Why assertions verify expected behavior in Cypress - The Real Reasons

The Big Idea

What if your tests could instantly tell you when something breaks, without you watching every step?

The Scenario

Imagine clicking through a website manually to check if every button works and every page looks right.

You have to remember what should happen and watch carefully for mistakes.

The Problem

Manually checking is slow and tiring.

You might miss errors because your eyes get tired or you forget what to look for.

It's hard to repeat the same checks exactly every time.

The Solution

Assertions automatically check if the website behaves as expected.

They tell you right away if something is wrong, so you don't have to guess.

This saves time and makes testing reliable and repeatable.

Before vs After

✗ Before

Visit page
Click button
Look if text changed
Remember if it was correct

✓ After

cy.visit('/page')
cy.get('button').click()
cy.contains('Expected Text').should('exist')

What It Enables

Assertions let you catch problems early and trust your tests to check the app for you automatically.

Real Life Example

When a new feature is added, assertions quickly confirm it works without breaking old features, saving hours of manual checking.

Key Takeaways

Manual checks are slow and error-prone.

Assertions automate verification of expected behavior.

This makes testing faster, reliable, and repeatable.

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