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Frequently Asked Questions

The world instance isn’t available in my hooks or step definitions.

If you are referencing the world instance (which is bound to this) in a step definition or hook, then you cannot use ES6 arrow functions.

Cucumber uses apply internally to call your step definition and hook functions using the world object as this.

Using apply does not work with arrow functions, so if you need to reference the world, use a regular function.

Why do my definition patterns need to be globally unique instead of unique only within Given, When, Then?

To encourage a ubiquitous, non-ambiguous domain language. Using the same language to mean different things is basically the definition of ambiguous. If you have similar Given and Then patterns, try adding the word “should” to Then patterns.

Why am I seeing The "from" argument must be of type string. Received type undefined?

If when running cucumber-js you see an error with a stack trace like:

TypeError [ERR_INVALID_ARG_TYPE]: The "from" argument must be of type string. Received type undefined
    at validateString (internal/validators.js:125:11)
    at Object.relative (path.js:1162:5)
    ...

This usually an effect of one of:

  • Your project depends on cucumber-js, and also has a dependency (in node_modules) that depends on cucumber-js at a different version
  • You have a package that depends (even as a dev dependency) on cucumber-js linked (via npm link or yarn link)

These cases can cause two different instances of cucumber-js to be in play at runtime, which causes errors.

If removing the duplicate dependency is not possible, you can work around this by using import-cwd so your support code always requires cucumber-js from the current working directory (i.e. your host project):

const importCwd = require('import-cwd')
const { Given, When, Then } = importCwd('@cucumber/cucumber')