test: intercept multipart request body (#14630)

tests/page/page-request-intercept.spec.ts

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import type { Route } from 'playwright-core';
+import type { Route, Request } from 'playwright-core';
 import { expect, test as base } from './pageTest';
 import fs from 'fs';
 import path from 'path';
@@ -174,3 +174,22 @@ it('should give access to the intercepted response body', async ({ page, server,
 
   await Promise.all([route.fulfill({ response }), evalPromise]);
 });
+
+it('should intercept multipart/form-data request body', async ({ page, server, asset, browserName }) => {
+  it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/14624' });
+  it.fail(browserName !== 'firefox');
+  await page.goto(server.PREFIX + '/input/fileupload.html');
+  const filePath = path.relative(process.cwd(), asset('file-to-upload.txt'));
+  await page.locator('input[type=file]').setInputFiles(filePath);
+  const requestPromise = new Promise<Request>(async fulfill => {
+    await page.route('**/upload', route => {
+      fulfill(route.request());
+    });
+  });
+  const [request] = await Promise.all([
+    requestPromise,
+    page.click('input[type=submit]', { noWaitAfter: true })
+  ]);
+  expect(request.method()).toBe('POST');
+  expect(request.postData()).toContain(fs.readFileSync(filePath, 'utf8'));
+});