avajs/ava · error · Error

not implemented

Error message

not implemented

What it means

Generic sentinel error thrown by the notImplemented placeholder in lib/assert.js. Certain Assertion API surface (methods stubbed out or not yet supported in this AVA version/environment) is wired to this stub, so calling them always throws instead of failing silently. The input at fault is the invocation of a stubbed assertion method.

Source

Thrown at lib/assert.js:34

		formatted: concordance.diffDescriptors(actualDescriptor, expectedDescriptor, options),
	};
}

function formatDescriptorWithLabel(label, descriptor) {
	return {
		label,
		formatted: concordance.formatDescriptor(descriptor, concordanceOptions),
	};
}

function formatWithLabel(label, value) {
	return formatDescriptorWithLabel(label, concordance.describe(value, concordanceOptions));
}

const noop = () => {};

const notImplemented = () => {
	throw new Error('not implemented');
};

export class AssertionError extends Error {
	constructor(message = '', {
		assertion,
		assertionStack = getAssertionStack(AssertionError),
		formattedDetails = [],
		improperUsage = null,
		cause,
	} = {}) {
		super(message, {cause});
		this.name = 'AssertionError';

		this.assertion = assertion;
		this.assertionStack = assertionStack;
		this.improperUsage = improperUsage;
		this.formattedDetails = formattedDetails;
	}

View on GitHub (pinned to bbfd946322)

Solutions

1. Identify which assertion method hit the stub and use a supported AVA assertion instead
2. Upgrade AVA — stubs typically mark features pending implementation in that version
3. Avoid shimming t.assert internals in test files

When it happens

Trigger: Thrown at lib/assert.js:34 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of avajs/ava@bbfd946322 (2026-09-02). Data as JSON: /api/errors/7dea4818daba6667. Report an issue: GitHub.