Structured JSON Output (#8119)

integration-tests/json-output.test.ts

@@ -0,0 +1,37 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { expect, describe, it, beforeEach, afterEach } from 'vitest';
+import { TestRig } from './test-helper.js';
+
+describe('JSON output', () => {
+  let rig: TestRig;
+
+  beforeEach(async () => {
+    rig = new TestRig();
+    await rig.setup('json-output-test');
+  });
+
+  afterEach(async () => {
+    await rig.cleanup();
+  });
+
+  it('should return a valid JSON with response and stats', async () => {
+    const result = await rig.run(
+      'What is the capital of France?',
+      '--output-format',
+      'json',
+    );
+    const parsed = JSON.parse(result);
+
+    expect(parsed).toHaveProperty('response');
+    expect(typeof parsed.response).toBe('string');
+    expect(parsed.response.toLowerCase()).toContain('paris');
+
+    expect(parsed).toHaveProperty('stats');
+    expect(typeof parsed.stats).toBe('object');
+  });
+});

integration-tests/test-helper.ts

@@ -284,8 +284,15 @@ export class TestRig {
 
             result = filteredLines.join('\n');
           }
-          // If we have stderr output, include that also
-          if (stderr) {
+
+          // Check if this is a JSON output test - if so, don't include stderr
+          // as it would corrupt the JSON
+          const isJsonOutput =
+            commandArgs.includes('--output-format') &&
+            commandArgs.includes('json');
+
+          // If we have stderr output and it's not a JSON test, include that also
+          if (stderr && !isJsonOutput) {
             result += `\n\nStdErr:\n${stderr}`;
           }