feat(shape): Support generating objects of fake data

index.d.ts

@@ -203,9 +203,28 @@ declare const tuple: Tuple
 
 export { tuple }
 
+export interface Shape {
+  <Makers extends { [s: string]: Maker<unknown> }>(makers: Makers): (
+    input: Input
+  ) => ShapeReturnType<Makers>
+  <Makers extends { [s: string]: Maker<unknown> }>(
+    input: Input,
+    makers: Makers
+  ): ShapeReturnType<Makers>
+}
+
+declare const shape: Shape
+
+export { shape }
+
 type MakerResult<M> = M extends Maker<infer R> ? R : never
+
 type WeightedMakerResult<M> = M extends WeightedMaker<infer R> ? R : never
 
+type ShapeReturnType<Makers extends { [s: string]: Maker<unknown> }> = {
+  [K in keyof Makers]: MakerResult<Makers[K]>
+}
+
 export type TupleReturnType<Makers extends AnyMakers> = Makers extends Makers1<
   infer V1
 >

index.js

@@ -3,6 +3,7 @@ exports.hash = require('./hash')
 exports.oneOf = require('./oneOf')
 exports.someOf = require('./someOf')
 exports.tuple = require('./tuple')
+exports.shape = require('./shape')
 exports.times = require('./times')
 exports.join = require('./join')
 exports.oneOfWeighted = require('./oneOfWeighted')

index.mjs

@@ -2,6 +2,7 @@ export { default as hash } from './has'
 
 export { default as someOf } from './someOf'
 export { default as tuple } from './tuple'
+export { default as shape } from './shape'
 export { default as times } from './times'
 export { default as join } from './join'
 export { default as oneOf } from './oneOf'

index.test-d.ts

@@ -7,6 +7,7 @@ import {
   float,
   word,
   tuple,
+  shape,
   someOf,
   times,
   join,
@@ -26,6 +27,15 @@ expectType<number | string>(
 )
 expectType<(number | string)[]>(someOf(null, [2, 3], [int, word]))
 expectType<number[]>(times(null, [2, 3], int))
+expectType<{
+  a: number
+  b: string
+}>(
+  shape(null, {
+    a: int,
+    b: word
+  })
+)
 
 // ## constant items
 expectType<[number, string]>(tuple(null, [2, '!']))
@@ -39,6 +49,15 @@ expectType<number | string>(
 )
 expectType<(number | string)[]>(someOf(null, [3, 3], [2, '!']))
 expectType<number[]>(times(null, [2, 3], 23))
+expectType<{
+  a: number
+  b: string
+}>(
+  shape(null, {
+    a: 2,
+    b: '!'
+  })
+)
 
 // ## currying
 expectType<(input: Input) => [number]>(tuple([int]))
@@ -52,6 +71,19 @@ expectType<(input: Input) => number>(
 )
 expectType<(input: Input) => string[]>(someOf([3, 3], ['a', 'b']))
 expectType<(input: Input) => string[]>(times([2, 3], word))
+expectType<
+  (
+    input: Input
+  ) => {
+    a: number
+    b: string
+  }
+>(
+  shape({
+    a: int,
+    b: word
+  })
+)
 
 // ## join: joiner types
 declare function numJoiner(v: (number | string)[]): number

shape.js

@@ -0,0 +1,29 @@
+var hash = require('./hash')
+var resolve = require('./utils/resolve')
+
+var hasOwnProperty = Object.prototype.hasOwnProperty
+
+function shape(a, b) {
+  return b != null ? shapeMain(a, b) : shapeCurried(a)
+}
+
+function shapeMain(input, properties) {
+  var id = hash(input)
+  var results = {}
+
+  for (var k in properties) {
+    if (hasOwnProperty.call(properties, k)) {
+      results[k] = resolve(hash([id, 'shape', k]), properties[k])
+    }
+  }
+
+  return results
+}
+
+function shapeCurried(properties) {
+  return function shapeCurriedFn(input) {
+    return shapeMain(input, properties)
+  }
+}
+
+module.exports = shape