Handle Wikipedia category API failures

tests/test_category_search.py

@@ -0,0 +1,85 @@
+"""Tests for Wikipedia category searches."""
+
+from unittest.mock import patch
+
+import requests
+
+from main import CategoryResult, app, get_articles_without_images
+
+
+def test_api_failure_is_not_reported_as_an_empty_success():
+    with patch("main.requests.get", side_effect=requests.ConnectionError("offline")):
+        result = get_articles_without_images("Category:Example")
+
+    assert result.articles == []
+    assert result.error == "Unable to load articles from Wikipedia. Please try again."
+
+
+def test_api_error_response_is_not_reported_as_an_empty_success():
+    error_response = type(
+        "Response",
+        (),
+        {
+            "raise_for_status": lambda self: None,
+            "json": lambda self: {
+                "error": {"code": "readonly", "info": "Wikipedia is read-only"}
+            },
+        },
+    )()
+
+    with patch("main.requests.get", return_value=error_response):
+        result = get_articles_without_images("Category:Example")
+
+    assert result.articles == []
+    assert result.error == "Unable to load articles from Wikipedia. Please try again."
+
+
+def test_api_failure_after_results_marks_them_as_partial():
+    first_response = type(
+        "Response",
+        (),
+        {
+            "raise_for_status": lambda self: None,
+            "json": lambda self: {
+                "query": {
+                    "pages": {
+                        "1": {"pageid": 1, "title": "No image", "images": []}
+                    }
+                },
+                "continue": {
+                    "gcmcontinue": "next-page",
+                    "continue": "gcmcontinue||",
+                },
+            },
+        },
+    )()
+
+    with patch(
+        "main.requests.get",
+        side_effect=[first_response, requests.ConnectionError("offline")],
+    ):
+        result = get_articles_without_images("Category:Example")
+
+    assert [article.title for article in result.articles] == ["No image"]
+    assert result.error is not None
+    assert "partial results" in result.error
+
+
+def test_category_page_does_not_claim_success_after_api_failure():
+    result = CategoryResult(
+        articles=[],
+        gcmcontinue=None,
+        error="Unable to load articles from Wikipedia. Please try again.",
+    )
+
+    with (
+        patch("main.get_articles_without_images", return_value=result),
+        patch("main.log_interaction"),
+        app.test_client() as client,
+    ):
+        response = client.get("/category?cat=Category:Example")
+
+    page = response.get_data(as_text=True)
+    assert response.status_code == 200
+    assert "Unable to load articles from Wikipedia" in page
+    assert "All articles in this category have images" not in page