assert.CallTracker - assert - Node

class assert.CallTracker

Usage in Deno

import assert from "node:assert";

Deprecated

This feature is deprecated and will be removed in a future version. Please consider using alternatives such as the mock helper function.

Methods



calls(exact?: number): () => void

The wrapper function is expected to be called exactly exact times. If the function has not been called exactly exact times when tracker.verify() is called, then tracker.verify() will throw an error.

import assert from 'node:assert';

// Creates call tracker.
const tracker = new assert.CallTracker();

function func() {}

// Returns a function that wraps func() that must be called exact times
// before tracker.verify().
const callsfunc = tracker.calls(func);



calls<Func extends (...args: any[]) => any>(fn?: Func,
exact?: number,
): Func



getCalls(fn: Function): CallTrackerCall[]

Example:

import assert from 'node:assert';

const tracker = new assert.CallTracker();

function func() {}
const callsfunc = tracker.calls(func);
callsfunc(1, 2, 3);

assert.deepStrictEqual(tracker.getCalls(callsfunc),
                       [{ thisArg: undefined, arguments: [1, 2, 3] }]);



report(): CallTrackerReportInformation[]

The arrays contains information about the expected and actual number of calls of the functions that have not been called the expected number of times.

import assert from 'node:assert';

// Creates call tracker.
const tracker = new assert.CallTracker();

function func() {}

// Returns a function that wraps func() that must be called exact times
// before tracker.verify().
const callsfunc = tracker.calls(func, 2);

// Returns an array containing information on callsfunc()
console.log(tracker.report());
// [
//  {
//    message: 'Expected the func function to be executed 2 time(s) but was
//    executed 0 time(s).',
//    actual: 0,
//    expected: 2,
//    operator: 'func',
//    stack: stack trace
//  }
// ]



reset(fn?: Function): void

Reset calls of the call tracker. If a tracked function is passed as an argument, the calls will be reset for it. If no arguments are passed, all tracked functions will be reset.

import assert from 'node:assert';

const tracker = new assert.CallTracker();

function func() {}
const callsfunc = tracker.calls(func);

callsfunc();
// Tracker was called once
assert.strictEqual(tracker.getCalls(callsfunc).length, 1);

tracker.reset(callsfunc);
assert.strictEqual(tracker.getCalls(callsfunc).length, 0);



verify(): void

Iterates through the list of functions passed to tracker.calls() and will throw an error for functions that have not been called the expected number of times.

import assert from 'node:assert';

// Creates call tracker.
const tracker = new assert.CallTracker();

function func() {}

// Returns a function that wraps func() that must be called exact times
// before tracker.verify().
const callsfunc = tracker.calls(func, 2);

callsfunc();

// Will throw an error since callsfunc() was only called once.
tracker.verify();