Stats: align statsVideo normalizer with #112499 to avoid merge conflicts

Adopts the identical normalizer hunk and tests from the video details
modernization branch (Array.isArray guard on payload.data and the
attachment post passthrough) so whichever PR lands second merges
cleanly.

Author: Nikschavan

client/state/stats/lists/test/utils.js

@@ -1636,6 +1636,30 @@ describe( 'utils', () => {
 				expect( normalizers.statsVideo() ).toBeNull();
 			} );
 
+			test( 'should return empty data when the endpoint reports an empty window', () => {
+				// With no rows in the requested window, the endpoint returns a
+				// single object instead of the usual [ date, value ] tuples.
+				expect(
+					normalizers.statsVideo( {
+						data: { date: '7-10', p: '0' },
+						pages: [],
+					} )
+				).toEqual( { pages: [], data: [], post: null } );
+			} );
+
+			test( 'should skip non-tuple entries in the data array', () => {
+				expect(
+					normalizers.statsVideo( {
+						data: [ [ '2016-11-12', 1 ], { date: '7-10', p: '0' } ],
+						pages: [],
+					} )
+				).toEqual( {
+					pages: [],
+					data: [ { period: '2016-11-12', value: 1 } ],
+					post: null,
+				} );
+			} );
+
 			test( 'should return a properly parsed data array', () => {
 				expect(
 					normalizers.statsVideo( {
@@ -1675,23 +1699,20 @@ describe( 'utils', () => {
 							link: 'http://www.themepremium.com/blog-with-the-speed-of-your-thought-with-the-p2-theme/',
 						},
 					],
+					post: null,
 				} );
 			} );
 
-			test( 'should drop the stub object row returned for videos with no plays', () => {
-				expect(
-					normalizers.statsVideo( {
-						data: [ { date: '7-10', p: '0' } ],
-						pages: [ 'https://vip.wordpress.com/category/themes/' ],
-					} )
-				).toEqual( {
+			test( 'should pass through the attachment post', () => {
+				const post = {
+					ID: 43948,
+					post_title: 'blank-canvas-split-screen',
+					post_date: '2021-02-08 13:53:37',
+				};
+				expect( normalizers.statsVideo( { data: [], pages: [], post } ) ).toEqual( {
+					pages: [],
 					data: [],
-					pages: [
-						{
-							label: 'https://vip.wordpress.com/category/themes/',
-							link: 'https://vip.wordpress.com/category/themes/',
-						},
-					],
+					post,
 				} );
 			} );
 		} );

client/state/stats/lists/utils.js

@@ -834,9 +834,9 @@ export const normalizers = {
 		}
 
 		let data = [];
-		if ( payload.data ) {
-			// When a video has no plays for the period, the API returns a stub object
-			// (e.g. `{ date: '7-10', p: '0' }`) instead of a `[ period, value ]` pair.
+		// When the requested window has no rows at all, the endpoint returns a single
+		// `{ date, p }` object instead of the usual `[ date, value ]` tuples.
+		if ( Array.isArray( payload.data ) ) {
 			data = payload.data
 				.filter( ( item ) => Array.isArray( item ) )
 				.map( ( item ) => {
@@ -854,7 +854,9 @@ export const normalizers = {
 			} );
 		}
 
-		return { pages, data };
+		// The endpoint also returns the video's attachment post, which carries
+		// the title and upload date.
+		return { pages, data, post: payload.post ?? null };
 	},
 
 	/**