ML-193: add secondary parser, search, and API coverage tests

Add ~80 focused tests across 10 files covering:

- Record set search by name, description, contained record title, artist name
- Navigation events for records, artists, record sets, links, and view-all actions
- MusicBrainz.ReleaseGroup parser (artist credits, included RGs, release IDs, types)
- MusicBrainz.ReleaseSearchResult edge cases (missing RG, unknown formats)
- LastFm.Session XML edge cases (non-subscriber, missing nodes)
- MusicLibrary.HttpError default status-kind mapping
- Discogs.API.ErrorResponse fallback message and retry-delay behavior
- ArtistRefreshWikipediaData {:cancel, :no_english_wikipedia} worker path
- StatsComponents grouped on-this-day records and anniversary labels

test/music_brainz/release_group_test.exs

@@ -0,0 +1,220 @@
+defmodule MusicBrainz.ReleaseGroupTest do
+  use ExUnit.Case, async: true
+
+  alias MusicBrainz.ReleaseGroup
+
+  describe "parse_artist_credits/1" do
+    test "extracts artist credits with joinphrases" do
+      musicbrainz_data = %{
+        "artist-credit" => [
+          %{
+            "joinphrase" => " & ",
+            "artist" => %{
+              "id" => "mbid-1",
+              "name" => "Steven Wilson",
+              "sort-name" => "Wilson, Steven",
+              "disambiguation" => "English musician"
+            }
+          },
+          %{
+            "joinphrase" => "",
+            "artist" => %{
+              "id" => "mbid-2",
+              "name" => "Mikael Åkerfeldt",
+              "sort-name" => "Åkerfeldt, Mikael",
+              "disambiguation" => "Swedish musician"
+            }
+          }
+        ]
+      }
+
+      assert ReleaseGroup.parse_artist_credits(musicbrainz_data) == [
+               %{
+                 name: "Steven Wilson",
+                 musicbrainz_id: "mbid-1",
+                 sort_name: "Wilson, Steven",
+                 disambiguation: "English musician",
+                 joinphrase: " & "
+               },
+               %{
+                 name: "Mikael Åkerfeldt",
+                 musicbrainz_id: "mbid-2",
+                 sort_name: "Åkerfeldt, Mikael",
+                 disambiguation: "Swedish musician",
+                 joinphrase: ""
+               }
+             ]
+    end
+
+    test "returns empty list when artist-credit key is empty list" do
+      assert ReleaseGroup.parse_artist_credits(%{"artist-credit" => []}) == []
+    end
+
+    test "returns empty list when artist-credit has no artists" do
+      assert ReleaseGroup.parse_artist_credits(%{"artist-credit" => []}) == []
+    end
+  end
+
+  describe "included_release_groups/1" do
+    test "filters related release groups with correct target-type and direction" do
+      release_group = %{
+        "relations" => [
+          %{
+            "target-type" => "release_group",
+            "type" => "included in",
+            "direction" => "backward",
+            "release_group" => %{
+              "id" => "rg-included-1",
+              "primary-type" => "EP",
+              "title" => "Bonus Disc",
+              "artist-credit" => [
+                %{"artist" => %{"name" => "Test Artist"}, "joinphrase" => ""}
+              ],
+              "first-release-date" => "2020-01-01"
+            }
+          },
+          %{
+            "target-type" => "url",
+            "type" => "other databases",
+            "direction" => "forward",
+            "release_group" => nil
+          },
+          %{
+            "target-type" => "release_group",
+            "type" => "included in",
+            "direction" => "forward",
+            "release_group" => %{
+              "id" => "rg-forward",
+              "primary-type" => "Album",
+              "title" => "Forward RG",
+              "artist-credit" => [],
+              "first-release-date" => "2019-01-01"
+            }
+          }
+        ]
+      }
