docs: catch up handoff and changelog

solitaire_engine/src/analytics_plugin.rs

@@ -204,3 +204,61 @@ fn mode_str(mode: GameMode) -> &'static str {
         GameMode::Difficulty(_) => "difficulty",
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use solitaire_core::game_state::DifficultyLevel;
+
+    use super::*;
+
+    #[test]
+    fn client_for_requires_analytics_opt_in() {
+        let settings = Settings {
+            analytics_enabled: false,
+            matomo_url: Some("https://analytics.example.com".into()),
+            ..Settings::default()
+        };
+
+        assert!(client_for(&settings).is_none());
+    }
+
+    #[test]
+    fn client_for_requires_matomo_url() {
+        let settings = Settings {
+            analytics_enabled: true,
+            matomo_url: None,
+            ..Settings::default()
+        };
+
+        assert!(client_for(&settings).is_none());
+    }
+
+    #[test]
+    fn client_for_creates_client_when_enabled_and_configured() {
+        let settings = Settings {
+            analytics_enabled: true,
+            matomo_url: Some("https://analytics.example.com".into()),
+            matomo_site_id: 2,
+            sync_backend: SyncBackend::SolitaireServer {
+                url: "https://solitaire.example.com".into(),
+                username: "alice".into(),
+                avatar_url: None,
+            },
+            ..Settings::default()
+        };
+
+        assert!(client_for(&settings).is_some());
+    }
+
+    #[test]
+    fn mode_labels_match_analytics_payload_contract() {
+        assert_eq!(mode_str(GameMode::Classic), "classic");
+        assert_eq!(mode_str(GameMode::Zen), "zen");
+        assert_eq!(mode_str(GameMode::Challenge), "challenge");
+        assert_eq!(mode_str(GameMode::TimeAttack), "time_attack");
+        assert_eq!(
+            mode_str(GameMode::Difficulty(DifficultyLevel::Grandmaster)),
+            "difficulty"
+        );
+    }
+}