test: adds unit tests for <Engines /> component (#92)

src/components/Engines/Engines.test.tsx

@@ -0,0 +1,66 @@
+import React from 'react';
+import { shallow } from 'enzyme';
+
+jest.mock('./img/node.png', () => '');
+jest.mock('../Install/img/npm.svg', () => '');
+
+describe('<Engines /> component', () => {
+  beforeEach(() => {
+    jest.resetModules();
+  });
+
+  test('should render the component in default state', () => {
+    const packageMeta = {
+      latest: {
+        engines: {
+          node: '>= 0.1.98',
+          npm: '>3',
+        },
+      },
+    };
+
+    jest.doMock('../../pages/version/Version', () => ({
+      DetailContextConsumer: component => {
+        return component.children({ packageMeta });
+      },
+    }));
+
+    const Engines = require('./Engines').default;
+    const wrapper = shallow(<Engines />);
+    expect(wrapper.html()).toMatchSnapshot();
+  });
+
+  test('should render the component when there is no engine key in package meta', () => {
+    const packageMeta = {
+      latest: {},
+    };
+
+    jest.doMock('../../pages/version/Version', () => ({
+      DetailContextConsumer: component => {
+        return component.children({ packageMeta });
+      },
+    }));
+
+    const Engines = require('./Engines').default;
+    const wrapper = shallow(<Engines />);
+    expect(wrapper.html()).toEqual('');
+  });
+
+  test('should render the component when there is no keys in engine in package meta', () => {
+    const packageMeta = {
+      latest: {
+        engines: {},
+      },
+    };
+
+    jest.doMock('../../pages/version/Version', () => ({
+      DetailContextConsumer: component => {
+        return component.children({ packageMeta });
+      },
+    }));
+
+    const Engines = require('./Engines').default;
+    const wrapper = shallow(<Engines />);
+    expect(wrapper.html()).toEqual('');
+  });
+});