Add RequireAllOrNone type

index.d.ts

@@ -11,6 +11,7 @@ export {Merge} from './source/merge';
 export {MergeExclusive} from './source/merge-exclusive';
 export {RequireAtLeastOne} from './source/require-at-least-one';
 export {RequireExactlyOne} from './source/require-exactly-one';
+export {RequireAllOrNone} from './source/require-all-or-none';
 export {PartialDeep} from './source/partial-deep';
 export {ReadonlyDeep} from './source/readonly-deep';
 export {LiteralUnion} from './source/literal-union';

readme.md

@@ -100,6 +100,7 @@ Click the type names for complete docs.
 - [`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.
 - [`RequireExactlyOne`](source/require-exactly-one.d.ts) - Create a type that requires exactly a single key of the given keys and disallows more.
+- [`RequireAllOrNone`](source/require-all-or-none.d.ts) - Create a type that requires all of the given keys or none of the given keys.
 - [`PartialDeep`](source/partial-deep.d.ts) - Create a deeply optional version of another type. Use [`Partial<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1401-L1406) if you only need one level deep.
 - [`ReadonlyDeep`](source/readonly-deep.d.ts) - Create a deeply immutable version of an `object`/`Map`/`Set`/`Array` type. Use [`Readonly<T>`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1415-L1420) if you only need one level deep.
 - [`LiteralUnion`](source/literal-union.d.ts) - Create a union type by combining primitive types and literal types without sacrificing auto-completion in IDEs for the literal type part of the union. Workaround for [Microsoft/TypeScript#29729](https://github.com/Microsoft/TypeScript/issues/29729).

source/require-all-or-none.ts

@@ -0,0 +1,36 @@
+/**
+Create a type that requires all of the given keys or none of the given keys. The remaining keys are kept as is.
+
+Use-cases:
+- Creating interfaces for components with mutually-inclusive keys.
+
+The caveat with `RequireAllOrNone` is that TypeScript doesn't always know at compile time every key that will exist at runtime. Therefore `RequireAllOrNone` can't do anything to prevent extra keys it doesn't know about.
+
+@example
+```
+import {RequireAllOrNone} from 'type-fest';
+
+type Responder = {
+	text?: () => string;
+	json?: () => string;
+	secure: boolean;
+};
+
+const responder1: RequireAllOrNone<Responder, 'text' | 'json'> = {
+	secure: true
+};
+
+const responder2: RequireAllOrNone<Responder, 'text' | 'json'> = {
+	text: () => '{"message": "hi"}',
+	json: () => '{"message": "ok"}',
+	secure: true
+};
+```
+
+@category Utilities
+*/
+export type RequireAllOrNone<ObjectType, KeysType extends keyof ObjectType = never> = (
+	| Required<Pick<ObjectType, KeysType>> // Require all of the given keys.
+	| Partial<Record<KeysType, never>> // Require none of the given keys.
+) &
+	Omit<ObjectType, KeysType>; // The rest of the keys.

test-d/require-all-or-none.ts

@@ -0,0 +1,24 @@
+import {expectError, expectAssignable} from 'tsd';
+import {RequireAllOrNone} from '../index';
+
+type SystemMessages = {
+	default: string;
+
+	macos: string;
+	linux: string;
+
+	optional?: string;
+};
+
+type ValidMessages = RequireAllOrNone<SystemMessages, 'macos' | 'linux'>;
+const test = (_: ValidMessages): void => {}; // eslint-disable-line @typescript-eslint/no-empty-function
+
+test({default: 'hello'});
+test({macos: 'yo', linux: 'sup', optional: 'howdy', default: 'hello'});
+
+expectError(test({}));
+expectError(test({macos: 'hey', default: 'hello'}));
+expectError(test({linux: 'hey', default: 'hello'}));
+
+declare const oneWithoutKeys: RequireAllOrNone<{a: number; b: number}>;
+expectAssignable<{a: number; b: number}>(oneWithoutKeys);