typescript

TypeScript example

This example shows how to use babel-plugin-mockable-imports in a project that uses TypeScript, together with Mocha for running tests.

Running the example

npm install
npm test

How it works

There are two steps to using TypeScript with this plugin:

1. Use Babel to transform code when running tests, instead of just the TypeScript compiler.
2. Use a helper to get access to the $imports object for a module being tested in order to mock dependencies. You can't import this directly from a module because the TypeScript compiler is unaware of its existence.

This is implemented as follows:

• The test/init.js file sets up processing of the TypeScript source files before the tests are run.

  It loads @babel/register and configures it to process TypeScript (.ts) files, applying the mockable-imports Babel plugin together with any other configured plugins.

• Babel configuration in .babelrc enables Babel to understand TypeScript source files using the @babel/preset-typescript preset

• A small helper module test/mock.ts provides a getImports helper to get access to the $imports object for a module in order to mock dependencies.

  Tests first import all of the exports of a module via import * as module from '<module>' and then initialize the $imports object using $imports = getImports(module).