From df1aa5f490a17c93d444141375e6721949ce3656 Mon Sep 17 00:00:00 2001
From: Dave Smith <getdavemail@gmail.com>
Date: Mon, 21 Mar 2022 11:46:35 +0000
Subject: [PATCH] Selector and associated tests

---
 packages/block-editor/src/store/selectors.js  | 23 +++++++
 .../block-editor/src/store/test/selectors.js  | 63 +++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/packages/block-editor/src/store/selectors.js b/packages/block-editor/src/store/selectors.js
index 5a88b6fb09b0ae..d9b6f2e212bec5 100644
--- a/packages/block-editor/src/store/selectors.js
+++ b/packages/block-editor/src/store/selectors.js
@@ -278,6 +278,29 @@ export const getGlobalBlockCount = createSelector(
 	( state ) => [ state.blocks.order, state.blocks.byClientId ]
 );
 
+/**
+ * Returns all global blocks that match a blockName. Results include nested blocks.
+ *
+ * @param {Object}  state     Global application state.
+ * @param {?string} blockName Optional block name, if not specified, returns an empty array.
+ *
+ * @return {Array} Array of clientIds of blocks with name equal to blockName.
+ */
+export const __experimentalGetGlobalBlocksByName = createSelector(
+	( state, blockName ) => {
+		if ( ! blockName ) {
+			return EMPTY_ARRAY;
+		}
+		const clientIds = getClientIdsWithDescendants( state );
+		const foundBlocks = clientIds.filter( ( clientId ) => {
+			const block = state.blocks.byClientId[ clientId ];
+			return block.name === blockName;
+		} );
+		return foundBlocks.length > 0 ? foundBlocks : EMPTY_ARRAY;
+	},
+	( state ) => [ state.blocks.order, state.blocks.byClientId ]
+);
+
 /**
  * Given an array of block client IDs, returns the corresponding array of block
  * objects.
diff --git a/packages/block-editor/src/store/test/selectors.js b/packages/block-editor/src/store/test/selectors.js
index a9baaec53d3468..1a6d496df0e49c 100644
--- a/packages/block-editor/src/store/test/selectors.js
+++ b/packages/block-editor/src/store/test/selectors.js
@@ -77,6 +77,7 @@ const {
 	__unstableGetClientIdsTree,
 	__experimentalGetPatternTransformItems,
 	wasBlockJustInserted,
+	__experimentalGetGlobalBlocksByName,
 } = selectors;
 
 describe( 'selectors', () => {
@@ -797,6 +798,68 @@ describe( 'selectors', () => {
 		} );
 	} );
 
+	describe( '__experimentalGetGlobalBlocksByName', () => {
+		const state = {
+			blocks: {
+				byClientId: {
+					123: { clientId: 123, name: 'core/heading' },
+					456: { clientId: 456, name: 'core/paragraph' },
+					789: { clientId: 789, name: 'core/paragraph' },
+					1011: { clientId: 1011, name: 'core/group' },
+					1213: { clientId: 1213, name: 'core/paragraph' },
+					1415: { clientId: 1213, name: 'core/paragraph' },
+				},
+				attributes: {
+					123: {},
+					456: {},
+					789: {},
+					1011: {},
+					1213: {},
+					1415: {},
+				},
+				order: {
+					'': [ 123, 456, 1011 ],
+					1011: [ 1415, 1213 ],
+				},
+				parents: {
+					123: '',
+					456: '',
+					1011: '',
+					1213: 1011,
+					1415: 1011,
+				},
+			},
+		};
+
+		it( 'should return the clientIds of blocks of a given type', () => {
+			expect(
+				__experimentalGetGlobalBlocksByName( state, 'core/heading' )
+			).toStrictEqual( [ 123 ] );
+		} );
+
+		it( 'should return the clientIds of blocks of a given type even if blocks are nested', () => {
+			expect(
+				__experimentalGetGlobalBlocksByName( state, 'core/paragraph' )
+			).toStrictEqual( [ 456, 1415, 1213 ] );
+		} );
+
+		it( 'Should return empty array if no blocks match. The empty array should be the same reference', () => {
+			const result = __experimentalGetGlobalBlocksByName(
+				state,
+				'test/missing'
+			);
+			expect(
+				__experimentalGetGlobalBlocksByName( state, 'test/missing' )
+			).toStrictEqual( [] );
+			expect(
+				__experimentalGetGlobalBlocksByName(
+					state,
+					'test/missing2'
+				) === result
+			).toBe( true );
+		} );
+	} );
+
 	describe( 'getSelectedBlockClientId', () => {
 		it( 'should return null if no block is selected', () => {
 			const state = {