+
+      result = ReleaseGroup.included_release_groups(release_group)
+      assert length(result) == 1
+      assert hd(result).id == "rg-included-1"
+      assert hd(result).type == :ep
+    end
+
+    test "returns empty list when no relations key" do
+      assert ReleaseGroup.included_release_groups(%{}) == []
+    end
+
+    test "returns empty list when no matching relations" do
+      release_group = %{
+        "relations" => [
+          %{
+            "target-type" => "url",
+            "type" => "wikipedia",
+            "direction" => "forward"
+          }
+        ]
+      }
+
+      assert ReleaseGroup.included_release_groups(release_group) == []
+    end
+  end
+
+  describe "release_ids/1" do
+    test "extracts IDs from releases" do
+      release_group = %{
+        "releases" => [
+          %{"id" => "rel-1"},
+          %{"id" => "rel-2"},
+          %{"id" => "rel-3"}
+        ]
+      }
+
+      assert ReleaseGroup.release_ids(release_group) == ["rel-1", "rel-2", "rel-3"]
+    end
+
+    test "returns empty list when no releases" do
+      assert ReleaseGroup.release_ids(%{}) == []
+      assert ReleaseGroup.release_ids(%{"releases" => []}) == []
+    end
+  end
+
+  describe "included_release_group_ids/1" do
+    test "extracts IDs from included release groups" do
+      release_group = %{
+        "relations" => [
+          %{
+            "target-type" => "release_group",
+            "type" => "included in",
+            "direction" => "backward",
+            "release_group" => %{
+              "id" => "rg-sub-1",
+              "primary-type" => "EP",
+              "title" => "Bonus",
+              "artist-credit" => [],
+              "first-release-date" => "2020-01-01"
+            }
+          }
+        ]
+      }
+
+      assert ReleaseGroup.included_release_group_ids(release_group) == ["rg-sub-1"]
+    end
+  end
+
+  describe "parse_record_type/2" do
+    test "Album without special secondary types is :album" do
+      assert ReleaseGroup.parse_record_type("Album", ["Soundtrack"]) == :album
+    end
+
+    test "Album with Live secondary type is :live" do
+      assert ReleaseGroup.parse_record_type("Album", ["Live"]) == :live
+    end
+
+    test "Album with Compilation secondary type is :compilation" do
+      assert ReleaseGroup.parse_record_type("Album", ["Compilation"]) == :compilation
+    end
+
+    test "Live overrides Compilation when both are in secondary types" do
+      assert ReleaseGroup.parse_record_type("Album", ["Compilation", "Live"]) == :live
+    end
+
+    test "Album with nil secondary types defaults to :album" do
+      assert ReleaseGroup.parse_record_type("Album", nil) == :album
+    end
+
+    test "EP maps to :ep" do
+      assert ReleaseGroup.parse_record_type("EP", ["Live"]) == :ep
+    end
+
+    test "Single maps to :single" do
+      assert ReleaseGroup.parse_record_type("Single", nil) == :single
+    end
+
+    test "Unknown primary type maps to :other" do
+      assert ReleaseGroup.parse_record_type("Broadcast", nil) == :other
+      assert ReleaseGroup.parse_record_type(nil, nil) == :other
+    end
+  end
+
+  describe "parse_type/1" do
+    test "maps known types to atoms" do
+      assert ReleaseGroup.parse_type("Album") == :album
+      assert ReleaseGroup.parse_type("EP") == :ep
+      assert ReleaseGroup.parse_type("Live") == :live
+      assert ReleaseGroup.parse_type("Compilation") == :compilation
+      assert ReleaseGroup.parse_type("Single") == :single
+    end
+
+    test "maps unknown types to :other" do
+      assert ReleaseGroup.parse_type("Broadcast") == :other
+      assert ReleaseGroup.parse_type(nil) == :other
+      assert ReleaseGroup.parse_type("") == :other
+    end
+  end
+
+  describe "url/1" do
+    test "generates MusicBrainz URL" do
+      assert ReleaseGroup.url("mbid-123") == "https://musicbrainz.org/release-group/mbid-123"
+    end
+  end
+end