Fixes#8206.
Since #8206 is a long-awaited (~ 1 year old), popular (~ 45 reactions, frequently requested in community channels, etc.), this PR aims to unblock folks.
Notably, we do not innovate on the `webServer` API, despite knowing we're not in love with it. We'll save the innovation for either Plugins or a new `LaunchConfigs` option. (We haven't yet arrived at a Plugin API we like, and instead of launching a new option guessing what the "better" launchConfig API would be, let's wait and see how folks use this new Array-variant of `webServer` which—despite its name—can be used for non-Web Server launches!
A few changes:
- `Matchers<R, T>` now carries both return and argument type.
- Based on the argument type, we apply playwright-specific Page/Locator matchers.
- Return type is usually void, unless wrapped with `expect.resolves`,
`expect.rejects` or `expect.poll()`.
- To preserve compatibility with any extended types in the wild,
argument type is optional.
1. Fixtures defined in test.extend() can now have `{ option: true }` configuration that makes them overridable in the config. Options support all other properties of fixtures - value/function, scope, auto.
```
const test = base.extend<MyOptions>({
foo: ['default', { option: true }],
});
```
2. test.declare() and project.define are removed.
3. project.use applies overrides to default option values and nothing else. Any test.extend() and test.use() calls take priority over config options.
Required user changes: if someone used to define fixture options with test.extend(), overriding them in config will stop working. The solution is to add `{ option: true }`.
```
// Old code
export const test = base.extend<{ myOption: number, myFixture: number }>({
myOption: 123,
myFixture: ({ myOption }, use) => use(2 * myOption),
});
// New code
export const test = base.extend<{ myOption: number, myFixture: number }>({
myOption: [123, { option: true }],
myFixture: ({ myOption }, use) => use(2 * myOption),
});
```
