feat(expect, @jest/expect): infer type of *ReturnedWith matchers argument (#13278)

Author: mrazauskas

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 
 - `[expect, @jest/expect]` support type inference for function parameters in `CalledWith` assertions ([#13268](https://github.com/facebook/jest/pull/13268))
+- `[expect, @jest/expect]` Infer type of `*ReturnedWith` matchers argument ([#13278](https://github.com/facebook/jest/pull/13278))
 - `[@jest/environment, jest-runtime]` Allow `jest.requireActual` and `jest.requireMock` to take a type argument ([#13253](https://github.com/facebook/jest/pull/13253))
 - `[@jest/environment]` Allow `jest.mock` and `jest.doMock` to take a type argument ([#13254](https://github.com/facebook/jest/pull/13254))
 - `[@jest/fake-timers]` Add `jest.now()` to return the current fake clock time ([#13244](https://github.com/facebook/jest/pull/13244), [13246](https://github.com/facebook/jest/pull/13246))

packages/expect/__typetests__/expect.test.ts

@@ -16,7 +16,8 @@ import {
 } from 'expect';
 import type * as jestMatcherUtils from 'jest-matcher-utils';
 
-type M = Matchers<void>;
+type M = Matchers<void, unknown>;
+type N = Matchers<void>;
 
 expectError(() => {
   type E = Matchers;

packages/expect/src/types.ts

@@ -141,15 +141,15 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
   /**
    * Ensure that the last call to a mock function has returned a specified value.
    */
-  lastReturnedWith(expected: unknown): R;
+  lastReturnedWith(expected: ReturnType<EnsureFunctionLike<T>>): R;
   /**
    * Ensure that a mock function is called with specific arguments on an Nth call.
    */
   nthCalledWith(nth: number, ...expected: Parameters<EnsureFunctionLike<T>>): R;
   /**
    * Ensure that the nth call to a mock function has returned a specified value.
    */
-  nthReturnedWith(nth: number, expected: unknown): R;
+  nthReturnedWith(nth: number, expected: ReturnType<EnsureFunctionLike<T>>): R;
   /**
    * Checks that a value is what you expect. It calls `Object.is` to compare values.
    * Don't use `toBe` with floating-point numbers.
@@ -267,7 +267,7 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
    * If the last call to the mock function threw an error, then this matcher will fail
    * no matter what value you provided as the expected return value.
    */
-  toHaveLastReturnedWith(expected: unknown): R;
+  toHaveLastReturnedWith(expected: ReturnType<EnsureFunctionLike<T>>): R;
   /**
    * Used to check that an object has a `.length` property
    * and it is set to a certain numeric value.
@@ -278,7 +278,10 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
    * If the nth call to the mock function threw an error, then this matcher will fail
    * no matter what value you provided as the expected return value.
    */
-  toHaveNthReturnedWith(nth: number, expected: unknown): R;
+  toHaveNthReturnedWith(
+    nth: number,
+    expected: ReturnType<EnsureFunctionLike<T>>,
+  ): R;
   /**
    * Use to check if property at provided reference keyPath exists for an object.
    * For checking deeply nested properties in an object you may use dot notation or an array containing
@@ -308,7 +311,7 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
   /**
    * Use to ensure that a mock function returned a specific value.
    */
-  toHaveReturnedWith(expected: unknown): R;
+  toHaveReturnedWith(expected: ReturnType<EnsureFunctionLike<T>>): R;
   /**
    * Check that a string matches a regular expression.
    */
@@ -330,7 +333,7 @@ export interface Matchers<R extends void | Promise<void>, T = unknown> {
   /**
    * Ensure that a mock function has returned a specified value at least once.
    */
-  toReturnWith(expected: unknown): R;
+  toReturnWith(expected: ReturnType<EnsureFunctionLike<T>>): R;
   /**
    * Use to test that objects have the same types as well as structure.
    */

packages/jest-types/__typetests__/expect.test.ts

@@ -278,21 +278,44 @@ expectError(expect(jest.fn()).toHaveReturnedTimes(true));
 expectError(expect(jest.fn()).toHaveReturnedTimes());
 
 expectType<void>(expect(jest.fn()).toReturnWith('value'));
+expectType<void>(expect(jest.fn<() => string>()).toReturnWith('value'));
+expectError(expect(jest.fn<() => number>()).toReturnWith('value'));
+expectError(expect(123).toReturnWith('value'));
 expectError(expect(jest.fn()).toReturnWith());
+
 expectType<void>(expect(jest.fn()).toHaveReturnedWith(123));
+expectType<void>(expect(jest.fn<() => number>()).toHaveReturnedWith(123));
+expectError(expect(jest.fn<() => string>()).toHaveReturnedWith(123));
+expectError(expect(123).toHaveReturnedWith(123));
 expectError(expect(jest.fn()).toHaveReturnedWith());
 
 expectType<void>(expect(jest.fn()).lastReturnedWith('value'));
+expectType<void>(expect(jest.fn<() => string>()).lastReturnedWith('value'));
+expectError(expect(jest.fn<() => number>()).lastReturnedWith('value'));
+expectError(expect(123).lastReturnedWith('value'));
 expectError(expect(jest.fn()).lastReturnedWith());
+
 expectType<void>(expect(jest.fn()).toHaveLastReturnedWith(123));
+expectType<void>(expect(jest.fn<() => number>()).toHaveLastReturnedWith(123));
+expectError(expect(jest.fn<() => string>()).toHaveLastReturnedWith(123));
+expectError(expect(123).toHaveLastReturnedWith(123));
 expectError(expect(jest.fn()).toHaveLastReturnedWith());
 
 expectType<void>(expect(jest.fn()).nthReturnedWith(1, 'value'));
+expectType<void>(expect(jest.fn<() => string>()).nthReturnedWith(2, 'value'));
+expectError(expect(jest.fn<() => number>()).nthReturnedWith(3, 'value'));
+expectError(expect(123).nthReturnedWith(4, 'value'));
+expectError(expect(123).nthReturnedWith(5));
 expectError(expect(jest.fn()).nthReturnedWith());
-expectError(expect(jest.fn()).nthReturnedWith(2));
+
 expectType<void>(expect(jest.fn()).toHaveNthReturnedWith(1, 'value'));
+expectType<void>(
+  expect(jest.fn<() => string>()).toHaveNthReturnedWith(2, 'value'),
+);
+expectError(expect(jest.fn<() => number>()).toHaveNthReturnedWith(3, 'value'));
+expectError(expect(123).toHaveNthReturnedWith(4, 'value'));
+expectError(expect(123).toHaveNthReturnedWith(5));
 expectError(expect(jest.fn()).toHaveNthReturnedWith());
-expectError(expect(jest.fn()).toHaveNthReturnedWith(2));
 
 // snapshot matchers