From 4edd1d0fcd311101e2db359992384a231fbe88cb Mon Sep 17 00:00:00 2001
From: Andrew Duthie <andrew@andrewduthie.com>
Date: Sat, 20 Jul 2019 11:54:38 +0200
Subject: [PATCH] Data: Create registry selector with self-contained registry
 proxying

---
 packages/data/src/factory.js               | 25 +++++++++++++++--
 packages/data/src/namespace-store/index.js | 17 +++---------
 packages/data/src/test/registry.js         | 32 ++++++++++++++++++++++
 3 files changed, 59 insertions(+), 15 deletions(-)

diff --git a/packages/data/src/factory.js b/packages/data/src/factory.js
index f7dbb7f269a869..e734d41f1a4c6c 100644
--- a/packages/data/src/factory.js
+++ b/packages/data/src/factory.js
@@ -1,3 +1,8 @@
+/**
+ * Internal dependencies
+ */
+import defaultRegistry from './default-registry';
+
 /**
  * Mark a selector as a registry selector.
  *
@@ -6,9 +11,25 @@
  * @return {function} marked registry selector.
  */
 export function createRegistrySelector( registrySelector ) {
-	registrySelector.isRegistrySelector = true;
+	const selector = ( ...args ) => registrySelector( selector.registry.select )( ...args );
+
+	/**
+	 * Flag indicating to selector registration mapping that the selector should
+	 * be mapped as a registry selector.
+	 *
+	 * @type {boolean}
+	 */
+	selector.isRegistrySelector = true;
+
+	/**
+	 * Registry on which to call `select`, stubbed for non-standard usage to
+	 * use the default registry.
+	 *
+	 * @type {WPDataRegistry}
+	 */
+	selector.registry = defaultRegistry;
 
-	return registrySelector;
+	return selector;
 }
 
 /**
diff --git a/packages/data/src/namespace-store/index.js b/packages/data/src/namespace-store/index.js
index 6c8d7d94094eba..16c3d288ce94a1 100644
--- a/packages/data/src/namespace-store/index.js
+++ b/packages/data/src/namespace-store/index.js
@@ -45,16 +45,12 @@ export default function createNamespace( key, options, registry ) {
 		...mapValues( metadataSelectors, ( selector ) => ( state, ...args ) => selector( state.metadata, ...args ) ),
 		...mapValues( options.selectors, ( selector ) => {
 			if ( selector.isRegistrySelector ) {
-				const mappedSelector = ( reg ) => ( state, ...args ) => {
-					return selector( reg )( state.root, ...args );
-				};
-				mappedSelector.isRegistrySelector = selector.isRegistrySelector;
-				return mappedSelector;
+				selector.registry = registry;
 			}
 
 			return ( state, ...args ) => selector( state.root, ...args );
 		} ),
-	}, store, registry );
+	}, store );
 	if ( options.resolvers ) {
 		const result = mapResolvers( options.resolvers, selectors, store );
 		resolvers = result.resolvers;
@@ -149,16 +145,11 @@ function createReduxStore( key, options, registry ) {
  *                            public facing API. Selectors will get passed the
  *                            state as first argument.
  * @param {Object} store      The redux store to which the selectors should be mapped.
- * @param {Object} registry   Registry reference.
  *
  * @return {Object}           Selectors mapped to the redux store provided.
  */
-function mapSelectors( selectors, store, registry ) {
-	const createStateSelector = ( registeredSelector ) => {
-		const registrySelector = registeredSelector.isRegistrySelector ?
-			registeredSelector( registry.select ) :
-			registeredSelector;
-
+function mapSelectors( selectors, store ) {
+	const createStateSelector = ( registrySelector ) => {
 		const selector = function runSelector() {
 			// This function is an optimized implementation of:
 			//
diff --git a/packages/data/src/test/registry.js b/packages/data/src/test/registry.js
index 57b8789e7095c3..23a6d399ce7786 100644
--- a/packages/data/src/test/registry.js
+++ b/packages/data/src/test/registry.js
@@ -464,6 +464,38 @@ describe( 'createRegistry', () => {
 
 			expect( registry.select( 'reducer2' ).selector2() ).toEqual( 'result1' );
 		} );
+
+		it( 'should run the registry selector from a non-registry selector', () => {
+			const selector1 = () => 'result1';
+			const selector2 = createRegistrySelector( ( select ) => () =>
+				select( 'reducer1' ).selector1()
+			);
+			const selector3 = () => selector2();
+			registry.registerStore( 'reducer1', {
+				reducer: () => 'state1',
+				selectors: {
+					selector1,
+				},
+			} );
+			registry.registerStore( 'reducer2', {
+				reducer: () => 'state1',
+				selectors: {
+					selector2,
+					selector3,
+				},
+			} );
+
+			expect( registry.select( 'reducer2' ).selector3() ).toEqual( 'result1' );
+		} );
+
+		it( 'gracefully stubs select on selector calls', () => {
+			const selector = createRegistrySelector( ( select ) => () => select );
+
+			const maybeSelect = selector();
+
+			expect( maybeSelect ).toEqual( expect.any( Function ) );
+			expect( maybeSelect() ).toEqual( expect.any( Object ) );
+		} );
 	} );
 
 	describe( 'subscribe', () => {