feat(expect): replace RawMatcherFn with MatcherFunction and `Matc…

…herFunctionWithState` types (#12376)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[expect]` Expose `AsymmetricMatchers`, `MatcherFunction` and `MatcherFunctionWithState` interfaces ([#12363](https://github.com/facebook/jest/pull/12363), [#12376](https://github.com/facebook/jest/pull/12376))
 - `[jest-config]` [**BREAKING**] Stop shipping `jest-environment-jsdom` by default ([#12354](https://github.com/facebook/jest/pull/12354))
 - `[jest-config]` [**BREAKING**] Stop shipping `jest-jasmine2` by default ([#12355](https://github.com/facebook/jest/pull/12355))
 - `[jest-config, @jest/types]` Add `ci` to `GlobalConfig` ([#12378](https://github.com/facebook/jest/pull/12378))
@@ -16,7 +17,6 @@
 ### Fixes
 
 - `[expect]` Move typings of `.not`, `.rejects` and `.resolves` modifiers outside of `Matchers` interface ([#12346](https://github.com/facebook/jest/pull/12346))
-- `[expect]` Expose `AsymmetricMatchers` and `RawMatcherFn` interfaces ([#12363](https://github.com/facebook/jest/pull/12363))
 - `[jest-config]` Correctly detect CI environment and update snapshots accordingly ([#12378](https://github.com/facebook/jest/pull/12378))
 - `[jest-config]` Pass `moduleTypes` to `ts-node` to enforce CJS when transpiling ([#12397](https://github.com/facebook/jest/pull/12397))
 - `[jest-environment-jsdom]` Make `jsdom` accessible to extending environments again ([#12232](https://github.com/facebook/jest/pull/12232))

examples/expect-extend/toBeWithinRange.ts

@@ -6,13 +6,21 @@
  */
 
 import {expect} from '@jest/globals';
-import type {RawMatcherFn} from 'expect';
+import type {MatcherFunction} from 'expect';
 
-const toBeWithinRange: RawMatcherFn = (
-  actual: number,
-  floor: number,
-  ceiling: number,
+const toBeWithinRange: MatcherFunction<[floor: number, ceiling: number]> = (
+  actual: unknown,
+  floor: unknown,
+  ceiling: unknown,
 ) => {
+  if (
+    typeof actual !== 'number' ||
+    typeof floor !== 'number' ||
+    typeof ceiling !== 'number'
+  ) {
+    throw new Error('These must be of type number!');
+  }
+
   const pass = actual >= floor && actual <= ceiling;
   if (pass) {
     return {

packages/expect/__typetests__/expect.test.ts

@@ -5,9 +5,15 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {expectError, expectType} from 'tsd-lite';
+import {expectAssignable, expectError, expectType} from 'tsd-lite';
 import type {EqualsFunction, Tester} from '@jest/expect-utils';
-import {type Matchers, expect} from 'expect';
+import {
+  type MatcherFunction,
+  type MatcherFunctionWithState,
+  type MatcherState,
+  type Matchers,
+  expect,
+} from 'expect';
 import type * as jestMatcherUtils from 'jest-matcher-utils';
 
 type M = Matchers<void, unknown>;
@@ -24,6 +30,7 @@ type MatcherUtils = typeof jestMatcherUtils & {
   subsetEquality: Tester;
 };
 
