Sometimes, we want to unit test a Node.js module that requires other modules and how to mock the global require function.

In this article, we’ll look at how to unit test a Node.js module that requires other modules and how to mock the global require function.

How to unit test a Node.js module that requires other modules and how to mock the global require function?

To unit test a Node.js module that requires other modules and how to mock the global require function, we can use proxyquire.

To install it, we run

npm i proxyquire

Then we use it by writing

const proxyquire = require("proxyquire");
const assert = require("assert");
const pathStub = {};

//...

const foo = proxyquire("./foo", { path: pathStub });
assert.strictEqual(foo.bar("file.txt"), ".TXT");

to call proxyquire with the path to the module.

Then we call foo.bar from the foo module and check its returned value.

Conclusion

To unit test a Node.js module that requires other modules and how to mock the global require function, we can use proxyquire.