Assertions

Cypress bundles the popular Chai assertion library, as well as helpful extensions for Sinon and jQuery, bringing you dozens of powerful assertions for free.

Chai

https://github.com/chaijs/chai

BDD Assertions

These chainers are available for BDD assertions (expect/should). Aliases listed can be used interchangeably with their original chainer. You can see the entire list of available BDD Chai assertions here.

ChainerExample
notexpect(name).to.not.equal('Jane')
deepexpect(obj).to.deep.equal({ name: 'Jane' })
nestedexpect({a: {b: ['x', 'y']}}).to.have.nested.property('a.b[1]')
expect({a: {b: ['x', 'y']}}).to.nested.include({'a.b[1]': 'y'})
orderedexpect([1, 2]).to.have.ordered.members([1, 2]).but.not.have.ordered.members([2, 1])
anyexpect(arr).to.have.any.keys('age')
allexpect(arr).to.have.all.keys('name', 'age')
a(type)
Aliases: an
expect('test').to.be.a('string')
include(value)
Aliases: contain, includes, contains
expect([1,2,3]).to.include(2)
okexpect(undefined).to.not.be.ok
trueexpect(true).to.be.true
falseexpect(false).to.be.false
nullexpect(null).to.be.null
undefinedexpect(undefined).to.be.undefined
existexpect(myVar).to.exist
emptyexpect([]).to.be.empty
arguments
Aliases: Arguments
expect(arguments).to.be.arguments
equal(value)
Aliases: equals, eq
expect(42).to.equal(42)
deep.equal(value)expect({ name: 'Jane' }).to.deep.equal({ name: 'Jane' })
eql(value)
Aliases: eqls
expect({ name: 'Jane' }).to.eql({ name: 'Jane' })
greaterThan(value)
Aliases: gt, above
expect(10).to.be.greaterThan(5)
least(value)
Aliases: gte
expect(10).to.be.at.least(10)
lessThan(value)
Aliases: lt, below
expect(5).to.be.lessThan(10)
most(value)
Aliases: lte
expect('test').to.have.length.of.at.most(4)
within(start, finish)expect(7).to.be.within(5,10)
instanceOf(constructor)
Aliases: instanceof
expect([1, 2, 3]).to.be.instanceOf(Array)
property(name, [value])expect(obj).to.have.property('name')
deep.property(name, [value])expect(deepObj).to.have.deep.property('tests[1]', 'e2e')
ownProperty(name)
Aliases: haveOwnProperty, own.property
expect('test').to.have.ownProperty('length')
ownPropertyDescriptor(name)
Aliases: haveOwnPropertyDescriptor
expect({a: 1}).to.have.ownPropertyDescriptor('a')
lengthOf(value)expect('test').to.have.lengthOf(3)
match(RegExp)
Aliases: matches
expect('testing').to.match(/^test/)
string(string)expect('testing').to.have.string('test')
keys(key1, [key2], [...])
Aliases: key
expect({ pass: 1, fail: 2 }).to.have.keys('pass', 'fail')
throw(constructor)
Aliases: throws, Throw
expect(fn).to.throw(Error)
respondTo(method)
Aliases: respondsTo
expect(obj).to.respondTo('getName')
itselfexpect(Foo).itself.to.respondTo('bar')
satisfy(method)
Aliases: satisfies
expect(1).to.satisfy((num) => { return num > 0 })
closeTo(expected, delta)
Aliases: approximately
expect(1.5).to.be.closeTo(1, 0.5)
members(set)expect([1, 2, 3]).to.include.members([3, 2])
oneOf(values)expect(2).to.be.oneOf([1,2,3])
change(function)
Aliases: changes
expect(fn).to.change(obj, 'val')
increase(function)
Aliases: increases
expect(fn).to.increase(obj, 'val')
decrease(function)
Aliases: decreases
expect(fn).to.decrease(obj, 'val')

These getters are also available for BDD assertions. They don't actually do anything, but they enable you to write clear, english sentences.

Chainable getters
to, be, been, is, that, which, and, has, have, with, at, of, same

TDD Assertions

These assertions are available for TDD assertions (assert). You can see the entire list of available Chai assertions here.

