[VertexAI] Add schema minItems/maxItems test (#14703)

Author: paulb777

FirebaseVertexAI/Tests/TestApp/Tests/Integration/GenerateContentIntegrationTests.swift

@@ -165,6 +165,31 @@ struct GenerateContentIntegrationTests {
     #endif // canImport(UIKit)
   }
 
+  @Test(arguments: InstanceConfig.allConfigsExceptDeveloperV1)
+  func generateContentSchemaItems(_ config: InstanceConfig) async throws {
+    let model = VertexAI.componentInstance(config).generativeModel(
+      modelName: ModelNames.gemini2FlashLite,
+      generationConfig: GenerationConfig(
+        responseMIMEType: "application/json",
+        responseSchema:
+        .array(
+          items: .string(description: "The name of the city"),
+          description: "A list of city names",
+          minItems: 3,
+          maxItems: 5
+        )
+      ),
+      safetySettings: safetySettings
+    )
+    let prompt = "What are the biggest cities in Canada?"
+    let response = try await model.generateContent(prompt)
+    let text = try #require(response.text).trimmingCharacters(in: .whitespacesAndNewlines)
+    let jsonData = try #require(text.data(using: .utf8))
+    let decodedJSON = try JSONDecoder().decode([String].self, from: jsonData)
+    #expect(decodedJSON.count >= 3, "Expected at least 3 cities, but got \(decodedJSON.count)")
+    #expect(decodedJSON.count <= 5, "Expected at most 5 cities, but got \(decodedJSON.count)")
+  }
+
   // MARK: Streaming Tests
 
   @Test(arguments: InstanceConfig.allConfigs)

FirebaseVertexAI/Tests/TestApp/Tests/Utilities/InstanceConfig.swift

@@ -53,6 +53,14 @@ struct InstanceConfig {
     developerV1BetaSpark,
   ]
 
+  static let allConfigsExceptDeveloperV1 = [
+    vertexV1,
+    vertexV1Staging,
+    vertexV1Beta,
+    vertexV1BetaStaging,
+    developerV1BetaSpark,
+  ]
+
   static let vertexV1AppCheckNotConfigured = InstanceConfig(
     appName: FirebaseAppNames.appCheckNotConfigured,
     apiConfig: APIConfig(service: .vertexAI(endpoint: .firebaseVertexAIProd), version: .v1)