Better test isolation for fallback and more tests

Author: julianstirling

tests/test_fallback.py

@@ -7,9 +7,13 @@
 
 import re
 
+import pytest
+import uvicorn
+
 from fastapi.testclient import TestClient
 import labthings_fastapi as lt
 from labthings_fastapi.server.fallback import app
+from labthings_fastapi.example_things import ThingThatCantStart
 
 CONFIG_DICT = {
     "things": {
@@ -22,6 +26,37 @@
 }
 
 
+@pytest.fixture(autouse=True)
+def reset_app_state():
+    """Reset the fallback app state before each fallback test."""
+    app.labthings_config = None
+    app.labthings_server = None
+    app.labthings_error = None
+    app.log_history = None
+
+
+def test_fallback_redirect():
+    """Test that the redirect works."""
+    with TestClient(app) as client:
+        response = client.get("/")
+        # No history as no redirect
+        assert len(response.history) == 0
+        html = response.text
+        # test that something when wrong is shown
+        assert "Something went wrong" in html
+
+        # Now try another url
+        response = client.get("/foo/bar")
+        # redirected so there is a history item showing a 307 Temporary Redirect code.
+        assert len(response.history) == 1
+        assert response.history[0].status_code == 307
+
+        # Redirects to error page.
+        html = response.text
+        # test that something when wrong is shown
+        assert "Something went wrong" in html
+
+
 def test_fallback_empty():
     with TestClient(app) as client:
         response = client.get("/")
@@ -90,3 +125,38 @@ def test_fallback_with_log():
         assert "No logging info available" not in html
         assert "<p>Logging info</p>" in html
         assert "Fake log content" in html
+
+
+def test_actual_server_fallback():
+    """Test that the the server configures its startup failure correctly.
+
+    This may want to become an integration test in the fullness of time. Though
+    the integration test may want to actually let the cli really serve up the
+    fallback.
+    """
+    # ThingThatCantStart has an error in __enter__
+    server = lt.ThingServer({"bad_thing": ThingThatCantStart})
+
+    # Starting the server is a SystemExit
+    with pytest.raises(SystemExit, match="3") as excinfo:
+        uvicorn.run(server.app, port=5000)
+    server_error = excinfo.value
+    assert server.startup_failure is not None
+    assert server.startup_failure["thing"] == "bad_thing"
+    thing_error = server.startup_failure["exception"]
+    assert isinstance(thing_error, RuntimeError)
+
+    app.labthings_server = server
+    app.labthings_error = server_error
+    with TestClient(app) as client:
+        response = client.get("/")
+        html = response.text
+        assert "Something went wrong" in html
+        # Shouldn't be displaying the meaningless SystemExit
+        assert "SystemExit" not in html
+
+        # The message from when the Thing errored should be displayed
+        assert str(thing_error) in html
+        # With the traceback
+        assert 'labthings_fastapi/example_things/__init__.py", line' in html
+        assert f'RuntimeError("{thing_error}")' in html