jasmine-tests

jasmine-tests

Overview

Per jasmine.github.io/pages/getting_started.html:

Jasmine (~2010) is the original BDD-style JS test framework. Most of Jest's API descends from Jasmine - describe, it, beforeEach, expect(...).toBe(...), spies - were all Jasmine patterns first.

Modern usage:

• Legacy AngularJS apps standardized on Jasmine + Karma.
• Migration cases from Jasmine to Jest (mostly mechanical).
• Minimal-deps projects that want no external matcher libraries.

For new browser-side projects, prefer vitest-tests or jest-tests. This skill covers the maintenance use case + the migration path.

When to use

• Existing Karma + Jasmine setup the team isn't ready to migrate.
• Legacy AngularJS (1.x) project (Karma + Jasmine is the official Angular CLI default until very recent versions).
• Minimal-dependency requirement (no separate Chai / Sinon).

Step 1 - Install

npm install --save-dev jasmine
npx jasmine init

init creates spec/support/jasmine.json:

{
  "spec_dir": "spec",
  "spec_files": [
    "**/*[sS]pec.js"
  ],
  "helpers": [
    "helpers/**/*.js"
  ],
  "stopSpecOnExpectationFailure": false,
  "random": true
}

Step 2 - First test

// spec/sumSpec.js
const { sum } = require('../src/sum');

describe('sum', () => {
  it('adds 1 + 2 to equal 3', () => {
    expect(sum(1, 2)).toBe(3);
  });
});

Wire package.json:

{
  "scripts": {
    "test": "jasmine"
  }
}

Step 3 - Built-in matchers

Per jasmine.github.io/api/edge/matchers.html:

Matcher	Use
toBe(expected)	Strict equality (===)
toEqual(expected)	Deep equality
toBeTruthy() / toBeFalsy()	Boolean coercion
toBeGreaterThan(n) / toBeLessThan(n)	Numeric comparison
toBeCloseTo(n, precision)	Float comparison
toContain(substring)	String / array containment
toMatch(regex)	Regex match
toThrow() / toThrowError(...)	Sync throw
toBeInstanceOf(Class)	Type check
toBeDefined() / toBeUndefined() / toBeNull()	Existence

No need for Chai's expect(x).to.equal(y) style - Jasmine's matchers are first-class.

Step 4 - Spies (built-in mocking)

describe('user service', () => {
  it('calls api on save', () => {
    spyOn(api, 'post').and.returnValue(Promise.resolve({ id: 1 }));
    userService.save(user);
    expect(api.post).toHaveBeenCalledWith('/users', user);
  });

  it('standalone spy', () => {
    const spy = jasmine.createSpy('callback');
    eventEmitter.on('save', spy);
    eventEmitter.emit('save');
    expect(spy).toHaveBeenCalled();
  });
});

Spy methods:

Method	Effect
spyOn(obj, 'method')	Replace method with spy; returns undefined by default
.and.returnValue(value)	Configure return
.and.callFake(fn)	Custom implementation
.and.callThrough()	Spy + delegate to real impl
jasmine.createSpy(name)	Standalone spy
jasmine.createSpyObj(name, ['m1', 'm2'])	Object with multiple spies

Step 5 - Async patterns

// async/await (Jasmine 3.x+)
it('async test', async () => {
  const result = await fetchData();
  expect(result).toBe('expected');
});

// Promise return (Jasmine 2.x+)
it('promise test', () => {
  return fetchData().then(result => {
    expect(result).toBe('expected');
  });
});

// Done callback (legacy)
it('callback test', (done) => {
  fetchData((err, result) => {
    expect(result).toBe('expected');
    done();
  });
});

Step 6 - Hooks

describe('User service', () => {
  beforeAll(() => { /* once before all */ });
  afterAll(() => { /* once after all */ });
  beforeEach(() => { /* before each spec */ });
  afterEach(() => { /* after each spec */ });
});

Same pattern as Jest / Vitest.

Step 7 - Karma integration (browser tests)

For browser-environment tests (legacy Angular CLI default):

npm install --save-dev karma karma-jasmine karma-chrome-launcher

karma.conf.js:

module.exports = function(config) {
  config.set({
    frameworks: ['jasmine'],
    files: ['src/**/*.spec.js'],
    browsers: ['ChromeHeadless'],
    singleRun: true,
    reporters: ['progress', 'junit'],
  });
};

npx karma start

Important migration note: Karma is in maintenance-only mode as of 2023; AngularJS reached end-of-life Jan 2022; new Angular projects use Jest or Vitest. Karma + Jasmine setups are explicitly legacy.

Step 8 - Migration to Jest path

Jest's API is mostly compatible with Jasmine - typical migration steps:

1. Replace spyOn().and.returnValue() with jest.spyOn().mockReturnValue()
2. Replace jasmine.createSpy() with jest.fn()
3. Replace jasmine.createSpyObj() with manual jest.fn() per method
4. Replace expect().toBeNan() with expect(Number.isNaN()).toBe(true) (matcher renamed)
5. Add jest.config.js with appropriate testMatch
6. Drop Karma if used (Jest handles its own jsdom env)

For automated migration: jest-codemods package handles ~80% of the syntax transformations.

Step 9 - CI integration

- run: npm ci
- run: npx jasmine --config=spec/support/jasmine.json --reporter=jasmine-spec-reporter
# Or with JUnit XML for CI dashboards:
- run: npx jasmine --reporter=jasmine-junit-xml-reporter

Anti-patterns

Anti-pattern	Why it fails	Fix
Start new project with Jasmine + Karma in 2026	Legacy stack; Karma in maintenance	Use Vitest / Jest for new (Step 7)
spyOn without .and configurator	Spy returns undefined; tests pass-by-accident	Always configure (Step 4)
Use fdescribe / fit (focus) accidentally	Suite runs only focused specs	Lint rule equivalent of mocha/no-exclusive-tests
Mix Jasmine assertions with Chai	Two assertion APIs in one suite; reader confusion	Pick one (Step 3 - Jasmine's are sufficient)
Skip migration codemods when moving to Jest	Manual rewrites slow + error-prone	jest-codemods (Step 8)

Limitations

• Karma maintenance-only; for browser-environment tests, prefer Vitest browser-mode.
• Snapshot testing not built-in (use jasmine-snapshot or migrate to Jest).
• ESM support workable but rough; new Jasmine versions improving.
• Mock-server / fetch-mock ecosystems weaker than Jest's; more manual setup.

References

• jas-start - getting started
• jasmine.github.io/api/edge - API reference
• jasmine.github.io/api/edge/matchers.html - matcher list
• karma-runner.github.io - Karma (legacy)
• github.com/skovhus/jest-codemods - Jasmine→Jest migration codemods
• jest-tests, vitest-tests, mocha-tests, ava-tests - sister tools
• test-code-conventions - cross-plugin: test code hygiene