AssertionExample
.isOk(object, [message])assert.isOk('everything', 'everything is ok')
.isNotOk(object, [message])assert.isNotOk(false, 'this will pass')
.equal(actual, expected, [message])assert.equal(3, 3, 'vals equal')
.notEqual(actual, expected, [message])assert.notEqual(3, 4, 'vals not equal')
.strictEqual(actual, expected, [message])assert.strictEqual(true, true, 'bools strict eq')
.notStrictEqual(actual, expected, [message])assert.notStrictEqual(5, '5', 'not strict eq')
.deepEqual(actual, expected, [message])assert.deepEqual({ id: '1' }, { id: '1' })
.notDeepEqual(actual, expected, [message])assert.notDeepEqual({ id: '1' }, { id: '2' })
.isAbove(valueToCheck, valueToBeAbove, [message])assert.isAbove(6, 1, '6 greater than 1')
.isAtLeast(valueToCheck, valueToBeAtLeast, [message])assert.isAtLeast(5, 2, '5 gt or eq to 2')
.isBelow(valueToCheck, valueToBeBelow, [message])assert.isBelow(3, 6, '3 strict lt 6')
.isAtMost(valueToCheck, valueToBeAtMost, [message])assert.isAtMost(4, 4, '4 lt or eq to 4')
.isTrue(value, [message])assert.isTrue(true, 'this val is true')
.isNotTrue(value, [message])assert.isNotTrue('tests are no fun', 'val not true')
.isFalse(value, [message])assert.isFalse(false, 'val is false')
.isNotFalse(value, [message])assert.isNotFalse('tests are fun', 'val not false')
.isNull(value, [message])assert.isNull(err, 'there was no error')
.isNotNull(value, [message])assert.isNotNull('hello', 'is not null')
.isNaN(value, [message])assert.isNaN(NaN, 'NaN is NaN')
.isNotNaN(value, [message])assert.isNotNaN(5, '5 is not NaN')
.exists(value, [message])assert.exists(5, '5 is not null or undefined')
.notExists(value, [message])assert.notExists(null, 'val is null or undefined')
.isUndefined(value, [message])assert.isUndefined(undefined, 'val is undefined')
.isDefined(value, [message])assert.isDefined('hello', 'val has been defined')
.isFunction(value, [message])assert.isFunction(x => x * x, 'val is func')
.isNotFunction(value, [message])assert.isNotFunction(5, 'val not funct')
.isObject(value, [message])assert.isObject({num: 5}, 'val is object')
.isNotObject(value, [message])assert.isNotObject(3, 'val not object')
.isArray(value, [message])assert.isArray(['unit', 'e2e'], 'val is array')
.isNotArray(value, [message])assert.isNotArray('e2e', 'val not array')
.isString(value, [message])assert.isString('e2e', 'val is string')
.isNotString(value, [message])assert.isNotString(2, 'val not string')
.isNumber(value, [message])assert.isNumber(2, 'val is number')
.isNotNumber(value, [message])assert.isNotNumber('e2e', 'val not number')
.isFinite(value, [message])assert.isFinite('e2e', 'val is finite')
.isBoolean(value, [message])assert.isBoolean(true, 'val is bool')
.isNotBoolean(value, [message])assert.isNotBoolean('true', 'val not bool')
.typeOf(value, name, [message])assert.typeOf('e2e', 'string', 'val is string')
.notTypeOf(value, name, [message])assert.notTypeOf('e2e', 'number', 'val not number')

Chai-jQuery

https://github.com/chaijs/chai-jquery

These chainers are available when asserting about a DOM object.

You will commonly use these chainers after using DOM commands like: cy.get(), cy.contains(), etc.

