Use apiFetch instead of window.fetch (#50043)

* Use apiFetch instead of window.fetch

* add comment

* Fix mocking in test

---------

Co-authored-by: scruffian <ben@scruffian.com>
Co-authored-by: Dave Smith <getdavemail@gmail.com>

packages/core-data/src/resolvers.js

@@ -409,15 +409,15 @@ export const getAutosave =
 export const __experimentalGetTemplateForLink =
 	( link ) =>
 	async ( { dispatch, resolveSelect } ) => {
-		// Ideally this should be using an apiFetch call
-		// We could potentially do so by adding a "filter" to the `wp_template` end point.
-		// Also it seems the returned object is not a regular REST API post type.
 		let template;
 		try {
-			template = await window
-				.fetch( addQueryArgs( link, { '_wp-find-template': true } ) )
-				.then( ( res ) => res.json() )
-				.then( ( { data } ) => data );
+			// This is NOT calling a REST endpoint but rather ends up with a response from
+			// an Ajax function which has a different shape from a WP_REST_Response.
+			template = await apiFetch( {
+				url: addQueryArgs( link, {
+					'_wp-find-template': true,
+				} ),
+			} ).then( ( { data } ) => data );
 		} catch ( e ) {
 			// For non-FSE themes, it is possible that this request returns an error.
 		}

packages/edit-site/src/store/test/actions.js

@@ -168,21 +168,13 @@ describe( 'actions', () => {
 			const ID = 'emptytheme//single';
 			const SLUG = 'single';
 
-			window.fetch = async ( path ) => {
-				if ( path === '/?_wp-find-template=true' ) {
-					return {
-						json: async () => ( { data: { id: ID, slug: SLUG } } ),
-					};
-				}
-
-				throw {
-					code: 'unknown_path',
-					message: `Unknown path: ${ path }`,
-				};
-			};
-
 			apiFetch.setFetchHandler( async ( options ) => {
-				const { method = 'GET', path } = options;
+				const { method = 'GET', path, url } = options;
+
+				// Called with url arg in `__experimentalGetTemplateForLink`
+				if ( url ) {
+					return { data: { id: ID, slug: SLUG } };
+				}
 
 				if ( method === 'GET' ) {
 					if ( path.startsWith( '/wp/v2/types' ) ) {