From 5565d5cc2534d8a0a573d9073f616decefe54f0b Mon Sep 17 00:00:00 2001
From: Darren Ethier <darren@roughsmootheng.in>
Date: Sat, 25 May 2019 13:20:39 -0400
Subject: [PATCH] add new hook tests

---
 .../src/components/use-select/test/index.js   | 136 ++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 packages/data/src/components/use-select/test/index.js

diff --git a/packages/data/src/components/use-select/test/index.js b/packages/data/src/components/use-select/test/index.js
new file mode 100644
index 00000000000000..ce8d15f3aa0707
--- /dev/null
+++ b/packages/data/src/components/use-select/test/index.js
@@ -0,0 +1,136 @@
+/**
+ * External dependencies
+ */
+import TestRenderer, { act } from 'react-test-renderer';
+
+/**
+ * Internal dependencies
+ */
+import { createRegistry } from '../../../registry';
+import { RegistryProvider } from '../../registry-provider';
+import useSelect from '../index';
+
+describe( 'useSelect', () => {
+	let registry;
+	beforeEach( () => {
+		registry = createRegistry();
+	} );
+
+	const getTestComponent = ( mapSelectSpy, dependencyKey ) => ( props ) => {
+		const dependencies = props[ dependencyKey ];
+		mapSelectSpy.mockImplementation(
+			( select ) => ( {
+				results: select( 'testStore' ).testSelector( props.keyName ),
+			} )
+		);
+		const data = useSelect( mapSelectSpy, [ dependencies ] );
+		return <div>{ data.results }</div>;
+	};
+
+	it( 'passes the relevant data to the component', () => {
+		registry.registerStore( 'testStore', {
+			reducer: () => ( { foo: 'bar' } ),
+			selectors: {
+				testSelector: ( state, key ) => state[ key ],
+			},
+		} );
+		const selectSpy = jest.fn();
+		const TestComponent = jest.fn().mockImplementation(
+			getTestComponent( selectSpy, 'keyName' )
+		);
+		let renderer;
+		act( () => {
+			renderer = TestRenderer.create(
+				<RegistryProvider value={ registry }>
+					<TestComponent keyName="foo" />
+				</RegistryProvider>
+			);
+		} );
+		const testInstance = renderer.root;
+		// 2 times expected
+		// - 1 for initial mount
+		// - 1 for after mount before subscription set.
+		expect( selectSpy ).toHaveBeenCalledTimes( 2 );
+		expect( TestComponent ).toHaveBeenCalledTimes( 1 );
+
+		// ensure expected state was rendered
+		expect( testInstance.findByType( 'div' ).props ).toEqual( {
+			children: 'bar',
+		} );
+	} );
+
+	it( 'uses memoized selector if dependencies do not change', () => {
+		registry.registerStore( 'testStore', {
+			reducer: () => ( { foo: 'bar' } ),
+			selectors: {
+				testSelector: ( state, key ) => state[ key ],
+			},
+		} );
+
+		const selectSpyFoo = jest.fn().mockImplementation( () => 'foo' );
+		const selectSpyBar = jest.fn().mockImplementation( () => 'bar' );
+		const TestComponent = jest.fn().mockImplementation(
+			( props ) => {
+				const mapSelect = props.change ? selectSpyFoo : selectSpyBar;
+				const data = useSelect( mapSelect, [ props.keyName ] );
+				return <div>{ data }</div>;
+			}
+		);
+		let renderer;
+		act( () => {
+			renderer = TestRenderer.create(
+				<RegistryProvider value={ registry }>
+					<TestComponent keyName="foo" change={ true } />
+				</RegistryProvider>
+			);
+		} );
+		const testInstance = renderer.root;
+
+		expect( selectSpyFoo ).toHaveBeenCalledTimes( 2 );
+		expect( selectSpyBar ).toHaveBeenCalledTimes( 0 );
+		expect( TestComponent ).toHaveBeenCalledTimes( 1 );
+
+		// ensure expected state was rendered
+		expect( testInstance.findByType( 'div' ).props ).toEqual( {
+			children: 'foo',
+		} );
+
+		//rerender with non dependency changed
+		act( () => {
+			renderer.update(
+				<RegistryProvider value={ registry }>
+					<TestComponent keyName="foo" change={ false } />
+				</RegistryProvider>
+			);
+		} );
+
+		expect( selectSpyFoo ).toHaveBeenCalledTimes( 2 );
+		expect( selectSpyBar ).toHaveBeenCalledTimes( 0 );
+		expect( TestComponent ).toHaveBeenCalledTimes( 2 );
+
+		// ensure expected state was rendered
+		expect( testInstance.findByType( 'div' ).props ).toEqual( {
+			children: 'foo',
+		} );
+
+		// rerender with dependency changed
+		// rerender with non dependency changed
+		act( () => {
+			renderer.update(
+				<RegistryProvider value={ registry }>
+					<TestComponent keyName="bar" change={ false } />
+				</RegistryProvider>
+			);
+		} );
+
+		expect( selectSpyFoo ).toHaveBeenCalledTimes( 2 );
+		expect( selectSpyBar ).toHaveBeenCalledTimes( 1 );
+		expect( TestComponent ).toHaveBeenCalledTimes( 3 );
+
+		// ensure expected state was rendered
+		expect( testInstance.findByType( 'div' ).props ).toEqual( {
+			children: 'bar',
+		} );
+	} );
+} );
+