Rename Mutable to Writable (#398)

index.d.ts

@@ -7,6 +7,7 @@ export * from './source/observable-like';
 // Utilities
 export {Except} from './source/except';
 export {Mutable} from './source/mutable';
+export {Writable} from './source/writable';
 export {Merge} from './source/merge';
 export {MergeExclusive} from './source/merge-exclusive';
 export {RequireAtLeastOne} from './source/require-at-least-one';

readme.md

@@ -161,7 +161,7 @@ Click the type names for complete docs.
 ### Utilities
 
 - [`Except`](source/except.d.ts) - Create a type from an object type without certain keys. This is a stricter version of [`Omit`](https://www.typescriptlang.org/docs/handbook/utility-types.html#omittype-keys).
-- [`Mutable`](source/mutable.d.ts) - Create a type that strips `readonly` from all or some of an object's keys. The inverse of `Readonly<T>`.
+- [`Writable`](source/writable.d.ts) - Create a type that strips `readonly` from all or some of an object's keys. The inverse of `Readonly<T>`. Formerly named `Mutable`.
 - [`Merge`](source/merge.d.ts) - Merge two types into a new type. Keys of the second type overrides keys of the first type.
 - [`MergeExclusive`](source/merge-exclusive.d.ts) - Create a type that has mutually exclusive keys.
 - [`RequireAtLeastOne`](source/require-at-least-one.d.ts) - Create a type that requires at least one of the given keys.

source/mutable.d.ts

@@ -1,40 +1,5 @@
-import type {Except} from './except';
-import type {Simplify} from './simplify';
+import type {Writable} from './writable';
 
-/**
-Create a type that strips `readonly` from all or some of an object's keys. Inverse of `Readonly<T>`.
-
-This can be used to [store and mutate options within a class](https://github.com/sindresorhus/pageres/blob/4a5d05fca19a5fbd2f53842cbf3eb7b1b63bddd2/source/index.ts#L72), [edit `readonly` objects within tests](https://stackoverflow.com/questions/50703834), [construct a `readonly` object within a function](https://github.com/Microsoft/TypeScript/issues/24509), or to define a single model where the only thing that changes is whether or not some of the keys are mutable.
-
-@example
-```
-import type {Mutable} from 'type-fest';
-
-type Foo = {
-	readonly a: number;
-	readonly b: readonly string[]; // To show that only the mutability status of the properties, not their values, are affected.
-	readonly c: boolean;
-};
-
-const mutableFoo: Mutable<Foo> = {a: 1, b: ['2'], c: true};
-mutableFoo.a = 3;
-mutableFoo.b[0] = 'new value'; // Will still fail as the value of property "b" is still a readonly type.
-mutableFoo.b = ['something']; // Will work as the "b" property itself is no longer readonly.
-
-type SomeMutable = Mutable<Foo, 'b' | 'c'>;
-// type SomeMutable = {
-// 	readonly a: number;
-// 	b: readonly string[]; // It's now mutable. The type of the property remains unaffected.
-// 	c: boolean; // It's now mutable.
-// }
-```
-
-@category Object
-*/
+/** @deprecated @see Writable */
 export type Mutable<BaseType, Keys extends keyof BaseType = keyof BaseType> =
-	Simplify<
-		// Pick just the keys that are not mutable from the base type.
-		Except<BaseType, Keys> &
-		// Pick the keys that should be mutable from the base type and make them mutable by removing the `readonly` modifier from the key.
-		{-readonly [KeyType in keyof Pick<BaseType, Keys>]: Pick<BaseType, Keys>[KeyType]}
-	>;
+	Writable<BaseType, Keys>;

source/writable.d.ts

@@ -0,0 +1,40 @@
+import type {Except} from './except';
+import type {Simplify} from './simplify';
+
+/**
+Create a type that strips `readonly` from all or some of an object's keys. Inverse of `Readonly<T>`.
+
+This can be used to [store and mutate options within a class](https://github.com/sindresorhus/pageres/blob/4a5d05fca19a5fbd2f53842cbf3eb7b1b63bddd2/source/index.ts#L72), [edit `readonly` objects within tests](https://stackoverflow.com/questions/50703834), [construct a `readonly` object within a function](https://github.com/Microsoft/TypeScript/issues/24509), or to define a single model where the only thing that changes is whether or not some of the keys are writable.
+
+@example
+```
+import type {Writable} from 'type-fest';
+
+type Foo = {
+	readonly a: number;
+	readonly b: readonly string[]; // To show that only the mutability status of the properties, not their values, are affected.
+	readonly c: boolean;
+};
+
+const writableFoo: Writable<Foo> = {a: 1, b: ['2'], c: true};
+writableFoo.a = 3;
+writableFoo.b[0] = 'new value'; // Will still fail as the value of property "b" is still a readonly type.
+writableFoo.b = ['something']; // Will work as the "b" property itself is no longer readonly.
+
+type SomeWritable = Writable<Foo, 'b' | 'c'>;
+// type SomeWritable = {
+// 	readonly a: number;
+// 	b: readonly string[]; // It's now writable. The type of the property remains unaffected.
+// 	c: boolean; // It's now writable.
+// }
+```
+
+@category Object
+*/
+export type Writable<BaseType, Keys extends keyof BaseType = keyof BaseType> =
+	Simplify<
+		// Pick just the keys that are not writable from the base type.
+		Except<BaseType, Keys> &
+		// Pick the keys that should be writable from the base type and make them writable by removing the `readonly` modifier from the key.
+		{-readonly [KeyType in keyof Pick<BaseType, Keys>]: Pick<BaseType, Keys>[KeyType]}
+	>;

test-d/writable.ts

@@ -0,0 +1,28 @@
+import {expectType, expectError} from 'tsd';
+import type {Writable} from '../index';
+
+type Foo = {
+	readonly a: number;
+	readonly b: string;
+};
+
+const ab: Writable<Foo> = {a: 1, b: '2'};
+ab.a = 2;
+const ab2: Writable<Readonly<Foo>> = ab;
+ab2.a = 2;
+
+// Update one writable and one readonly to writable, leaving one property unaffected.
+declare const variation1: Writable<{readonly a: number; b: string; readonly c: boolean}, 'b' | 'c'>;
+expectType<{readonly a: number; b: string; c: boolean}>(variation1);
+
+// Update two readonly to writable, leaving one property unaffected.
+declare const variation2: Writable<{readonly a: number; readonly b: string; readonly c: boolean}, 'a' | 'b'>;
+expectType<{a: number; b: string; readonly c: boolean}>(variation2);
+
+// Three writable remain writable.
+declare const variation3: Writable<{a: number; b: string; c: boolean}, 'a' | 'b' | 'c'>;
+expectType<{a: number; b: string; c: boolean}>(variation3);
+
+// Check if type changes raise an error even if readonly and writable are applied correctly.
+declare const variation4: Writable<{readonly a: number; b: string; readonly c: boolean}, 'b' | 'c'>;
+expectError<{readonly a: boolean; b: string; c: boolean}>(variation4);