ChainersAssertion
attr(name, [value])expect($el).to.have.attr('foo', 'bar')
prop(name, [value])expect($el).to.have.prop('disabled', false)
css(name, [value])expect($el).to.have.css('background-color', 'rgb(0, 0, 0)')
data(name, [value])expect($el).to.have.data('foo', 'bar')
class(className)expect($el).to.have.class('foo')
id(id)expect($el).to.have.id('foo')
html(html)expect($el).to.have.html('I love testing')
text(text)expect($el).to.have.text('I love testing')
value(value)expect($el).to.have.value('[email protected]')
visibleexpect($el).to.be.visible
hiddenexpect($el).to.be.hidden
selectedexpect($option).not.to.be.selected
checkedexpect($input).not.to.be.checked
focus[ed]expect($input).not.to.be.focused
expect($input).to.have.focus
enabledexpect($input).to.be.enabled
disabledexpect($input).to.be.disabled
emptyexpect($el).not.to.be.empty
existexpect($nonexistent).not.to.exist
match(selector)expect($emptyEl).to.match(':empty')
contain(text)expect($el).to.contain('text')
descendants(selector)expect($el).to.have.descendants('div')

Sinon-Chai

https://github.com/domenic/sinon-chai

These chainers are used on assertions with cy.stub() and cy.spy().

Sinon.JS property/methodAssertion
calledexpect(spy).to.be.called
callCountexpect(spy).to.have.callCount(n)
calledOnceexpect(spy).to.be.calledOnce
calledTwiceexpect(spy).to.be.calledTwice
calledThriceexpect(spy).to.be.calledThrice
calledBeforeexpect(spy1).to.be.calledBefore(spy2)
calledAfterexpect(spy1).to.be.calledAfter(spy2)
calledWithNewexpect(spy).to.be.calledWithNew
alwaysCalledWithNewexpect(spy).to.always.be.calledWithNew
calledOnexpect(spy).to.be.calledOn(context)
alwaysCalledOnexpect(spy).to.always.be.calledOn(context)
calledWithexpect(spy).to.be.calledWith(...args)
alwaysCalledWithexpect(spy).to.always.be.calledWith(...args)
calledWithExactlyexpect(spy).to.be.calledWithExactly(...args)
alwaysCalledWithExactlyexpect(spy).to.always.be.calledWithExactly(...args)
calledWithMatchexpect(spy).to.be.calledWithMatch(...args)
alwaysCalledWithMatchexpect(spy).to.always.be.calledWithMatch(...args)
returnedexpect(spy).to.have.returned(returnVal)
alwaysReturnedexpect(spy).to.have.always.returned(returnVal)
threwexpect(spy).to.have.thrown(errorObjOrErrorTypeStringOrNothing)
alwaysThrewexpect(spy).to.have.always.thrown(errorObjOrErrorTypeStringOrNothing)

Adding New Assertions

Because we are using chai, that means you can extend it however you'd like. Cypress will "just work" with new assertions added to chai. You can:

  • Write your own chai assertions as documented here.
  • npm install any existing chai library and import into your test file or support file.

Common Assertions

Here is a list of common element assertions. Notice how we use these assertions (listed above) with .should(). You may also want to read about how Cypress retries assertions.

Length

// retry until we find 3 matching <li.selected>
cy.get('li.selected').should('have.length', 3)

Class

// retry until this input does not have class disabled
cy.get('form').find('input').should('not.have.class', 'disabled')

Value

// retry until this textarea has the correct value
cy.get('textarea').should('have.value', 'foo bar baz')

Text Content

// assert the element's text content is exactly the given text
cy.get('#user-name').should('have.text', 'Joe Smith')
// assert the element's text includes the given substring
cy.get('#address').should('include.text', 'Atlanta')
// retry until this span does not contain 'click me'
cy.get('a').parent('span.help').should('not.contain', 'click me')
// the element's text should start with "Hello"
cy.get('#greeting')
  .invoke('text')
  .should('match', /^Hello/)
// tip: use cy.contains to find element with its text
// matching the given regular expression
cy.contains('#a-greeting', /^Hello/)

Tip: read about assertions against a text with non-breaking space entities in How do I get an element's text contents?

Visibility

// retry until the button with id "form-submit" is visible
cy.get('button#form-submit').should('be.visible')
// retry until the list item with
// text "write tests" is visible
cy.contains('.todo li', 'write tests').should('be.visible')

Note: if there are multiple elements, the assertions be.visible and not.be.visible act differently:

// retry until SOME elements are visible
cy.get('li').should('be.visible')
// retry until EVERY element is invisible
cy.get('li.hidden').should('not.be.visible')

Watch the short video "Multiple elements and should('be.visible') assertion" that shows how to correctly check the visibility of elements.

