test(FirebaseAI): Add unit tests for ExecutableCodePart and CodeExecutionResultPart in ModelContent

Add tests to verify ModelContent can be initialized with:
- ExecutableCodePart
- CodeExecutionResultPart
- Mixed parts including these types

These tests ensure the bug fix is protected against regression.

Author: 18-RAJAT

FirebaseAI/Tests/Unit/ModelContentTests.swift

@@ -0,0 +1,100 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+import XCTest
+
+@testable import FirebaseAILogic
+
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+final class ModelContentTests: XCTestCase {
+  // MARK: - ModelContent Initialization with Part Types
+
+  func testInitWithExecutableCodePart() {
+    let executableCodePart = ExecutableCodePart(language: .python, code: "print('hello')")
+
+    let content = ModelContent(role: "model", parts: [executableCodePart])
+
+    XCTAssertEqual(content.role, "model")
+    XCTAssertEqual(content.parts.count, 1)
+    guard let resultPart = content.parts.first as? ExecutableCodePart else {
+      XCTFail("Expected ExecutableCodePart")
+      return
+    }
+    XCTAssertEqual(resultPart.language, .python)
+    XCTAssertEqual(resultPart.code, "print('hello')")
+  }
+
+  func testInitWithCodeExecutionResultPart() {
+    let codeExecutionResultPart = CodeExecutionResultPart(outcome: .ok, output: "hello")
+
+    let content = ModelContent(role: "model", parts: [codeExecutionResultPart])
+
+    XCTAssertEqual(content.role, "model")
+    XCTAssertEqual(content.parts.count, 1)
+    guard let resultPart = content.parts.first as? CodeExecutionResultPart else {
+      XCTFail("Expected CodeExecutionResultPart")
+      return
+    }
+    XCTAssertEqual(resultPart.outcome, .ok)
+    XCTAssertEqual(resultPart.output, "hello")
+  }
+
+  func testInitWithMixedPartsIncludingExecutableCode() {
+    let textPart = TextPart("Here is some code:")
+    let executableCodePart = ExecutableCodePart(language: .python, code: "x = 1 + 2")
+    let codeExecutionResultPart = CodeExecutionResultPart(outcome: .ok, output: "3")
+
+    let content = ModelContent(
+      role: "model",
+      parts: [textPart, executableCodePart, codeExecutionResultPart]
+    )
+
+    XCTAssertEqual(content.role, "model")
+    XCTAssertEqual(content.parts.count, 3)
+
+    // Verify each part type
+    XCTAssertTrue(content.parts[0] is TextPart)
+    XCTAssertTrue(content.parts[1] is ExecutableCodePart)
+    XCTAssertTrue(content.parts[2] is CodeExecutionResultPart)
+  }
+
+  func testInitWithExecutableCodePartPreservesThoughtMetadata() {
+    // Test that thought-related metadata is preserved through the conversion
+    let executableCodePart = ExecutableCodePart(language: .python, code: "print('test')")
+
+    let content = ModelContent(role: "model", parts: [executableCodePart])
+
+    guard let resultPart = content.parts.first as? ExecutableCodePart else {
+      XCTFail("Expected ExecutableCodePart")
+      return
+    }
+    // Verify the part maintains its properties after round-trip
+    XCTAssertEqual(resultPart.language, executableCodePart.language)
+    XCTAssertEqual(resultPart.code, executableCodePart.code)
+  }
+
+  func testInitWithCodeExecutionResultPartWithDeadlockedOutcome() {
+    let codeExecutionResultPart = CodeExecutionResultPart(outcome: .deadlineExceeded, output: nil)
+
+    let content = ModelContent(role: "model", parts: [codeExecutionResultPart])
+
+    guard let resultPart = content.parts.first as? CodeExecutionResultPart else {
+      XCTFail("Expected CodeExecutionResultPart")
+      return
+    }
+    XCTAssertEqual(resultPart.outcome, .deadlineExceeded)
+    XCTAssertNil(resultPart.output)
+  }
+}