Add new Required<T, K> as the opposite of Optional<T, K> (#101)

piotrwitek · Sep 24, 2019 · 495fd1b · 495fd1b
1 parent cd294f2
commit 495fd1b
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Showing 6 changed files with 83 additions and 3 deletions.
diff --git a/README.md b/README.md
@@ -91,7 +91,7 @@ Issues can be funded by anyone and the money will be transparently distributed t
 * [`OptionalKeys<T>`](#optionalkeyst)
 * [`Partial<T>`](#partialt) _(built-in)_
 * [`DeepPartial<T>`](#deeppartialt)
-* [`Required<T>`](#requiredt) _(built-in)_
+* [`Required<T, K>`](#requiredt)
 * [`DeepRequired<T>`](#deeprequiredt)
 * [`Readonly<T>`](#readonlyt) _(built-in)_
 * [`DeepReadonly<T>`](#deepreadonlyt)
@@ -621,9 +621,22 @@ Make all properties of object type optional
 
 [⇧ back to top](#table-of-contents)
 
-### `Required<T>`
+### `Required<T, K>`
 
-Make all properties of object type non-optional
+From `T` make a set of properties by key `K` become required
+
+**Usage:**
+
+```ts
+import { Required } from 'utility-types';
+
+type Props = { name?: string; age?: number; visible?: boolean; };
+
+// Expect: { name: string; age: number; visible: boolean; }
+type Props = Required<Props>
+// Expect: { name?: string; age: number; visible: boolean; }
+type Props = Required<Props, 'age' | 'visible'>;
+```
 
 [⇧ back to top](#table-of-contents)
 

diff --git a/src/__snapshots__/mapped-types.spec.ts.snap b/src/__snapshots__/mapped-types.spec.ts.snap
@@ -4,6 +4,17 @@ exports[`Assign const result: Assign<{}, Omit<T, 'age'>> = rest 1`] = `"any"`;
 
 exports[`Assign testType<Assign<Props, NewProps>>() 1`] = `"Pick<Pick<Props, \\"name\\" | \\"visible\\"> & Pick<NewProps, \\"age\\"> & Pick<NewProps, \\"other\\">, \\"name\\" | \\"age\\" | \\"visible\\" | \\"other\\">"`;
 
+exports[`AugmentedRequired testType<AugmentedRequired<Partial<Props>, 'age' | 'visible'>>({
+      age: 99,
+      visible: true,
+    }) 1`] = `"AugmentedRequired<Partial<Props>, \\"age\\" | \\"visible\\">"`;
+
+exports[`AugmentedRequired testType<AugmentedRequired<Partial<Props>>>({
+      name: 'Yolo',
+      age: 99,
+      visible: true,
+    }) 1`] = `"AugmentedRequired<Partial<Props>, \\"name\\" | \\"age\\" | \\"visible\\">"`;
+
 exports[`Brand testType<Brand<number, 'USD'>>() 1`] = `"Brand<number, \\"USD\\">"`;
 
 exports[`DeepNonNullable testType<

diff --git a/src/index.ts b/src/index.ts
@@ -50,6 +50,7 @@ export {
   Unionize,
   ValuesType,
   WritableKeys,
+  AugmentedRequired as Required,
 } from './mapped-types';
 
 export * from './type-guards';

diff --git a/src/mapped-types.spec.snap.ts b/src/mapped-types.spec.snap.ts
@@ -40,6 +40,7 @@ import {
   OmitByValueExact,
   Optional,
   ValuesType,
+  AugmentedRequired,
 } from './mapped-types';
 
 /**
@@ -527,3 +528,19 @@ type RequiredOptionalProps = {
   // @dts-jest:pass:snap -> number
   testType<ValuesType<Uint32Array>>();
 }
+
+// @dts-jest:group AugmentedRequired
+{
+  // @dts-jest:pass:snap -> AugmentedRequired<Partial<Props>, "name" | "age" | "visible">
+  testType<AugmentedRequired<Partial<Props>>>({
+    name: 'Yolo',
+    age: 99,
+    visible: true,
+  });
+
+  // @dts-jest:pass:snap -> AugmentedRequired<Partial<Props>, "age" | "visible">
+  testType<AugmentedRequired<Partial<Props>, 'age' | 'visible'>>({
+    age: 99,
+    visible: true,
+  });
+}
diff --git a/src/mapped-types.spec.ts b/src/mapped-types.spec.ts
@@ -40,6 +40,7 @@ import {
   OmitByValueExact,
   Optional,
   ValuesType,
+  AugmentedRequired,
 } from './mapped-types';
 
 /**
@@ -527,3 +528,19 @@ type RequiredOptionalProps = {
   // @dts-jest:pass:snap
   testType<ValuesType<Uint32Array>>();
 }
+
+// @dts-jest:group AugmentedRequired
+{
+  // @dts-jest:pass:snap
+  testType<AugmentedRequired<Partial<Props>>>({
+    name: 'Yolo',
+    age: 99,
+    visible: true,
+  });
+
+  // @dts-jest:pass:snap
+  testType<AugmentedRequired<Partial<Props>, 'age' | 'visible'>>({
+    age: 99,
+    visible: true,
+  });
+}
diff --git a/src/mapped-types.ts b/src/mapped-types.ts
@@ -614,3 +614,24 @@ export type ValuesType<
   : T extends object
   ? T[keyof T]
   : never;
+
+/**
+ * Required
+ * @desc From `T` make a set of properties by key `K` become required
+ * @example
+ *    type Props = {
+ *      name?: string;
+ *      age?: number;
+ *      visible?: boolean;
+ *    };
+ *
+ *    // Expect: { name: string; age: number; visible: boolean; }
+ *    type Props = Required<Props>;
+ *
+ *    // Expect: { name?: string; age: number; visible: boolean; }
+ *    type Props = Required<Props, 'age' | 'visible'>;
+ */
+export type AugmentedRequired<
+  T extends object,
+  K extends keyof T = keyof T
+> = Omit<T, K> & Required<Pick<T, K>>;