Jest compatibility API: mock.contexts is not supported #2810
Description
Clear and concise description of the problem
Jest added support for testing function context ("this") in Mock functions in jest@28.x
PR jestjs/jest#11235
Docs: https://jestjs.io/docs/mock-function-api#mockfnmockcontexts
It would be useful to have this in vitest too.
Suggested solution
mock.context is added in vitest, so that the following test code can be written
test("contexts", () => {
const mockFn = vi.fn();
expect(mockFn.mock.contexts).toHaveLength(0);
const bindContext = { x : 1 };
const boundMockFn = mockFn.bind(bindContext);
boundMockFn();
expect(mockFn.mock.contexts).toHaveLength(1);
expect(mockFn.mock.contexts[0]).toBe(bindContext);
const callContext = { x : 2 };
mockFn.call(callContext);
expect(mockFn.mock.contexts).toHaveLength(2);
expect(mockFn.mock.contexts[1]).toBe(callContext);
const applyContext = { x : 3 };
mockFn.apply(applyContext);
expect(mockFn.mock.contexts).toHaveLength(3);
expect(mockFn.mock.contexts[2]).toBe(applyContext);
})Alternative
Skip adding the support for context.
Additional context
This issue was noticed while adding support for transformation of jest to vi API in trivikr/vitest-codemod#80
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