这里是解决方案，没有必要设置jest配置。
index.ts：

import React from 'react';
import './Translate';

interface ISomeComponentProps {
  title: string;
}

class SomeComponent extends React.Component<ISomeComponentProps> {
  public render() {
    const title = (global as any).Translator.trans(this.props.title);
    return <div>title: {title}</div>;
  }
}

export { SomeComponent };

Translate.ts：

const Translator = {
  trans: text => text
};

(global as any).Translator = Translator;

export { Translator };

单元测试：

import React from 'react';
import { shallow } from 'enzyme';
import { SomeComponent } from './';

(global as any).Translator.trans = jest.fn();

describe('SomeComponent', () => {
  it('t1', () => {
    const mockTitle = 'test title';
    (global as any).Translator.trans.mockReturnValueOnce(mockTitle);
    const wrapper = shallow(<SomeComponent title={mockTitle} />);
    expect(wrapper.text()).toBe(`title: ${mockTitle}`);
    expect((global as any).Translator.trans).toBeCalledWith(mockTitle);
  });
});

包含覆盖率报告的单元测试结果：

PASS  src/stackoverflow/47412169/index.spec.tsx
  SomeComponent
    ✓ t1 (14ms)

--------------|----------|----------|----------|----------|-------------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------|----------|----------|----------|----------|-------------------|
All files     |    92.31 |      100 |    66.67 |    91.67 |                   |
 Translate.ts |       75 |      100 |        0 |       75 |                 2 |
 index.tsx    |      100 |      100 |      100 |      100 |                   |
--------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        3.799s, estimated 6s

以下是完整的演示：https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/47412169

这里有一种方法可以在Jest中全局模拟变量/函数：
mockTranslate.js

// Globally mock gettext
global.gettext = jest.fn((text) => text);
global.pgettext = jest.fn((context, text) => text);

然后在您的jest.config.js中将其包含在setupFiles中：

const config = {
 // other configs
};

// HERE
config.setupFiles = ['./mockTranslate.js'];

module.exports = config;