Existence

// retry until loading spinner no longer exists
cy.get('#loading').should('not.exist')

State

// retry until our radio is checked
cy.get(':radio').should('be.checked')

CSS

// retry until .completed has matching css
cy.get('.completed').should('have.css', 'text-decoration', 'line-through')
// retry while .accordion css has the "display: none" property
cy.get('#accordion').should('not.have.css', 'display', 'none')

Disabled property

<input type="text" id="example-input" disabled />
cy.get('#example-input')
  .should('be.disabled')
  // let's enable this element from the test
  .invoke('prop', 'disabled', false)

cy.get('#example-input')
  // we can use "enabled" assertion
  .should('be.enabled')
  // or negate the "disabled" assertion
  .and('not.be.disabled')

Negative assertions

There are positive and negative assertions. Examples of positive assertions are:

cy.get('.todo-item').should('have.length', 2).and('have.class', 'completed')

The negative assertions have the "not" chainer prefixed to the assertion. Examples of negative assertions are:

cy.contains('first todo').should('not.have.class', 'completed')
cy.get('#loading').should('not.be.visible')

⚠️ False passing tests

Negative assertions may pass for reasons you weren't expecting. Let's say we want to test that a Todo list app adds a new Todo item after typing the Todo and pressing enter.

Positive assertions

When adding an element to the list and using a positive assertion, the test asserts a specific number of Todo items in our application.

The test below may still falsely pass if the application behaves unexpectedly, like adding a blank Todo, instead of adding the new Todo with the text "Write tests".

cy.get('li.todo').should('have.length', 2)
cy.get('input#new-todo').type('Write tests{enter}')

// using a positive assertion to check the exact number of items
cy.get('li.todo').should('have.length', 3)

Negative assertions

But when using a negative assertion in the test below, the test can falsely pass when the application behaves in multiple unexpected ways:

  • The app deletes the entire list of Todo items instead of inserting the 3rd Todo
  • The app deletes a Todo instead of adding a new Todo
  • The app adds a blank Todo
  • An infinite variety of possible application mistakes
cy.get('li.todo').should('have.length', 2)
cy.get('input#new-todo').type('Write tests{enter}')

// using negative assertion to check it's not a number of items
cy.get('li.todo').should('not.have.length', 2)

Recommendation

We recommend using negative assertions to verify that a specific condition is no longer present after the application performs an action. For example, when a previously completed item is unchecked, we might verify that a CSS class is removed.

// at first the item is marked completed
cy.contains('li.todo', 'Write tests')
  .should('have.class', 'completed')
  .find('.toggle')
  .click()

// the CSS class has been removed
cy.contains('li.todo', 'Write tests').should('not.have.class', 'completed')

For more examples, please read the blog post Be Careful With Negative Assertions.

Should callback

If built-in assertions are not enough, you can write your own assertion function and pass it as a callback to the .should() command. Cypress will automatically retry the callback function until it passes or the command times out. See the .should() documentation.

<div class="main-abc123 heading-xyz987">Introduction</div>
cy.get('div').should(($div) => {
  expect($div).to.have.length(1)

  const className = $div[0].className

  // className will be a string like "main-abc123 heading-xyz987"
  expect(className).to.match(/heading-/)
})

Multiple assertions

You can attach multiple assertions to the same command.

<a class="assertions-link active" href="https://on.cypress.io" target="_blank"
  >Cypress Docs</a
>
cy.get('.assertions-link')
  .should('have.class', 'active')
  .and('have.attr', 'href')
  .and('include', 'cypress.io')

Note that all chained assertions will use the same reference to the original subject. For example, if you wanted to test a loading element that first appears and then disappears, the following WILL NOT WORK because the same element cannot be visible and invisible at the same time:

// ⛔️ DOES NOT WORK
cy.get('#loading').should('be.visible').and('not.be.visible')

Instead you should split the assertions and re-query the element:

// ✅ THE CORRECT WAY
cy.get('#loading').should('be.visible')
cy.get('#loading').should('not.be.visible')

See also