[Feature] Parametrization API for Playwright Test

Discussed in https://github.com/microsoft/playwright/discussions/10283

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^{Originally posted by andrejs-ps November 12, 2021} Currently, there is no API to parametrize individual tests.

To pass in a single parameter, one would use a for loop, as suggested in the documentation (https://playwright.dev/docs/test-parameterize)

const people = ['Alice', 'Bob'];
for (const name in people) {
  test(`testing with ${name}`, async () => {
    // ...
  });
}

For two parameters, one can iterate over keys and values of a map. This isn’t exactly a clean solution, but it gets harder for 3+ parameters

for (const [a, b, c] of [["a", 1, 2], ["b", 3, 4], ["c", 5, 6]]) {
    test(`testing with ${a}  ${b} ${c}`, async () => {
        console.log(a, b, c);
    });
}

I believe Playwright would benefit from a parametrization API, similar to Java’s TestNG or JUnit. Example from JUnit:

@ParameterizedTest
@CsvSource({"a,1", "b,2", "foo,3"})

Given that Playwright has:

test.use({ viewport: { width: 600, height: 900 } });

Playwright could have as below for a single test or a group of tests

test.parameters("a,1", "b,2", "foo,3"});

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[dgozman]

@xelact No workaround for now. I’d suggest a separate step before npm run test, something like npm run generate-tests.

[xelact]

One aspect that would super useful is if we could create the test(description, method) based on the result of a test.beforeAll(...) or even better of a globalSetup.ts script.

You can do this with globalSetup.ts - just write some data to a file in the globalSetup, and then read it in your test file.

// example.spec.ts

const testCases = require('./generated-by-global-setup.json');
for (const { title, url } of testCases) {
  test(title, async ({ page }) => {
    await page.goto(url);
    expect(await page.screenshot()).toMatchSnapshot('default.png');
  });
}

After this change #12018 in v1.19, it is no longer possible to dynamically create test cases based on some data written in the globalSetup.ts as the global setup runs after listing the test cases, is there any workaround?