ML-21: Classify API errors as transient vs permanent

test/wikipedia_test.exs

@@ -1,6 +1,8 @@
 defmodule WikipediaTest do
   use ExUnit.Case, async: true
 
+  alias Wikipedia.API.ErrorResponse
+
   describe "get_artist_summary/1" do
     test "resolves wikidata ID to Wikipedia summary with full intro" do
       wikidata_id = "Q352766"
@@ -38,5 +40,40 @@ defmodule WikipediaTest do
 
       assert {:error, :no_english_wikipedia} = Wikipedia.get_artist_summary(wikidata_id)
     end
+
+    @tag :capture_log
+    test "promotes HTTP 200 Action API error envelopes into ErrorResponse structs" do
+      wikidata_id = "Q352766"
+
+      Req.Test.stub(Wikipedia.API, fn conn ->
+        Req.Test.json(conn, %{
+          "error" => %{"code" => "ratelimited", "info" => "You've exceeded your rate limit."}
+        })
+      end)
+
+      assert {:error, %ErrorResponse{} = err} =
+               Wikipedia.get_artist_summary(wikidata_id)
+
+      assert err.status == 200
+      assert err.code == "ratelimited"
+      assert err.kind == :rate_limit
+      assert ErrorResponse.retryable?(err)
+    end
+
+    @tag :capture_log
+    test "classifies non-retryable Action API error codes as client errors" do
+      wikidata_id = "Q352766"
+
+      Req.Test.stub(Wikipedia.API, fn conn ->
+        Req.Test.json(conn, %{
+          "error" => %{"code" => "badtoken", "info" => "Invalid CSRF token."}
+        })
+      end)
+
+      assert {:error, %ErrorResponse{kind: :client_error} = err} =
+               Wikipedia.get_artist_summary(wikidata_id)
+
+      refute ErrorResponse.retryable?(err)
+    end
   end
 end