test: add test unit

piotrwitek · May 7, 2019 · f36066b · f36066b
1 parent 42f36a0
commit f36066b
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Showing 3 changed files with 20 additions and 6 deletions.
diff --git a/src/__snapshots__/mapped-types.spec.ts.snap b/src/__snapshots__/mapped-types.spec.ts.snap
@@ -126,6 +126,10 @@ exports[`OmitByValueExact testType<OmitByValueExact<RequiredOptionalProps, undef
 
 exports[`OmitByValueExact testType<OmitByValueExact<T, number>>() 1`] = `"Pick<T, { [Key in keyof T]: [number] extends [T[Key]] ? [T[Key]] extends [T[Key] & number] ? never : Key : Key; }[keyof T]>"`;
 
+exports[`Optional testType<Optional<Props, 'age' | 'visible'>>() 1`] = `"(Pick<Props, \\"name\\" | \\"visible\\"> & { age?: number | undefined; }) | (Pick<Props, \\"name\\" | \\"age\\"> & { visible?: boolean | undefined; })"`;
+
+exports[`Optional testType<Optional<Props>>() 1`] = `"Partial<Props>"`;
+
 exports[`OptionalKeys testType<OptionalKeys<RequiredOptionalProps>>() 1`] = `"\\"opt\\" | \\"optUndef\\""`;
 
 exports[`Overwrite const result: Overwrite<Omit<T, 'age'>, T> = rest 1`] = `"any"`;

diff --git a/src/mapped-types.spec.ts b/src/mapped-types.spec.ts
@@ -38,6 +38,7 @@ import {
   OptionalKeys,
   PickByValueExact,
   OmitByValueExact,
+  Optional,
 } from './mapped-types';
 
 /**
@@ -482,3 +483,12 @@ type RequiredOptionalProps = {
   // @dts-jest:pass:snap
   testType<Brand<number, 'USD'>>();
 }
+
+// @dts-jest:group Optional
+{
+  // @dts-jest:pass:snap
+  testType<Optional<Props>>();
+
+  // @dts-jest:pass:snap
+  testType<Optional<Props, 'age' | 'visible'>>();
+}
diff --git a/src/mapped-types.ts b/src/mapped-types.ts
@@ -561,16 +561,16 @@ export type Brand<T, U> = T & { __brand: U };
  * @example
  *    type Props = {
  *      name: string;
- *      age: string;
- *      height: number;
+ *      age: number;
+ *      visible: boolean;
  *    };
  *
- *    // Expect: { name?: string; age?: string; height?: number; }
+ *    // Expect: { name?: string; age?: number; visible?: boolean; }
  *    type Props = Optional<Props>;
  *
- *    // Expect: { name: string; age?: string; height?: number; }
- *    type Props = Optional<Props, 'age' | 'height'>;
+ *    // Expect: { name: string; age?: number; visible?: boolean; }
+ *    type Props = Optional<Props, 'age' | 'visible'>;
  */
-export type Optional<T extends {}, K = keyof any> = K extends (keyof T)
+export type Optional<T extends object, K = keyof any> = K extends (keyof T)
   ? (Omit<T, K> & { [key in K]?: T[key] })
   : Partial<T>;