Add tests for codegenNativeComponent

Summary: Adds tests for codegenNativeComponent

Reviewed By: TheSavior

Differential Revision: D16582627

fbshipit-source-id: 3527126c7838f3e2c0c56b19956c618f0a7fb9f9

Libraries/Utilities/__tests__/codegenNativeComponent-test.js

@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @emails oncall+react_native
+ */
+
+'use strict';
+
+const codegenNativeComponent = require('../codegenNativeComponent').default;
+const {UIManager} = require('react-native');
+
+// We need to unmock requireNativeComponent since it's under test.
+// Instead, we mock the function it calls, createReactNativeComponentClass,
+// so that we don't run into issues populating the registry with the same
+// component names.
+jest.unmock('../../ReactNative/requireNativeComponent');
+jest.mock(
+  '../../Renderer/shims/createReactNativeComponentClass',
+  () => componentName => componentName,
+);
+jest
+  .spyOn(UIManager, 'getViewManagerConfig')
+  .mockImplementation(componentName =>
+    componentName.includes('ComponentNameDoesNotExist') ? false : true,
+  );
+
+describe('codegenNativeComponent', () => {
+  it('should require component as is ', () => {
+    const component = codegenNativeComponent('ComponentName');
+    expect(component).toBe('ComponentName');
+  });
+
+  it('should require paperComponentName', () => {
+    const component = codegenNativeComponent('ComponentName', {
+      paperComponentName: 'PaperComponentName',
+    });
+    expect(component).toBe('PaperComponentName');
+  });
+
+  it('should fall back to requiring the deprecated paper component name', () => {
+    const component = codegenNativeComponent('ComponentNameDoesNotExist', {
+      paperComponentNameDeprecated: 'ComponentName',
+    });
+    expect(component).toBe('ComponentName');
+  });
+
+  it('should require the new component name', () => {
+    const component = codegenNativeComponent('ComponentName', {
+      paperComponentNameDeprecated: 'ComponentNameDoesNotExist',
+    });
+    expect(component).toBe('ComponentName');
+  });
+
+  it('should throw if neither component names exist', () => {
+    expect(() =>
+      codegenNativeComponent('ComponentNameDoesNotExistOne', {
+        paperComponentNameDeprecated: 'ComponentNameDoesNotExistTwo',
+      }),
+    ).toThrow(
+      'Failed to find native component for either ComponentNameDoesNotExistOne or ComponentNameDoesNotExistTwo',
+    );
+  });
+});