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Load Testing With Playwright

Reuse Playwright end-to-end tests to generate k6 load tests for your Vaadin application.

This page covers the Playwright-specific aspects of load testing. For general load testing concepts, running tests, configuring think times, understanding k6 output, and more, see Load Testing. For an introduction to writing Playwright tests for Vaadin applications, see Testing with Playwright.

Overview

Unlike the TestBench path, which requires a BrowserMob Proxy to capture HTTP traffic, the Playwright path uses native HAR recording built into the browser. This results in fewer moving parts, and no proxy to run requests through.

The workflow is as follows:

  1. Write standard Playwright integration tests that simulate real user scenarios

  2. Record HTTP traffic automatically via Playwright’s native HAR capture

  3. Convert the captured HAR into Vaadin-aware k6 scripts

  4. Run the generated k6 scripts at scale against any target server

All steps after writing the tests are fully automated by the Maven plugin.

Playwright vs TestBench

Aspect Playwright TestBench

Recording method

Native HAR recording (built-in)

BrowserMob Proxy (MITM)

Proxy required

No

Yes

Maven goal

loadtest:record-playwright

loadtest:record

Prerequisites

The Playwright path requires the same base tools as the TestBench path (Java 21+, Maven 3.9+, k6), but does not require Chrome or ChromeDriver. Playwright downloads and manages its own browser binaries automatically.

Adapting Playwright Tests for Load Testing

Playwright tests for load testing are standard JUnit 5 integration tests — see Testing with Playwright for the basics of writing them. The only load-testing-specific requirement is using PlaywrightHelper.createBrowserContext(browser) to create the browser context. This enables transparent HAR recording when the test is run by the Maven plugin, and is a no-op during normal development runs.

Source code
Java
context = PlaywrightHelper.createBrowserContext(browser);  1
page = context.newPage();
page.navigate(PlaywrightHelper.getBaseUrl() + "/my-view");  2

  1. PlaywrightHelper.createBrowserContext() enables HAR recording when the k6.harOutputPath system property is set by the Maven plugin. When running tests normally (e.g., during development), it creates a plain browser context with no recording overhead.

  2. PlaywrightHelper.getBaseUrl() resolves the deployment URL from the HOSTNAME environment variable and server.port system property, defaulting to http://localhost:8080.

Best Practices for Load Test Scenarios

  • One scenario per test class — each test class maps to one k6 script. Keep scenarios focused on a single user journey.

  • Use semantic locators — prefer getByLabel(), getByRole(), and getByText() over CSS selectors. They are more resilient to UI changes.

  • Include assertions — assertions verify correctness during recording and serve as documentation. They don’t affect the generated k6 script.

  • Avoid destructive-only tests — if a test only deletes data, mark it with @Destructive so it can be skipped during recording runs. Prefer tests that create-then-delete.

  • Run headless during recording — use setHeadless(true) for CI and recording runs.

Project Setup

Application Module Dependencies

Add the testbench-loadtest-support and Playwright dependencies to your Vaadin application module:

Source code
XML
<dependency>
    <groupId>com.vaadin</groupId>
    <artifactId>testbench-loadtest-support</artifactId>
    <version>${vaadin.testbench.version}</version>
</dependency>

<dependency>
    <groupId>com.microsoft.playwright</groupId>
    <artifactId>playwright</artifactId>
    <version>1.58.0</version>
    <scope>test</scope>
</dependency>

Load Test Orchestration

Add a load test profile or create a separate Maven module (packaging pom) that orchestrates the recording and load test execution.

The key difference from the TestBench orchestration module is using the record-playwright goal instead of the record goal.

Source code
Minimal Load Test
<properties>
    <app.port>8081</app.port>
    <management.port>8082</management.port>
    <k6.vus>100</k6.vus>
    <k6.duration>30s</k6.duration>
    <k6.testDir>${project.build.directory}/k6/tests</k6.testDir>
</properties>

<build>
    <plugins>
        <!-- Load test plugin -->
        <plugin>
            <groupId>com.vaadin</groupId>
            <artifactId>testbench-converter-plugin</artifactId>
            <version>${vaadin.testbench.version}</version>
            <executions>
                <!-- 1. Start the application -->
                <execution>
                    <id>start-server</id>
                    <goals><goal>start-server</goal></goals>
                    <configuration>
                        <serverJar>${project.build.directory}/my-app.jar</serverJar>
                        <serverPort>${app.port}</serverPort>
                        <managementPort>${management.port}</managementPort>
                    </configuration>
                </execution>

                <!-- 2. Record Playwright scenarios -->
                <execution>
                    <id>record</id>
                    <phase>integration-test</phase>
                    <goals><goal>record-playwright</goal></goals>
                    <configuration>
                        <testClasses>
                            <testClass>MyScenarioPlaywrightIT</testClass>
                        </testClasses>
                        <appPort>${app.port}</appPort>
                        <testWorkDir>${project.basedir}</testWorkDir>
                        <harDir>${project.build.directory}</harDir>
                        <outputDir>${k6.testDir}</outputDir>
                    </configuration>
                </execution>

                <!-- 3. Run k6 load tests -->
                <execution>
                    <id>run</id>
                    <phase>integration-test</phase>
                    <goals><goal>run</goal></goals>
                    <configuration>
                        <testDir>${k6.testDir}</testDir>
                        <virtualUsers>${k6.vus}</virtualUsers>
                        <duration>${k6.duration}</duration>
                        <appPort>${app.port}</appPort>
                        <managementPort>${management.port}</managementPort>
                    </configuration>
                </execution>

                <!-- 4. Stop the application -->
                <execution>
                    <id>stop-server</id>
                    <goals><goal>stop-server</goal></goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

PlaywrightHelper API

The PlaywrightHelper class in testbench-loadtest-support provides two static methods:

createBrowserContext(Browser browser)

Creates a Playwright BrowserContext. When the k6.harOutputPath system property is set (automatically by the loadtest:record-playwright goal), HAR recording is enabled in FULL mode. Otherwise, a plain context is created.

getBaseUrl()

Returns the base URL of the application under test. Resolution order:

  1. HOSTNAME environment variable (if set) for the host, otherwise localhost

  2. server.port system property (if set) for the port, otherwise 8080

loadtest:record-playwright Goal

Records Playwright tests and converts captured HAR files to k6 scripts.

Parameter Type Default Description

testClasses

List<String>

required

Playwright test class names to record (without package prefix).

appPort

int

8080

Port where the application is running.

testWorkDir

String

required

Working directory of the application module (where mvn commands run for test execution).

harDir

String

target

Directory where HAR files are written.

outputDir

String

target/k6/tests

Directory where generated k6 scripts are placed.

skip

boolean

false

Skip recording.

For parameters related to running the generated k6 scripts (loadtest:run), configuring think times, combined scenarios, and understanding k6 output, see the main Load Testing documentation.

Troubleshooting

Playwright Test Fails During Recording

The test runs inside the application module’s Maven context. Ensure the application module builds successfully with mvn install before running the load test module.

HAR File is Empty or Missing

Verify that your test uses PlaywrightHelper.createBrowserContext(browser) and not browser.newContext() directly. The helper is what enables HAR recording.