Why assertions verify expected behavior in Cypress

Introduction

Assertions check if the app works as we expect. They help catch mistakes early by comparing actual results to what should happen.

When you want to confirm a button is visible before clicking it.

When you need to check if a form shows an error message after wrong input.

When verifying that a page loads the correct title.

When ensuring a list contains the expected number of items.

When confirming a user is redirected to the right page after login.

Syntax

Cypress

cy.get('selector').should('assertion', expectedValue)

cy.get('selector') finds the element on the page.

.should() is where you check the expected behavior.

Examples

Check if the button is visible on the page.

Cypress

cy.get('button').should('be.visible')

Verify the input field contains the text 'hello'.

Cypress

cy.get('input').should('have.value', 'hello')

Assert that the current URL includes '/dashboard'.

Cypress

cy.url().should('include', '/dashboard')

Sample Program

This test opens the login page, enters wrong password, clicks submit, and checks if the error message appears with correct text.

Cypress

describe('Login Page Test', () => {
  it('shows error on wrong password', () => {
    cy.visit('https://example.com/login')
    cy.get('input[name="username"]').type('user1')
    cy.get('input[name="password"]').type('wrongpass')
    cy.get('button[type="submit"]').click()
    cy.get('.error-message').should('be.visible')
    cy.get('.error-message').should('contain.text', 'Invalid password')
  })
})

Important Notes

Assertions stop the test if they fail, so you know exactly where the problem is.

Use clear and simple assertions to make tests easy to understand.

Summary

Assertions confirm the app behaves as expected.

They help find bugs early by checking real results against expected ones.

In Cypress, use .should() with selectors to write assertions.

Practice

1. Why do we use assertions in Cypress tests?

easy

A. To change the app's data

B. To slow down the test execution

C. To skip parts of the test

D. To check if the app behaves as expected

Solution

1. Step 1: Understand the purpose of assertions

   Assertions are used to verify that the application behaves as expected during tests.

2. Step 2: Identify the correct purpose in options

   Only To check if the app behaves as expected states that assertions check expected behavior, which is correct.

3. Final Answer:

   To check if the app behaves as expected -> Option D

4. Quick Check:

   Assertions verify expected behavior = C [OK]

Hint: Assertions confirm expected results, not change behavior [OK]

Common Mistakes:

• Thinking assertions change app data
• Believing assertions slow tests down
• Confusing assertions with test flow control

2. Which of the following is the correct syntax to assert that a button with id submit is visible in Cypress?

easy

A. cy.get('submit').should('visible')

B. cy.find('#submit').assert('visible')

C. cy.get('#submit').should('be.visible')

D. cy.get('#submit').check('visible')

Solution

1. Step 1: Recall correct Cypress assertion syntax

   In Cypress, cy.get(selector).should('be.visible') checks visibility.

2. Step 2: Compare options with correct syntax

   cy.get('#submit').should('be.visible') matches the correct syntax exactly; others have wrong methods or missing quotes.

3. Final Answer:

   cy.get('#submit').should('be.visible') -> Option C

4. Quick Check:

   Correct assertion syntax = B [OK]

Hint: Use cy.get() with .should('be.visible') for visibility checks [OK]

Common Mistakes:

• Missing '#' for id selector
• Using wrong assertion method like check or assert
• Omitting quotes around assertion string

3. What will happen when this Cypress code runs?

cy.get('.message').should('contain.text', 'Success')

medium

A. Test passes if element with class 'message' contains text 'Success'

B. Test fails if element with class 'message' contains text 'Success'

C. Test passes regardless of element text

D. Test throws a syntax error

Solution

1. Step 1: Analyze the assertion syntax

   The code uses .should('contain.text', 'Success'), which is a valid Cypress assertion chainer.

2. Step 2: Determine test outcome

   The test passes if the element with class 'message' contains the text 'Success'; otherwise, it fails.

3. Final Answer:

   Test passes if element with class 'message' contains text 'Success' -> Option A

4. Quick Check:

   Valid 'contain.text' assertion = A [OK]

Hint: 'contain.text' is valid in Cypress for text content check [OK]

Common Mistakes:

• Thinking 'contain.text' is invalid
• Predicting pass/fail based on text presence
• Confusing with other assertion methods

4. Identify the error in this Cypress assertion:

cy.get('.title').should('have.text', Success)

medium

A. Missing quotes around 'Success' string

B. Wrong selector syntax

C. Incorrect assertion method 'have.text'

D. No error, code is correct

Solution

1. Step 1: Check the assertion syntax

   The text 'Success' must be a string, so it needs quotes around it.

2. Step 2: Identify the error in the code

   The code misses quotes around Success, causing a syntax error or undefined variable.

3. Final Answer:

   Missing quotes around 'Success' string -> Option A

4. Quick Check:

   String literals need quotes = A [OK]

Hint: Always put quotes around text in assertions [OK]

Common Mistakes:

• Forgetting quotes around string values
• Thinking selector syntax is wrong
• Misunderstanding assertion method names

5. You want to verify a checkbox with id agree is checked after clicking it. Which assertion correctly verifies this expected behavior?

hard

A. cy.get('#agree').click().should('have.value', 'checked')

B. cy.get('#agree').click().should('be.checked')

C. cy.get('#agree').click().should('contain.text', 'checked')

D. cy.get('#agree').click().should('be.visible')

Solution

1. Step 1: Understand the goal of the assertion

   We want to confirm the checkbox is checked after clicking it.

2. Step 2: Identify the correct assertion method

   The correct assertion is should('be.checked') which verifies checkbox state.

3. Step 3: Evaluate options

   cy.get('#agree').click().should('be.checked') uses be.checked, which is correct. The other options incorrectly check value, visibility, or text content.

4. Final Answer:

   cy.get('#agree').click().should('be.checked') -> Option B

5. Quick Check:

   should('be.checked') = D [OK]

Hint: Use .should('be.checked') to confirm checkbox is selected [OK]

Common Mistakes:

• Checking visibility instead of checked state
• Looking for text 'checked' inside checkbox
• Using value instead of checked property