TS auto mock
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Installation

To make this library work you need to apply the ts-auto-mock transformer at compile time.

Unfortunately, TypeScript itself does not currently provide any easy way to use custom transformers out of the box.

See this TypeScript issue.

There are different ways to do this depending on how you are currently compiling your TypeScript files

jest + ts-jest + ttypescript

Steps

  1. Install the dependencies
npm install jest ts-jest typescript ttypescript jest-ts-auto-mock ts-auto-mock

you need to have ttypescript installed to patch and enable the TypeScript-runtime to apply the transformer.

  1. Add the transformer to your tsconfig.json
...
  "compilerOptions": {
    ...
    "plugins": [
      {
        "transform": "ts-auto-mock/transformer",
        "cacheBetweenTests": false
      }
    ]
    ...
  }
  ...

  • Remember to set cacheBetweenTests to false because Jest runs tests in parallel and ts-auto-mock doesn't yet support caching across parallel tests

  • You can find a JSON example here

  1. Add ts-jest to the transformation pattern in the Jest config

package.json / jest.config.js (without the jest scope)

...
  "jest": {
    "transform": {
      ".(ts|tsx)": "ts-jest"
    }
  }
...
  • You can find a JSON example here
  1. Add ttypescript to be used as ts-jest compiler

package.json / jest.config.js (without the jest scope)

...
  "jest": {
    "transform": {
        "^.+\\.tsx?$": [
          "ts-jest",
          {
            "compiler": "ttypescript"
          }
        ]
    }
  }
...
  • You can find a JSON example here
  1. Add jest-ts-auto-mock config file as your setup file

package.json / jest.config.js (without the jest scope)

...
  "jest": {
    "setupFiles": [
      "<rootDir>config.ts"
    ]
  }
...

config.ts

import 'jest-ts-auto-mock';

Example

  1. Create your first test
import { createMock } from 'ts-auto-mock';
interface Interface {
  a: string;
  b: number;
}
describe('reuse', () => {
  let mock: Interface;
  beforeEach(() => {
    mock = createMock<Interface>();
  });
  it('should work', () => {
    expect(mock.a).toBe('');
  });
});
  1. Run your test

package.json

...
  "scripts": {
    ...
    "test": "jest"
    ...
  }
...
npm run test

... and you are all done!

Config options

In the tsconfig.json you can add the config options next to the transformer name:

"plugins": [
  {
    "transform": "ts-auto-mock/transformer",
    "cacheBetweenTests": false,
    "features": ["random"]
  }
]

jest + ts-jest + ts-patch

Steps

  1. Install the dependencies
npm install jest ts-jest typescript ts-patch jest-ts-auto-mock ts-auto-mock

you need to have ts-patch installed to patch and enable the TypeScript-runtime to apply the transformer.

  1. Add the transformer to your tsconfig.json
...
  "compilerOptions": {
    ...
    "plugins": [
      {
        "transform": "ts-auto-mock/transformer",
        "cacheBetweenTests": false
      }
    ]
    ...
  }
  ...

  • Remember to set cacheBetweenTests to false because Jest runs tests in parallel and ts-auto-mock doesn't yet support caching across parallel tests

  • You can find a JSON example here

  1. Add ts-jest to the transformation pattern in the Jest config

package.json / jest.config.js (without the jest scope)

...
  "jest": {
    "transform": {
      ".(ts|tsx)": "ts-jest"
    }
  }
...
  • You can find a JSON example here
  1. Add ts-patch install to your prepare script in the package json

package.json

...
  "scripts": {
    ...,
    "prepare": "ts-patch install -s",
    ...
  }
...
  • You can find a JSON example here
  1. Add jest-ts-auto-mock config file as your setup file

package.json / jest.config.js (without the jest scope)

...
  "jest": {
    "setupFiles": [
      "<rootDir>config.ts"
    ]
  }
...

config.ts

import 'jest-ts-auto-mock';

Example

  1. Create your first test
import { createMock } from 'ts-auto-mock';
interface Interface {
  a: string;
  b: number;
}
describe('reuse', () => {
  let mock: Interface;
  beforeEach(() => {
    mock = createMock<Interface>();
  });
  it('should work', () => {
    expect(mock.a).toBe('');
  });
});
  1. Run your test

package.json

...
  "scripts": {
    ...
    "test": "jest"
    ...
  }
...
npm run test

... and you are all done!

Config options

In the tsconfig.json you can add the config options next to the transformer name:

"plugins": [
  {
    "transform": "ts-auto-mock/transformer",
    "cacheBetweenTests": false,
    "features": ["random"]
  }
]

Webpack

With Webpack, You can use any TypeScript-related loader that supports custom transformers, e.g. awesome-typescript-loader or ts-loader:

Steps

webpack.config.js

const tsAutoMockTransformer = require('ts-auto-mock/transformer').default;
module.exports = {
  // ...
  module: {
    rules: [
      {
        test: /\.ts$/,
        loader: 'ts-loader', // or 'awesome-typescript-loader'
        options: {
          getCustomTransformers: program => ({
              before: [
                  tsAutoMockTransformer(program)
              ]
          })
        }
      }
    ]
  }
};

Config options

In webpack.config.js you can pass a second parameter to the transformer:

before: [
  tsAutoMockTransformer(program, {
    features: ['random']
  })
]

ttypescript

See ttypescript's README for more information

Steps

tsconfig.json

{
  "compilerOptions": {
    //...,
    "plugins": [
      { "transform": "ts-auto-mock/transformer" }
    ]
  },
  //...
}

Config options

In the tsconfig.json you can add the config options next to the transformer name:

"plugins": [
  {
    "transform": "ts-auto-mock/transformer",
    "cacheBetweenTests": false,
    "features": ["random"]
  }
]

ts-patch

See ts-patch's README

Steps

Command to run to install it:

npm i ts-patch
ts-patch install

tsconfig.json

{
  "compilerOptions": {
    //...,
    "plugins": [
      { "transform": "ts-auto-mock/transformer" }
    ]
  },
  //...
}

Config options

In the tsconfig.json you can add the config options next to the transformer name:

"plugins": [
  {
    "transform": "ts-auto-mock/transformer",
    "cacheBetweenTests": false,
    "features": ["random"]
  }
]

ts-node + Mocha

Steps

tsnode.js

const tsAutoMockTransformer = require('ts-auto-mock/transformer').default;
require('ts-node').register({
  transformers: program => ({
    before: [
      tsAutoMockTransformer(program)
    ]
  })
});

Then inject the registration with the --require flag that Mocha passes on to Node.js:

mocha --require './tsnode.js' --watch-extensions ts,tsx "test/**/*.{ts,tsx}"

Config options

In tsnode.js you can pass a second parameter to the transformer:

before: [
  tsAutoMockTransformer(program, {
    features: ['random']
  })
]