From a6b33bdbffed2e4cd8b7c507deecf7d25839d517 Mon Sep 17 00:00:00 2001
From: Riad Benguella <benguella@gmail.com>
Date: Mon, 11 Mar 2019 12:21:01 +0100
Subject: [PATCH] Support parent/child registries

---
 packages/data/src/registry.js      | 21 ++++++++++---
 packages/data/src/test/registry.js | 48 ++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/packages/data/src/registry.js b/packages/data/src/registry.js
index e1c324f6ef8ac0..15f02180c7b859 100644
--- a/packages/data/src/registry.js
+++ b/packages/data/src/registry.js
@@ -34,11 +34,12 @@ import createCoreDataStore from './store';
  * Creates a new store registry, given an optional object of initial store
  * configurations.
  *
- * @param {Object} storeConfigs Initial store configurations.
+ * @param {Object}  storeConfigs Initial store configurations.
+ * @param {Object?} parent       Parent registry.
  *
  * @return {WPDataRegistry} Data registry.
  */
-export function createRegistry( storeConfigs = {} ) {
+export function createRegistry( storeConfigs = {}, parent = null ) {
 	const stores = {};
 	let listeners = [];
 
@@ -74,7 +75,11 @@ export function createRegistry( storeConfigs = {} ) {
 	 */
 	function select( reducerKey ) {
 		const store = stores[ reducerKey ];
-		return store && store.getSelectors();
+		if ( store ) {
+			return store.getSelectors();
+		}
+
+		return parent && parent.select( reducerKey );
 	}
 
 	/**
@@ -87,7 +92,11 @@ export function createRegistry( storeConfigs = {} ) {
 	 */
 	function dispatch( reducerKey ) {
 		const store = stores[ reducerKey ];
-		return store && store.getActions();
+		if ( store ) {
+			return store.getActions();
+		}
+
+		return parent && parent.dispatch( reducerKey );
 	}
 
 	//
@@ -172,5 +181,9 @@ export function createRegistry( storeConfigs = {} ) {
 		( [ name, config ] ) => registry.registerStore( name, config )
 	);
 
+	if ( parent ) {
+		parent.subscribe( globalListener );
+	}
+
 	return withPlugins( registry );
 }
diff --git a/packages/data/src/test/registry.js b/packages/data/src/test/registry.js
index cd18ac2d892854..b828cd01991596 100644
--- a/packages/data/src/test/registry.js
+++ b/packages/data/src/test/registry.js
@@ -604,4 +604,52 @@ describe( 'createRegistry', () => {
 			expect( registry.select() ).toBe( 10 );
 		} );
 	} );
+
+	describe( 'parent registry', () => {
+		it( 'should call parent registry selectors/actions if defined', () => {
+			const mySelector = jest.fn();
+			const myAction = jest.fn();
+			const getSelectors = () => ( { mySelector } );
+			const getActions = () => ( { myAction } );
+			const subscribe = () => {};
+			registry.registerGenericStore( 'store', { getSelectors, getActions, subscribe } );
+			const subRegistry = createRegistry( {}, registry );
+
+			subRegistry.select( 'store' ).mySelector();
+			subRegistry.dispatch( 'store' ).myAction();
+
+			expect( mySelector ).toHaveBeenCalled();
+			expect( myAction ).toHaveBeenCalled();
+		} );
+
+		it( 'should override existing store in parent registry', () => {
+			const mySelector = jest.fn();
+			const myAction = jest.fn();
+			const getSelectors = () => ( { mySelector } );
+			const getActions = () => ( { myAction } );
+			const subscribe = () => {};
+			registry.registerGenericStore( 'store', { getSelectors, getActions, subscribe } );
+
+			const subRegistry = createRegistry( {}, registry );
+			const mySelector2 = jest.fn();
+			const myAction2 = jest.fn();
+			const getSelectors2 = () => ( { mySelector: mySelector2 } );
+			const getActions2 = () => ( { myAction: myAction2 } );
+			const subscribe2 = () => {};
+			subRegistry.registerGenericStore( 'store', {
+				getSelectors: getSelectors2,
+				getActions: getActions2,
+				subscribe: subscribe2,
+			} );
+
+			subRegistry.select( 'store' ).mySelector();
+			subRegistry.dispatch( 'store' ).myAction();
+
+			expect( mySelector ).not.toHaveBeenCalled();
+			expect( myAction ).not.toHaveBeenCalled();
+
+			expect( mySelector2 ).toHaveBeenCalled();
+			expect( myAction2 ).toHaveBeenCalled();
+		} );
+	} );
 } );