+// TODO `actual` should be allowed to have only `unknown` type
 expectType<void>(
   expect.extend({
     toBeWithinRange(actual: number, floor: number, ceiling: number) {
@@ -79,3 +86,128 @@ expectType<void>(
     bananas: expect.not.toBeWithinRange(11, 20),
   }),
 );
+
+// MatcherFunction
+
+expectError(() => {
+  const actualMustBeUnknown: MatcherFunction = (actual: string) => {
+    return {
+      message: () => `result: ${actual}`,
+      pass: actual === 'result',
+    };
+  };
+});
+
+expectError(() => {
+  const lacksMessage: MatcherFunction = (actual: unknown) => {
+    return {
+      pass: actual === 'result',
+    };
+  };
+});
+
+expectError(() => {
+  const lacksPass: MatcherFunction = (actual: unknown) => {
+    return {
+      message: () => `result: ${actual}`,
+    };
+  };
+});
+
+type ToBeWithinRange = (
+  this: MatcherState,
+  actual: unknown,
+  floor: number,
+  ceiling: number,
+) => any;
+
+const toBeWithinRange: MatcherFunction<[floor: number, ceiling: number]> = (
+  actual: unknown,
+  floor: unknown,
+  ceiling: unknown,
+) => {
+  return {
+    message: () => `actual ${actual}; range ${floor}-${ceiling}`,
+    pass: true,
+  };
+};
+
+expectAssignable<ToBeWithinRange>(toBeWithinRange);
+
+type AllowOmittingExpected = (this: MatcherState, actual: unknown) => any;
+
+const allowOmittingExpected: MatcherFunction = (
+  actual: unknown,
+  ...expect: Array<unknown>
+) => {
+  if (expect.length !== 0) {
+    throw new Error('This matcher does not take any expected argument.');
+  }
+
+  return {
+    message: () => `actual ${actual}`,
+    pass: true,
+  };
+};
+
+expectAssignable<AllowOmittingExpected>(allowOmittingExpected);
+
+// MatcherState
+
+const toHaveContext: MatcherFunction = function (
+  actual: unknown,
+  ...expect: Array<unknown>
+) {
+  expectType<MatcherState>(this);
+
+  if (expect.length !== 0) {
+    throw new Error('This matcher does not take any expected argument.');
+  }
+
+  return {
+    message: () => `result: ${actual}`,
+    pass: actual === 'result',
+  };
+};
+
+interface CustomState extends MatcherState {
+  customMethod(): void;
+}
+
+const customContext: MatcherFunctionWithState<CustomState> = function (
+  actual: unknown,
+  ...expect: Array<unknown>
+) {
+  expectType<CustomState>(this);
+  expectType<void>(this.customMethod());
+
+  if (expect.length !== 0) {
+    throw new Error('This matcher does not take any expected argument.');
+  }
+
+  return {
+    message: () => `result: ${actual}`,
+    pass: actual === 'result',
+  };
+};
+
+type CustomStateAndExpected = (
+  this: CustomState,
+  actual: unknown,
+  count: number,
+) => any;
+
+const customStateAndExpected: MatcherFunctionWithState<
+  CustomState,
+  [count: number]
+> = function (actual: unknown, count: unknown) {
+  expectType<CustomState>(this);
+  expectType<void>(this.customMethod());
+
+  return {
+    message: () => `count: ${count}`,
+    pass: actual === count,
+  };
+};
+
+expectAssignable<CustomStateAndExpected>(customStateAndExpected);

packages/expect/src/index.ts

@@ -52,9 +52,10 @@ import type {
 export type {
   AsymmetricMatchers,
   Expect,
+  MatcherFunction,
+  MatcherFunctionWithState,
   MatcherState,
   Matchers,
-  RawMatcherFn,
 } from './types';
 
 export class JestAssertionError extends Error {

packages/expect/src/types.ts

@@ -20,16 +20,29 @@ export type AsyncExpectationResult = Promise<SyncExpectationResult>;
 
 export type ExpectationResult = SyncExpectationResult | AsyncExpectationResult;
 
-export type RawMatcherFn<T extends MatcherState = MatcherState> = {
-  (this: T, actual: any, expected: any, options?: any): ExpectationResult;
+export type MatcherFunctionWithState<
+  State extends MatcherState = MatcherState,
+  Expected extends Array<any> = [] /** TODO should be: extends Array<unknown> = [] */,
+> = (this: State, actual: unknown, ...expected: Expected) => ExpectationResult;
+
+export type MatcherFunction<Expected extends Array<unknown> = []> =
+  MatcherFunctionWithState<MatcherState, Expected>;
+
+// TODO should be replaced with `MatcherFunctionWithContext`
+export type RawMatcherFn<State extends MatcherState = MatcherState> = {
+  (this: State, actual: any, ...expected: Array<any>): ExpectationResult;
   /** @internal */
   [INTERNAL_MATCHER_FLAG]?: boolean;
 };
 
