improve tests

- use native jest each api
- improve naming of variables
- simplify mocking and test setup.

packages/data/src/components/use-select/test/index.js

@@ -133,34 +133,35 @@ describe( 'useSelect', () => {
 		} );
 	} );
 	describe( 'rerenders as expected with various mapSelect return types', () => {
-		const getComponent = ( selectSpy ) => () => {
-			selectSpy.mockImplementation(
-				( select ) => select( 'testStore' ).testSelector()
-			);
-			const data = useSelect( selectSpy, [] );
+		const getComponent = ( mapSelectSpy ) => () => {
+			const data = useSelect( mapSelectSpy, [] );
 			return <div data={ data } />;
 		};
-		let selectorSpy,
-			subscribedSpy,
-			subscriberSpy,
-			selectSpy,
-			TestComponent;
+		let subscribedSpy, TestComponent;
+		const mapSelectSpy = jest.fn(
+			( select ) => select( 'testStore' ).testSelector()
+		);
+		const selectorSpy = jest.fn();
+		const subscribeCallback = ( subscription ) => {
+			subscribedSpy = subscription;
+		};
+
 		beforeEach( () => {
-			selectorSpy = jest.fn();
-			subscriberSpy = ( subscription ) => {
-				subscribedSpy = subscription;
-			};
 			registry.registerStore( 'testStore', {
 				reducer: () => null,
 				selectors: {
 					testSelector: selectorSpy,
 				},
 			} );
-			registry.subscribe = subscriberSpy;
-			selectSpy = jest.fn();
-			TestComponent = getComponent( selectSpy );
+			registry.subscribe = subscribeCallback;
+			TestComponent = getComponent( mapSelectSpy );
+		} );
+		afterEach( () => {
+			selectorSpy.mockClear();
+			mapSelectSpy.mockClear();
 		} );
-		[
+
+		it.each( [
 			[
 				'boolean',
 				[ false, true ],
@@ -189,34 +190,33 @@ describe( 'useSelect', () => {
 				'undefined',
 				[ undefined, 42 ],
 			],
-		].forEach(
-			( [ type, testValues ] ) => {
-				const [ valueA, valueB ] = testValues;
-				it( `renders as expected with ${ type } return values`, () => {
-					selectorSpy.mockReturnValue( valueA );
-					let renderer;
-					act( () => {
-						renderer = TestRenderer.create(
-							<RegistryProvider value={ registry }>
-								<TestComponent />
-							</RegistryProvider>
-						);
-					} );
-					const testInstance = renderer.root;
-					// ensure expected state was rendered.
-					expect( testInstance.findByType( 'div' ).props.data ).toEqual( valueA );
-
-					// Update the returned value from the selector and trigger the
-					// subscription which should in turn trigger a re-render.
-					act( () => {
-						selectorSpy.mockReturnValue( valueB );
-						subscribedSpy();
-					} );
-					expect( testInstance.findByType( 'div' ).props.data ).toEqual( valueB );
-					expect( selectSpy ).toHaveBeenCalledTimes( 3 );
-				} );
-			}
-		);
+		] )( 'renders as expected with %s return values', (
+			type,
+			testValues,
+		) => {
+			const [ valueA, valueB ] = testValues;
+			selectorSpy.mockReturnValue( valueA );
+			let renderer;
+			act( () => {
+				renderer = TestRenderer.create(
+					<RegistryProvider value={ registry }>
+						<TestComponent />
+					</RegistryProvider>
+				);
+			} );
+			const testInstance = renderer.root;
+			// ensure expected state was rendered.
+			expect( testInstance.findByType( 'div' ).props.data ).toEqual( valueA );
+
+			// Update the returned value from the selector and trigger the
+			// subscription which should in turn trigger a re-render.
+			act( () => {
+				selectorSpy.mockReturnValue( valueB );
+				subscribedSpy();
+			} );
+			expect( testInstance.findByType( 'div' ).props.data ).toEqual( valueB );
+			expect( mapSelectSpy ).toHaveBeenCalledTimes( 3 );
+		} );
 	} );
 } );