Playwright Go Invoker Sample

Set Up

Install Playwright in a specific directory:

cd /Users/code/development/
npm init playwright@latest
# Continue the instructions from the official docs, etc.

And run the included sample tests from this directory:

export PLAYWRIGHT_DIR=/Users/code/development/playwright/
cd src/playwright-go-invoker/
go run .

Configuration

The global configuration resides in playwright.config.js in the directory where Playwright was installed. Observe many (all?) configuration can be overriden via command line parameters.

By defult, the test files will be picked from the directory where Playwright was installed, e.g. /Users/code/development/playwright/tests, but this can be overriden by telling Playwright where the file tests reside. In the case of this Invoker, simply specify a file or a directory via TEST_DIR, e.g. export TEST_DIR=/Users/code/test-microservice.ts.

Details

We invoke npx directly, instruct it to use JSON reporting, which we directly capture, parse and interpret. See an alternative for a alternative. A file to unmarshal JSON is generated from the observed output, as the JSON Schema is not explicit (see https://github.com/microsoft/playwright/blob/main/packages/playwright/types/testReporter.d.ts for further digging). Alternatively, we could include a custom javascript reporter and define our own output.

We are invoking playwright from scratch everytime we call it, which could be alleviated if playwright could be used as a long running service instead (most of the load time seems to come from starting the headless chromium/firefox/webkit instances).

Finally, similarly to playwright-go, we could decide to add sugar so users do not have to manually install playwright themselves first.

Previous approach

It was considered using playwright-go directly, i.e.

	opts := &playwright.RunOptions{
		Stdout: os.Stdout,
		Stderr: os.Stderr,
	}
	driver, err := playwright.NewDriver(opts)
	if err != nil {
		logger.Println(fmt.Sprintf("Could not create playwright driver: %w", err))
		return
	}
	err = driver.Install()
	if err != nil {
		logger.Println(fmt.Sprintf("Could not install playwright: %v", err))
		return
	}
	c := driver.Command("test", "/Users/code/development/testbed/playwright-go-invoker/src/playwright-go-invoker/tests/")

	bytes, err := c.Output()
	if err != nil {
		logger.Println(fmt.Sprintf("Could not fetch output: %v", err))
		return
	}

	handleJsonInput(bytes)
}

However, this cannot work as the driver used by the playwright-go is a stripped down version of playwright itself, and hence we cannot run actual javascript or typescript tests againt it.