feat: added chai style assertions #8842
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docs/api/expect.md
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| ## Chai-Style Spy Assertions |
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This is a guide, not an API.
For an API we need all methods to be described similar to other to* assertions
The current doc can be moved to guides
docs/guide/migration.md
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| ::: tip | ||
| Vitest supports both `before`/`after` (Mocha-style) and `beforeAll`/`afterAll` (Jest-style) - they're aliases! |
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Vitest does not support before/after
docs/guide/migration.md
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| ### Assertions | ||
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| Vitest includes Chai assertions by default, so most Chai assertions work without changes: |
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Let's remove the "most" part, all of them work the same way
docs/guide/migration.md
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| ``` | ||
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| ::: tip | ||
| Notice the only difference: Chai-style assertions in Vitest use method calls `called()` instead of properties `called`. This is because Vitest implements these as methods that delegate to Jest-style matchers. |
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I think we still want them to be defined in the same way that sinon-chai does:
expect(spy).to.have.been.called
expect(spy).to.have.been.calledOnce
expect(spy).to.have.been.calledWith('arg1', 'arg2')There was a problem hiding this comment.
Refactored to that format
docs/guide/migration.md
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| vi.useRealTimers() | ||
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| ### Async Testing |
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| // Chai-style assertion: called | ||
| // Delegates to: toHaveBeenCalled | ||
| def('called', 'toHaveBeenCalled') |
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| // Chai-style assertion: called |
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All of the comments can be removed, they do not provide any value
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| // Chai-style assertion: calledTwice | ||
| // Wrapper that calls toHaveBeenCalledTimes(2) | ||
| utils.addMethod( |
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Why can't we use def for this? Maybe enhance it to support a property with specified arguments
| * Chai-style equivalent of `toHaveBeenCalledTimes(2)`. | ||
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| * @example | ||
| * expect(spy).to.have.been.calledTwice |
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All the examples show it as a property...
packages/expect/src/types.ts
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| * Chai-style assertions for spy/mock testing. | ||
| * These provide sinon-chai compatible assertion names that delegate to Jest-style implementations. | ||
| */ | ||
| export interface ChaiStyleAssertion { |
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Let's name it something like ChaiMockAssertion or something
2 participants
Description
This PR adds Chai-style assertion names for spy matchers, enabling users migrating from Mocha+Chai+Sinon to use familiar assertion syntax without rewriting their tests.
Resolves #8819
Users migrating from Mocha/Chai/Sinon to Vitest currently need to rewrite all their spy assertions from Chai-style (e.g.,
expect(spy).to.have.been.called) to Jest-style (e.g.,expect(spy).toHaveBeenCalled()). This creates friction during migration and requires significant test refactoring.This implementation provides Chai-style assertion names that delegate to existing Jest-style implementations, allowing both styles to coexist.
Added the following assertions that delegate to existing Jest-style implementations:
Property Assertions (no parentheses):
called->toHaveBeenCalledcalledOnce->toHaveBeenCalledOncecalledTwice->toHaveBeenCalledTimes(2)calledThrice->toHaveBeenCalledTimes(3)returned->toHaveReturnedMethod Assertions (with parentheses):
callCount(n)->toHaveBeenCalledTimes(n)calledWith(...args)->toHaveBeenCalledWith(...args)calledOnceWith(...args)->toHaveBeenCalledExactlyOnceWith(...args)lastCalledWith(...args)->toHaveBeenLastCalledWith(...args)nthCalledWith(n, ...args)->toHaveBeenNthCalledWith(n, ...args)returnedWith(value)->toHaveReturnedWith(value)returnedTimes(n)->toHaveReturnedTimes(n)lastReturnedWith(value)->toHaveLastReturnedWith(value)nthReturnedWith(n, value)->toHaveNthReturnedWith(n, value)calledBefore(spy)->toHaveBeenCalledBefore(spy)calledAfter(spy)->toHaveBeenCalledAfter(spy)Tests
pnpm test:ci.Documentation