Update Modal's mock to not render its children when it is not visible

Libraries/Modal/__tests__/Modal-test.js

@@ -27,6 +27,15 @@ describe('<Modal />', () => {
     expect(instance).toMatchSnapshot();
   });
 
+  it('should not render its children when mocked with visible=false', () => {
+    const instance = render.create(
+      <Modal visible={false}>
+        <View />
+      </Modal>,
+    );
+    expect(instance).toMatchSnapshot();
+  });
+
   it('should shallow render as <Modal> when mocked', () => {
     const output = render.shallow(
       <Modal>

Libraries/Modal/__tests__/__snapshots__/Modal-test.js.snap

@@ -1,5 +1,12 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`<Modal /> should not render its children when mocked with visible=false 1`] = `
+<Modal
+  hardwareAccelerated={false}
+  visible={false}
+/>
+`;
+
 exports[`<Modal /> should render as <Modal> when mocked 1`] = `
 <Modal
   hardwareAccelerated={false}
@@ -13,7 +20,7 @@ exports[`<Modal /> should render as <RCTModalHostView> when not mocked 1`] = `
 <RCTModalHostView
   animationType="none"
   hardwareAccelerated={false}
-  identifier={1}
+  identifier={4}
   onDismiss={[Function]}
   onStartShouldSetResponder={[Function]}
   presentationStyle="fullScreen"

jest/mockModal.js

@@ -0,0 +1,32 @@
+/**
+ * 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
+ * @flow strict-local
+ */
+
+/* eslint-env jest */
+
+'use strict';
+
+const React = require('react');
+const Modal = require('../Libraries/Modal/Modal');
+
+function mockModal(BaseComponent: $FlowFixMe) {
+  class ModalMock extends BaseComponent {
+    render(): React.Element<typeof Modal> {
+      return (
+        <BaseComponent
+          {...this.props}
+          children={this.props.visible !== true ? null : this.props.children}
+        />
+      );
+    }
+  }
+  return ModalMock;
+}
+
+module.exports = (mockModal: $FlowFixMe);

jest/setup.js

@@ -110,9 +110,11 @@ jest
       getNativeRef: jest.fn(),
     }),
   )
-  .mock('../Libraries/Modal/Modal', () =>
-    mockComponent('../Libraries/Modal/Modal'),
-  )
+  .mock('../Libraries/Modal/Modal', () => {
+    const baseComponent = mockComponent('../Libraries/Modal/Modal');
+    const mockModal = jest.requireActual('./mockModal');
+    return mockModal(baseComponent);
+  })
   .mock('../Libraries/Components/View/View', () =>
     mockComponent('../Libraries/Components/View/View', MockNativeMethods),
   )