+export type MatchersObject<T extends MatcherState = MatcherState> = {
+  [name: string]: RawMatcherFn<T>;
+};
+
 export type ThrowingMatcherFn = (actual: any) => void;
 export type PromiseMatcherFn = (actual: any) => Promise<void>;
 
-export type MatcherState = {
+export interface MatcherState {
   assertionCalls: number;
   currentTestName?: string;
   dontThrow?(): void;
@@ -48,17 +61,15 @@ export type MatcherState = {
     iterableEquality: Tester;
     subsetEquality: Tester;
   };
-};
+}
 
 export interface AsymmetricMatcher {
   asymmetricMatch(other: unknown): boolean;
   toString(): string;
   getExpectedType?(): string;
   toAsymmetricMatcher?(): string;
 }
-export type MatchersObject<T extends MatcherState = MatcherState> = {
-  [name: string]: RawMatcherFn<T>;
-};
+
 export type ExpectedAssertionsErrors = Array<{
   actual: string | number;
   error: Error;
@@ -189,6 +200,10 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
    * For comparing floating point numbers.
    */
   toBeLessThanOrEqual(expected: number | bigint): R;
+  /**
+   * Used to check that a variable is NaN.
+   */
+  toBeNaN(): R;
   /**
    * This is the same as `.toBe(null)` but the error messages are a bit nicer.
    * So use `.toBeNull()` when you want to check that something is null.
@@ -204,10 +219,6 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
    * Used to check that a variable is undefined.
    */
   toBeUndefined(): R;
-  /**
-   * Used to check that a variable is NaN.
-   */
-  toBeNaN(): R;
   /**
    * Used when you want to check that an item is in a list.
    * For testing the items in the list, this uses `===`, a strict equality check.

packages/jest-jasmine2/src/jestExpect.ts

@@ -7,7 +7,7 @@
 
 /* eslint-disable local/prefer-spread-eventually */
 
-import {type MatcherState, type RawMatcherFn, expect} from 'expect';
+import {type MatcherState, expect} from 'expect';
 import {
   addSerializer,
   toMatchInlineSnapshot,
@@ -41,23 +41,15 @@ export default function jestExpect(config: {expand: boolean}): void {
       jestMatchersObject[name] = function (
         this: MatcherState,
         ...args: Array<unknown>
-      ): RawMatcherFn {
+      ) {
         // use "expect.extend" if you need to use equality testers (via this.equal)
         const result = jasmineMatchersObject[name](null, null);
         // if there is no 'negativeCompare', both should be handled by `compare`
         const negativeCompare = result.negativeCompare || result.compare;
 
         return this.isNot
-          ? negativeCompare.apply(
-              null,
-              // @ts-expect-error
-              args,
-            )
-          : result.compare.apply(
-              null,
-              // @ts-expect-error
-              args,
-            );
+          ? negativeCompare.apply(null, args)
+          : result.compare.apply(null, args);
       };
     });
 

packages/jest-jasmine2/src/types.ts

@@ -7,7 +7,7 @@
 
 import type {AssertionError} from 'assert';
 import type {Config} from '@jest/types';
-import type {Expect, RawMatcherFn} from 'expect';
+import type {Expect} from 'expect';
 import type CallTracker from './jasmine/CallTracker';
 import type Env from './jasmine/Env';
 import type JsApiReporter from './jasmine/JsApiReporter';
@@ -48,8 +48,8 @@ export interface Spy extends Record<string, any> {
 
 type JasmineMatcher = {
   (matchersUtil: unknown, context: unknown): JasmineMatcher;
-  compare: () => RawMatcherFn;
-  negativeCompare: () => RawMatcherFn;
+  compare(...args: Array<unknown>): unknown;
+  negativeCompare(...args: Array<unknown>): unknown;
 };
 
 export type JasmineMatchersObject = {[id: string]: JasmineMatcher};