doc(html): document html reporter (#9528)

docs/src/test-reporters-js.md

@@ -258,6 +258,54 @@ Running 124 tests using 6 workers
 ······F·············································
 ```
 
+### HTML reporter
+
+HTML reporter produces a self-contained folder that contains report for the test run that can be served as a web page.
+It is usually used together with some terminal reporter like `dot` or `line`.
+
+```bash
+npx playwright test --reporter=html,dot
+```
+
+By default, report is written into the `playwright-report` folder in the current working directory. One can override
+that location using the `PLAYWRIGHT_HTML_REPORT` environment variable or a reporter configuration.
+
+In configuration file, pass options directly:
+```js js-flavor=js
+// playwright.config.js
+// @ts-check
+
+/** @type {import('@playwright/test').PlaywrightTestConfig} */
+const config = {
+  reporter: [ ['html', { outputFolder: 'my-report' }] ],
+};
+
+module.exports = config;
+```
+
+```js js-flavor=ts
+// playwright.config.ts
+import { PlaywrightTestConfig } from '@playwright/test';
+
+const config: PlaywrightTestConfig = {
+  reporter: [ ['html', { outputFolder: 'my-report' }] ],
+};
+export default config;
+```
+
+A quick way of opening the last test run report is:
+
+```bash
+npx playwright show-report
+```
+
+Or if there is a custom folder name:
+
+```bash
+npx playwright show-report my-report
+```
+
+
 ### JSON reporter
 
 JSON reporter produces an object with all information about the test run. It is usually used together with some terminal reporter like `dot` or `line`.

packages/playwright-test/src/reporters/html.ts

@@ -102,6 +102,12 @@ export type TestStep = {
 class HtmlReporter {
   private config!: FullConfig;
   private suite!: Suite;
+  private _outputFolder: string | undefined;
+
+  constructor(options: { outputFolder?: string } = {}) {
+    // TODO: resolve relative to config.
+    this._outputFolder = options.outputFolder;
+  }
 
   onBegin(config: FullConfig, suite: Suite) {
     this.config = config;
@@ -115,7 +121,7 @@ class HtmlReporter {
       const report = rawReporter.generateProjectReport(this.config, suite);
       return report;
     });
-    const reportFolder = htmlReportFolder();
+    const reportFolder = htmlReportFolder(this._outputFolder);
     await removeFolders([reportFolder]);
     const builder = new HtmlBuilder(reportFolder, this.config.rootDir);
     const stats = builder.build(reports);
@@ -134,8 +140,12 @@ class HtmlReporter {
   }
 }
 
-export function htmlReportFolder(): string {
+export function htmlReportFolder(outputFolder?: string): string {
-  return path.resolve(process.cwd(), process.env[`PLAYWRIGHT_HTML_REPORT`] || 'playwright-report');
+  if (process.env[`PLAYWRIGHT_HTML_REPORT`])
+    return path.resolve(process.cwd(), process.env[`PLAYWRIGHT_HTML_REPORT`]);
+  if (outputFolder)
+    return outputFolder;
+  return path.resolve(process.cwd(), 'playwright-report');
 }
 
 export async function showHTMLReport(reportFolder: string | undefined) {