Merge pull request #427 from styled-system/fix-space-proptypes

Copy properties of function argument in mapProps - fixes #416

src/index.js

@@ -122,7 +122,13 @@ export const compose = (...funcs) => {
   return func
 }
 
-export const mapProps = mapper => func => props => func(mapper(props))
+export const mapProps = mapper => func => {
+  const next = props => func(mapper(props))
+  for (const key in func) {
+    next[key] = func[key]
+  }
+  return next
+}
 
 export const variant = ({ key, prop = 'variant' }) => {
   const fn = props => get(props.theme, [key, props[prop]].join('.'), null)

test/index.js

@@ -9,6 +9,7 @@ import {
   compose,
   variant,
   cloneFunction,
+  mapProps,
 } from '../src'
 
 const width = style({
@@ -270,3 +271,9 @@ test('array values longer than breakpoints does not reset returned style object'
     { width: '100%' },
   ])
 })
+
+test('mapProps copies propTypes',  t => {
+  const margin = style({ prop: 'margin' })
+  const func = mapProps(props => props)(margin)
+  t.is(typeof func.propTypes, 'object')
+})

test/styles.js

@@ -215,6 +215,12 @@ test('margin overrides m prop', t => {
   t.deepEqual(styles, [{ margin: '8px' }])
 })
 
+test('space includes propTypes', t => {
+  const { propTypes } = space
+  t.is(typeof propTypes, 'object')
+  t.is(typeof propTypes.m, 'function')
+})
+
 test('size returns width and height', t => {
   const styles = size({
     size: 4,