feat(trace): allow saving trajectory as trace (#426)

tests/trace.spec.ts

@@ -0,0 +1,34 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * 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 fs from 'fs';
+import path from 'path';
+
+import { test, expect } from './fixtures.js';
+
+test('check that trace is saved', async ({ startClient, server, localOutputPath }) => {
+  const outputDir = localOutputPath('output');
+  const client = await startClient({
+    args: ['--save-trace', `--output-dir=${outputDir}`],
+  });
+
+  expect(await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  })).toContainTextContent(`Navigate to http://localhost`);
+
+  expect(fs.existsSync(path.join(outputDir, 'traces', 'trace.trace'))).toBeTruthy();
+});