Fix implementation of .readonly()

README.md

@@ -295,14 +295,6 @@ type Post = {title: string; content: string}
 expectTypeOf<Post>().readonly().toEqualTypeOf<Readonly<Post>>()
 ```
 
-`.readonly` can make specific properties `readonly`:
-
-```typescript
-type Post = {title: string; content: string}
-
-expectTypeOf<Post>().readonly('title').toEqualTypeOf<{readonly title: string; content: string}>()
-```
-
 Make assertions about object properties:
 
 ```typescript

src/index.ts

@@ -676,13 +676,11 @@ export interface BaseExpectTypeOf<Actual, Options extends {positive: boolean}> {
   ) => ExpectTypeOf<Omit<Actual, KeyToOmit>, Options>
 
   /**
-   * Converts specified properties of an object to `readonly`.
-   * If no properties are specified, it defaults
-   * to making all properties `readonly`, similar to the native
-   * TypeScript {@linkcode Readonly} utility type.
+   * Converts all properties of a type to **`readonly`**,
+   * behaving exactly like the TypeScript {@linkcode Readonly} utility type.
    *
    * @example
-   * <caption>#### Make all properties `readonly` (default behavior)</caption>
+   * <caption>#### Create a **`readonly`** version of a type</caption>
    *
    * ```ts
    * import { expectTypeOf } from 'expect-type'
@@ -695,35 +693,11 @@ export interface BaseExpectTypeOf<Actual, Options extends {positive: boolean}> {
    * expectTypeOf<Post>().readonly().toEqualTypeOf<Readonly<Post>>()
    * ```
    *
-   * @example
-   * <caption>#### Make specific properties `readonly`</caption>
-   *
-   * ```ts
-   * import { expectTypeOf } from 'expect-type'
-   *
-   * type Post = {
-   *   title: string
-   *   content: string
-   * }
-   *
-   * expectTypeOf<Post>()
-   *   .readonly('title')
-   *   .toEqualTypeOf<{ readonly title: string; content: string }>()
-   * ```
+   * @returns The type with all properties made **`readonly`**, mirroring the behavior of TypeScript's {@linkcode Readonly} utility.
    *
-   * @param propertiesToMakeReadonly - The specific properties of the {@linkcode Actual} type to be made `readonly`. If omitted, all properties will be made `readonly`, behaving like the TypeScript {@linkcode Readonly} utility type.
-   * @returns the type with the specified properties made `readonly`. If no properties are specified, all properties will be made `readonly`, behaving like the TypeScript {@linkcode Readonly} utility.
-   *
-   * @template PropertiesToMakeReadonly - The keys of the __`Actual`__ type to be made `readonly`. Defaults to `never`, meaning no specific properties are targeted unless explicitly defined.
-   *
-   * @since 1.0.0
+   * @since 1.1.0
    */
-  readonly<PropertiesToMakeReadonly extends keyof Actual = never>(
-    propertiesToMakeReadonly?: PropertiesToMakeReadonly,
-  ): ExpectTypeOf<
-    IsNever<PropertiesToMakeReadonly> extends true ? Readonly<Actual> : SetReadonly<Actual, PropertiesToMakeReadonly>,
-    Options
-  >
+  readonly(): ExpectTypeOf<Readonly<Actual>, Options>
 
   /**
    * Extracts a certain function argument with `.parameter(number)` call to

src/utils.ts

@@ -250,7 +250,7 @@ export type UnionToTuple<Union> = TuplifyUnion<Union>
  * expectTypeOf(undefined).not.toMatchTypeOf<AnyNonNullishValue>()
  * ```
  *
- * @since 1.0.0
+ * @since 1.1.0
  * @internal
  */
 type AnyNonNullishValue = NonNullable<unknown>
@@ -267,7 +267,7 @@ type AnyNonNullishValue = NonNullable<unknown>
  * const sum = ((a: number, b: number): number => a + b) satisfies AnyFunction
  * ```
  *
- * @since 1.0.0
+ * @since 1.1.0
  * @internal
  */
 type AnyFunction = (...args: any[]) => any
@@ -308,7 +308,7 @@ type AnyFunction = (...args: any[]) => any
  * }>()
  * ```
  *
- * @since 1.0.0
+ * @since 1.1.0
  * @internal
  * @see {@link https://github.com/sindresorhus/type-fest/blob/main/source/simplify.d.ts | Source}
  */
@@ -348,7 +348,7 @@ type Simplify<TypeToFlatten> = TypeToFlatten extends AnyFunction
  * @template BaseType - The base type whose properties will be transformed to `readonly`.
  * @template KeysToBecomeReadonly - The keys of the __`BaseType`__ to be made `readonly`.
  *
- * @since 1.0.0
+ * @since 1.1.0
  */
 export type SetReadonly<BaseType, KeysToBecomeReadonly extends keyof BaseType> = BaseType extends unknown
   ? Simplify<Omit<BaseType, KeysToBecomeReadonly> & Readonly<Pick<BaseType, KeysToBecomeReadonly>>>

test/usage.test.ts

@@ -191,12 +191,6 @@ test('Use `.readonly` to create a `readonly` version of a type', () => {
   expectTypeOf<Post>().readonly().toEqualTypeOf<Readonly<Post>>()
 })
 
-test('`.readonly` can make specific properties `readonly`', () => {
-  type Post = {title: string; content: string}
-
-  expectTypeOf<Post>().readonly('title').toEqualTypeOf<{readonly title: string; content: string}>()
-})
-
 test('Make assertions about object properties', () => {
   const obj = {a: 1, b: ''}