Add App Check Limited-Use mode integration tests

Author: andrewheard

FirebaseAI/Tests/TestApp/Tests/Integration/GenerateContentIntegrationTests.swift

@@ -51,7 +51,9 @@ struct GenerateContentIntegrationTests {
     (InstanceConfig.vertexAI_v1beta, ModelNames.gemini2FlashLite),
     (InstanceConfig.vertexAI_v1beta_global, ModelNames.gemini2FlashLite),
     (InstanceConfig.vertexAI_v1beta_staging, ModelNames.gemini2FlashLite),
+    (InstanceConfig.vertexAI_v1beta_global_appCheckLimitedUse, ModelNames.gemini2FlashLite),
     (InstanceConfig.googleAI_v1beta, ModelNames.gemini2FlashLite),
+    (InstanceConfig.googleAI_v1beta_appCheckLimitedUse, ModelNames.gemini2FlashLite),
     (InstanceConfig.googleAI_v1beta, ModelNames.gemma3_4B),
     (InstanceConfig.googleAI_v1beta_staging, ModelNames.gemini2FlashLite),
     (InstanceConfig.googleAI_v1beta_staging, ModelNames.gemma3_4B),
@@ -165,15 +167,16 @@ struct GenerateContentIntegrationTests {
       (.googleAI_v1beta_freeTier, ModelNames.gemini2_5_Flash, ThinkingConfig(
         thinkingBudget: 24576, includeThoughts: true
       )),
-      (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
-        thinkingBudget: 0
-      )),
-      (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
-        thinkingBudget: 24576
-      )),
-      (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
-        thinkingBudget: 24576, includeThoughts: true
-      )),
+      // Note: The following configs are commented out for easy one-off manual testing.
+      // (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
+      //   thinkingBudget: 0
+      // )),
+      // (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
+      //   thinkingBudget: 24576
+      // )),
+      // (.googleAI_v1beta_freeTier_bypassProxy, ModelNames.gemini2_5_Flash, ThinkingConfig(
+      //   thinkingBudget: 24576, includeThoughts: true
+      // )),
     ] as [(InstanceConfig, String, ThinkingConfig)]
   )
   func generateContentThinking(_ config: InstanceConfig, modelName: String,

FirebaseAI/Tests/TestApp/Tests/Utilities/InstanceConfig.swift

@@ -27,12 +27,20 @@ struct InstanceConfig: Equatable, Encodable {
     location: "global",
     apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1beta)
   )
+  static let vertexAI_v1beta_global_appCheckLimitedUse = InstanceConfig(
+    location: "global",
+    useLimitedUseAppCheckTokens: true,
+    apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyProd), version: .v1beta)
+  )
   static let vertexAI_v1beta_staging = InstanceConfig(
     apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseProxyStaging), version: .v1beta)
   )
   static let googleAI_v1beta = InstanceConfig(
     apiConfig: APIConfig(service: .googleAI(endpoint: .firebaseProxyProd), version: .v1beta)
   )
+  static let googleAI_v1beta_appCheckLimitedUse = InstanceConfig(
+    apiConfig: APIConfig(service: .googleAI(endpoint: .firebaseProxyProd), version: .v1beta)
+  )
   static let googleAI_v1beta_staging = InstanceConfig(
     apiConfig: APIConfig(service: .googleAI(endpoint: .firebaseProxyStaging), version: .v1beta)
   )
@@ -49,9 +57,11 @@ struct InstanceConfig: Equatable, Encodable {
     vertexAI_v1beta,
     vertexAI_v1beta_global,
     vertexAI_v1beta_staging,
+    vertexAI_v1beta_global_appCheckLimitedUse,
     googleAI_v1beta,
     googleAI_v1beta_staging,
     googleAI_v1beta_freeTier_bypassProxy,
+    googleAI_v1beta_appCheckLimitedUse,
   ]
 
   static let vertexAI_v1beta_appCheckNotConfigured = InstanceConfig(