fix setstate order (#3763)

src/diff/index.js

@@ -96,6 +96,7 @@ export function diff(
 			if (c._nextState == null) {
 				c._nextState = c.state;
 			}
+
 			if (newType.getDerivedStateFromProps != null) {
 				if (c._nextState == c.state) {
 					c._nextState = assign({}, c._nextState);
@@ -110,11 +111,6 @@ export function diff(
 			oldProps = c.props;
 			oldState = c.state;
 
-			for (tmp = 0; tmp < c._stateCallbacks.length; tmp++) {
-				c._renderCallbacks.push(c._stateCallbacks[tmp]);
-				c._stateCallbacks = [];
-			}
-
 			// Invoke pre-render lifecycle methods
 			if (isNew) {
 				if (
@@ -156,6 +152,12 @@ export function diff(
 					newVNode._children.forEach(vnode => {
 						if (vnode) vnode._parent = newVNode;
 					});
+
+					for (let i = 0; i < c._stateCallbacks.length; i++) {
+						c._renderCallbacks.push(c._stateCallbacks[i]);
+					}
+					c._stateCallbacks = [];
+
 					if (c._renderCallbacks.length) {
 						commitQueue.push(c);
 					}
@@ -188,6 +190,11 @@ export function diff(
 				if (renderHook) renderHook(newVNode);
 
 				tmp = c.render(c.props, c.state, c.context);
+
+				for (let i = 0; i < c._stateCallbacks.length; i++) {
+					c._renderCallbacks.push(c._stateCallbacks[i]);
+				}
+				c._stateCallbacks = [];
 			} else {
 				do {
 					c._dirty = false;
@@ -524,7 +531,11 @@ export function unmount(vnode, parentVNode, skipRemove) {
 	if ((r = vnode._children)) {
 		for (let i = 0; i < r.length; i++) {
 			if (r[i]) {
-				unmount(r[i], parentVNode, skipRemove || typeof vnode.type !== 'function');
+				unmount(
+					r[i],
+					parentVNode,
+					skipRemove || typeof vnode.type !== 'function'
+				);
 			}
 		}
 	}

test/browser/lifecycles/componentDidMount.test.js

@@ -1,14 +1,17 @@
 import { createElement, render, Component } from 'preact';
+import { setupRerender } from 'preact/test-utils';
 import { setupScratch, teardown } from '../../_util/helpers';
 
 /** @jsx createElement */
 
 describe('Lifecycle methods', () => {
 	/** @type {HTMLDivElement} */
 	let scratch;
+	let rerender;
 
 	beforeEach(() => {
 		scratch = setupScratch();
+		rerender = setupRerender();
 	});
 
 	afterEach(() => {
@@ -32,5 +35,32 @@ describe('Lifecycle methods', () => {
 			render(<App />, scratch);
 			expect(spy).to.have.been.calledOnceWith(scratch.firstChild);
 		});
+
+		it('supports multiple setState callbacks', () => {
+			const spy = sinon.spy();
+
+			class App extends Component {
+				constructor(props) {
+					super(props);
+					this.state = { count: 0 };
+				}
+
+				componentDidMount() {
+					// eslint-disable-next-line
+					this.setState({ count: 1 }, spy);
+					// eslint-disable-next-line
+					this.setState({ count: 2 }, spy);
+				}
+
+				render() {
+					return <div />;
+				}
+			}
+
+			render(<App />, scratch);
+
+			rerender();
+			expect(spy).to.have.been.calledTwice;
+		});
 	});
 });

test/browser/lifecycles/lifecycle.test.js

@@ -155,8 +155,8 @@ describe('Lifecycle methods', () => {
 			'inner render',
 			'inner getSnapshotBeforeUpdate',
 			'inner componentDidUpdate',
-			'outer setState callback',
-			'outer componentDidUpdate'
+			'outer componentDidUpdate',
+			'outer setState callback'
 		]);
 
 		// Inner state update
@@ -168,8 +168,8 @@ describe('Lifecycle methods', () => {
 			'inner shouldComponentUpdate',
 			'inner render',
 			'inner getSnapshotBeforeUpdate',
-			'inner setState callback',
-			'inner componentDidUpdate'
+			'inner componentDidUpdate',
+			'inner setState callback'
 		]);
 
 		// Force update Outer