Add resetState to State

.size-snapshot.json

@@ -1,18 +1,18 @@
 {
   "dist/react-powerplug.umd.js": {
-    "bundled": 22187,
-    "minified": 8780,
-    "gzipped": 2415
+    "bundled": 22402,
+    "minified": 8890,
+    "gzipped": 2436
   },
   "dist/react-powerplug.cjs.js": {
-    "bundled": 20000,
-    "minified": 10012,
-    "gzipped": 2407
+    "bundled": 20201,
+    "minified": 10132,
+    "gzipped": 2430
   },
   "dist/react-powerplug.esm.js": {
-    "bundled": 19370,
-    "minified": 9474,
-    "gzipped": 2267,
+    "bundled": 19571,
+    "minified": 9594,
+    "gzipped": 2288,
     "treeshaked": {
       "rollup": {
         "code": 204,

docs/components/State.md

@@ -30,12 +30,16 @@ The onChange event of the State is called whenever the state changes.
 
 ## State Children Props
 
-TL;DR: `{ state, setState }`
+TL;DR: `{ state, setState, resetState }`
 
 **state**  
 `object`  
 Your state
 
 **setState**  
-`(object | (state: object) => object) => void`  
+`(object | (state: object) => object, cb?: () => void) => void`  
 State setter. Is the [setState](https://facebook.github.io/react/docs/react-component.html#setstate) from React.Component.
+
+**resetState**  
+`(cb?: () => void) => void`
+Resets state to initial value (_the value equal to current! initial prop_).

src/components/State.js

@@ -16,10 +16,15 @@ class State extends Component {
     })
   }
 
+  _resetState = (cb = noop) => {
+    this._setState({ ...this.props.initial }, cb)
+  }
+
   render() {
     return renderProps(this.props, {
       state: this.state,
       setState: this._setState,
+      resetState: this._resetState,
     })
   }
 }

src/index.js.flow

@@ -210,6 +210,7 @@ type StateChange<T> = T => void
 type StateRender<T> = ({|
   state: T,
   setState: (updated: $Shape<T> | (T => $Shape<T>), cb?: () => void) => void,
+  resetState: (cb?: () => void) => void,
 |}) => React.Node
 
 type StateProps<T> =

tests/components/State.test.js

@@ -5,12 +5,16 @@ import { lastCallArg } from './utils'
 
 test('<State />', () => {
   const renderFn = jest.fn().mockReturnValue(null)
-  TestRenderer.create(<State initial={{ myValue: 1 }} render={renderFn} />)
+
+  const testRenderer = TestRenderer.create(
+    <State initial={{ myValue: 1 }} render={renderFn} />
+  )
 
   // Initial values
   expect(renderFn).lastCalledWith({
     state: { myValue: 1 },
     setState: expect.any(Function),
+    resetState: expect.any(Function),
   })
 
   lastCallArg(renderFn).setState({ myValue: 2 })
@@ -19,6 +23,27 @@ test('<State />', () => {
   expect(renderFn).lastCalledWith({
     state: { myValue: 2 },
     setState: expect.any(Function),
+    resetState: expect.any(Function),
+  })
+
+  // Change initial, and update the whole tree
+  testRenderer.update(<State initial={{ myValue: 3 }} render={renderFn} />)
+
+  // Value hasn't been changed
+  expect(renderFn).lastCalledWith({
+    state: { myValue: 2 },
+    setState: expect.any(Function),
+    resetState: expect.any(Function),
+  })
+
+  // Reset state
+  lastCallArg(renderFn).resetState()
+
+  // Now state value is equal to initial
+  expect(renderFn).lastCalledWith({
+    state: { myValue: 3 },
+    setState: expect.any(Function),
+    resetState: expect.any(Function),
   })
 })
 

tests/test_flow.js

@@ -419,7 +419,7 @@ const noop = () => null
 
 /* State with inferred generic */
 {
-  const render = ({ state, setState }) => {
+  const render = ({ state, setState, resetState }) => {
     ;(state.v: number)
     setState({})
     setState({ v: 1 })
@@ -431,6 +431,12 @@ const noop = () => null
     setState({ t: 1 })
     // $FlowFixMe
     setState({ n: 2 })
+
+    resetState()
+    resetState(() => {})
+
+    // $FlowFixMe
+    resetState(1)
   }
   const onChange = state => {
     ;(state.v: number)