Error Handling in Fakes

Fakes validate their usage and throw errors when used incorrectly. Understanding these errors helps you use fakes correctly.

Creating Fakes

Invalid Argument Type

When creating a fake with sinon.fake(f), if you provide an argument, it must be a function.

<<< ../../.vitepress/tests/docs/fakes/_index-3.test.js

Yield Methods

Missing Callback

Both fake.yields() and fake.yieldsAsync() expect the last argument to be a callback function. If you call the fake without a callback, it will throw an error.

For fake.yields():

<<< ../../.vitepress/tests/docs/fakes/api/yields.test.js

For fake.yieldsAsync():

<<< ../../.vitepress/tests/docs/fakes/api/yields-async.test.js

Best Practices

1. Always provide callbacks - When using fake.yields() or fake.yieldsAsync(), ensure the fake is called with a callback as the last argument
2. Type check arguments - Only pass functions to sinon.fake() when wrapping behavior
3. Use empty fakes - If you don't need specific behavior, call sinon.fake() without arguments to create an empty fake