
+    # The second is the file response for index.html, the path should be to the file on
+    # disk
+    assert second_wrapped().path == os.path.join(mock_static_dir, "index.html")
+    # It shouldn't cache
+    assert second_wrapped().headers["Pragma"] == "no-cache"
+
+    # Also should have mounted both dirs
+    assert mock_app.mount.call_count == 2
+    mounted_paths = [call.args[0] for call in mock_app.mount.call_args_list]
+    mounted_dirs = [call.args[1].directory for call in mock_app.mount.call_args_list]
+    assert "/css/" in mounted_paths
+    assert "/js/" in mounted_paths
+    assert os.path.join(mock_static_dir, "css") in mounted_dirs
+    assert os.path.join(mock_static_dir, "js") in mounted_dirs
+
+
+def test_add_static_files_with_scan_dir(mock_app, mock_static_dir, mocker):
+    """Check the scan dir mounts if supplied."""
+    mocker.patch(
+        "openflexure_microscope_server.server.serve_static_files.STATIC_PATH",
+        mock_static_dir,
+    )
+    with tempfile.TemporaryDirectory() as scandir:
+        serve_static_files.add_static_files(mock_app, scans_folder=scandir)
+    # The scan dir should be the last to mount so can use call args. It should mount
+    # at /scans/
+    assert mock_app.mount.call_args.args[0] == "/scans/"
+    assert mock_app.mount.call_args.args[1].directory == scandir