History: Batch title and text editor edit undo history

editor/actions.js

@@ -227,10 +227,24 @@ export function clearBlockInsertionPoint() {
 	};
 }
 
-export function editPost( edits ) {
+/**
+ * Returns an action object used in signalling that the post has been edited.
+ *
+ * @param  {Object}  edits   Key-value pairs of edited post attributes
+ * @param  {?Object} options Optional object of options, currently supporting
+ *                           batch flag (for grouping sequential edits)
+ * @return {Object}          Action object
+ */
+export function editPost( edits, options ) {
+	let meta;
+	if ( options && options.batch ) {
+		meta = { batchHistory: true };
+	}
+
 	return {
 		type: 'EDIT_POST',
 		edits,
+		meta,
 	};
 }
 

editor/components/post-text-editor/index.js

@@ -65,7 +65,7 @@ export default connect(
 	} ),
 	{
 		onChange( content ) {
-			return editPost( { content } );
+			return editPost( { content }, { batch: true } );
 		},
 		onPersist( content ) {
 			return resetBlocks( parse( content ) );

editor/components/post-title/index.js

@@ -136,7 +136,7 @@ export default connect(
 			return insertBlock( createBlock( getDefaultBlockName() ), 0 );
 		},
 		onUpdate( title ) {
-			return editPost( { title } );
+			return editPost( { title }, { batch: true } );
 		},
 		clearSelectedBlock,
 	}

editor/utils/with-history/index.js

@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { includes } from 'lodash';
+import { includes, get } from 'lodash';
 
 /**
  * Reducer enhancer which transforms the result of the original reducer into an
@@ -19,6 +19,8 @@ export default function withHistory( reducer, options = {} ) {
 		future: [],
 	};
 
+	let isBatching = false;
+
 	return ( state = initialState, action ) => {
 		const { past, present, future } = state;
 
@@ -62,8 +64,22 @@ export default function withHistory( reducer, options = {} ) {
 			return state;
 		}
 
+		const nextPast = [ ...past, present ];
+
+		// If batching, prevent accumulating past until the next action which
+		// doesn't include the batch flag.
+		if ( get( action.meta, 'batchHistory' ) ) {
+			if ( isBatching ) {
+				nextPast.splice( -1, 1 );
+			}
+
+			isBatching = true;
+		} else {
+			isBatching = false;
+		}
+
 		return {
-			past: [ ...past, present ],
+			past: nextPast,
 			present: nextPresent,
 			future: [],
 		};

editor/utils/with-history/test/index.js

@@ -118,4 +118,53 @@ describe( 'withHistory', () => {
 
 		expect( state ).toBe( original );
 	} );
+
+	it( 'should allow history batching', () => {
+		const reducer = withHistory( counter );
+
+		let state;
+		state = reducer( undefined, {} );
+
+		state = reducer( state, { type: 'INCREMENT', meta: { batchHistory: true } } );
+		expect( state ).toEqual( {
+			past: [ 0 ],
+			present: 1,
+			future: [],
+		} );
+
+		state = reducer( state, { type: 'INCREMENT', meta: { batchHistory: true } } );
+		expect( state ).toEqual( {
+			past: [ 0 ],
+			present: 2,
+			future: [],
+		} );
+
+		state = reducer( state, { type: 'INCREMENT' } );
+		expect( state ).toEqual( {
+			past: [ 0, 2 ],
+			present: 3,
+			future: [],
+		} );
+
+		state = reducer( state, { type: 'INCREMENT', meta: { batchHistory: true } } );
+		expect( state ).toEqual( {
+			past: [ 0, 2, 3 ],
+			present: 4,
+			future: [],
+		} );
+
+		state = reducer( state, { type: 'INCREMENT', meta: { batchHistory: true } } );
+		expect( state ).toEqual( {
+			past: [ 0, 2, 3 ],
+			present: 5,
+			future: [],
+		} );
+
+		state = reducer( state, { type: 'UNDO' } );
+		expect( state ).toEqual( {
+			past: [ 0, 2 ],
+			present: 3,
+			future: [ 5 ],
+		} );
+	} );
 } );