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Merged
SimenB merged 8 commits into from
Feb 2, 2023
Merged

feat(@jest/expect): Expose type of actual to Matchers #13848

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4bfbc6b
feat(@jest/expect): Expose type of actual to Matchers
benjaminjkraft Jan 31, 2023
b9c5c27
review comments
benjaminjkraft Feb 1, 2023
d6459b4
add PR number in changelog
benjaminjkraft Feb 1, 2023
2b7490e
changelog comments
benjaminjkraft Feb 1, 2023
2b4fa2d
Update CHANGELOG.md
benjaminjkraft Feb 1, 2023
fc53bed
better way to avoid unused variable errors
benjaminjkraft Feb 1, 2023
6230a94
review comments
benjaminjkraft Feb 1, 2023
12d3bcc
review comments, again
benjaminjkraft Feb 1, 2023
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -4,6 +4,8 @@

### Fixes

- `[@jest/expect]` provide type of `actual` as a generic argument to `Matchers` to allow better-typed extensions (#13848)

### Chore & Maintenance

- `[*]` make sure to exclude `.eslintcache` from published module ([#13832](https://github.com/facebook/jest/pull/13832))
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1 change: 1 addition & 0 deletions packages/expect/__typetests__/expect.test.ts
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Expand Up @@ -19,6 +19,7 @@ import {
import type * as jestMatcherUtils from 'jest-matcher-utils';

type M = Matchers<void>;
type N = Matchers<void, string>;

expectError(() => {
type E = Matchers;
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22 changes: 22 additions & 0 deletions packages/expect/__typetests__/expectTyped.test.ts
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@@ -0,0 +1,22 @@
/**
* Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/

import {expectAssignable, expectError, expectType} from 'tsd-lite';
import {Matchers, expect} from 'expect';

declare module 'expect' {
interface Matchers<R, T> {
toTypedEqual(expected: T): void;
}
}

expectType<void>(expect(100).toTypedEqual(100));
expectType<void>(expect(101).not.toTypedEqual(101));

expectError(() => {
expect(100).toTypedEqual('three');
});
16 changes: 9 additions & 7 deletions packages/expect/src/types.ts
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Expand Up @@ -97,9 +97,9 @@ export interface BaseExpect {
}

export type Expect = {
<T = unknown>(actual: T): Matchers<void> &
Inverse<Matchers<void>> &
PromiseMatchers;
<T = unknown>(actual: T): Matchers<void, T> &
Inverse<Matchers<void, T>> &
PromiseMatchers<T>;
} & BaseExpect &
AsymmetricMatchers &
Inverse<Omit<AsymmetricMatchers, 'any' | 'anything'>>;
Expand All @@ -121,20 +121,22 @@ export interface AsymmetricMatchers {
stringMatching(sample: string | RegExp): AsymmetricMatcher;
}

type PromiseMatchers = {
type PromiseMatchers<T = unknown> = {
/**
* Unwraps the reason of a rejected promise so any other matcher can be chained.
* If the promise is fulfilled the assertion fails.
*/
rejects: Matchers<Promise<void>> & Inverse<Matchers<Promise<void>>>;
rejects: Matchers<Promise<void>, T> & Inverse<Matchers<Promise<void>, T>>;
/**
* Unwraps the value of a fulfilled promise so any other matcher can be chained.
* If the promise is rejected the assertion fails.
*/
resolves: Matchers<Promise<void>> & Inverse<Matchers<Promise<void>>>;
resolves: Matchers<Promise<void>, T> & Inverse<Matchers<Promise<void>, T>>;
};

export interface Matchers<R extends void | Promise<void>> {
// @ts-expect-error unused variable T (can't use _T since users redeclare Matchers)
// eslint-disable-next-line @typescript-eslint/no-unused-vars
export interface Matchers<R extends void | Promise<void>, T = unknown> {
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@mrazauskas mrazauskas Feb 1, 2023

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What about this:

Suggested change
// @ts-expect-error unused variable T (can't use _T since users redeclare Matchers)
// eslint-disable-next-line @typescript-eslint/no-unused-vars
export interface Matchers<R extends void | Promise<void>, T = unknown> {
export interface Matchers<R extends void | Promise<void>, T = unknown> {
/** @internal */
_doKeepT(expect: T): R;

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@mrazauskas mrazauskas Feb 1, 2023 •
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Could have some longer comment, but seems to be working. Or?

stripInternal documentation: https://www.typescriptlang.org/tsconfig#stripInternal

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@benjaminjkraft benjaminjkraft Feb 1, 2023

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Ah, great! I thought of adding a fake method but didn't realize I could hide it like that.

/**
* Ensures the last call to a mock function was provided specific args.
*/
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13 changes: 13 additions & 0 deletions packages/jest-expect/__typetests__/jest-expect.test.ts
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Expand Up @@ -29,3 +29,16 @@ expectError(() => {

expectAssignable<typeof expect>(jestExpect);
expectNotAssignable<typeof jestExpect>(expect);

declare module 'expect' {
interface Matchers<R, T> {
toTypedEqual(expected: T): void;
}
}

expectType<void>(jestExpect(100).toTypedEqual(100));
expectType<void>(jestExpect(101).not.toTypedEqual(101));

expectError(() => {
jestExpect(100).toTypedEqual('three');
});
2 changes: 1 addition & 1 deletion packages/jest-expect/src/types.ts
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Expand Up @@ -29,7 +29,7 @@ type Inverse<Matchers> = {
not: Matchers;
};

type JestMatchers<R extends void | Promise<void>, T> = Matchers<R> &
type JestMatchers<R extends void | Promise<void>, T> = Matchers<R, T> &
SnapshotMatchers<R, T>;

type PromiseMatchers<T = unknown> = {
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