playwright-test-coverage-native

playwright-test-coverage-native

Measure test coverage with Playwright. Its only dependency is @playwright/test — unlike its alternatives, playwright-test-coverage-native uses Playwright's built-in coverage functionality without Istanbul.

Installation

Using NPM:

npm i -D playwright-test-coverage-native

Using PNPM:

pnpm i -D playwright-test-coverage-native

Configuration

Add coverageDir to playwright.config.ts to set where coverage data should be written to. For example,

import { defineConfig, devices } from "playwright-test-coverage-native";

// See https://playwright.dev/docs/test-configuration.
export default defineConfig({
  projects: [
    {
      name: "chromium",
      use: {
        ...devices["Desktop Chrome"],
        coverageDir: './coverage/tmp',  // output location for coverage data
        coverageSrc: './src',           // filter coverage data for only files in ./src (optional)
        // one of: '@fs', 'localhosturl'. Sadly you'll just have to play around to see which one works
        coverageSourceMapHandler: '@fs'
      },
    },
  ],
});

[!NOTE]
Coverage APIs are only supported on Chromium-based browsers.

Usage

playwright-test-coverage-native is a drop-in replacement for @playwright/test. Edit the import of your test files like this:

-import { test, expect } from '@playwright/test';
+import { test, expect } from 'playwright-test-coverage-native';

If you're brave, you can do the changes in bulk:

# using GNU coreutils
find -type f -name '*.test.?s' -exec sed -i -e 's#@playwright/test#playwright-test-coverage-native#' \;

Post-processing

Install c8.

After running playwright test -c playwright.config.ts, run c8 report to print a summary of the coverage. c8 report is also used to convert to various formats, see c8 report --help for more options.

Alternatives

[!NOTE]
V8 code coverage can be inaccurate due to JavaScript code transformation and source maps, in which case alternatives (which use istanbul) may be preferable.

• https://github.com/anishkny/playwright-test-coverage (requires babel-plugin-istanbul instrumentation)
• https://github.com/mxschmitt/playwright-test-coverage (requires vite-plugin-istanbul)