Model tests in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a basic model test class in Rails.

Ruby on Rails

class UserTest < ActiveSupport::[1]
end

Drag options to blanks, or click blank then click option'

ATestCase

BControllerTest

CIntegrationTest

DSystemTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using ControllerTest instead of TestCase

Using IntegrationTest for model tests

The base class for model tests in Rails is ActiveSupport::TestCase.

2fill in blank

medium

Complete the code to test that a User model is invalid without an email.

Ruby on Rails

test "should not save user without email" do
  user = User.new(email: nil)
  assert_not user.[1]?
end

Drag options to blanks, or click blank then click option'

Ainvalid

Bsave

Cpersisted

Dvalid

Attempts:

3 left

💡 Hint

Common Mistakes

Using save? which is not a method

Using invalid? which is not a method

The valid? method checks if the model passes validations.

3fill in blank

hard

Fix the error in the test to check uniqueness validation of username.

Ruby on Rails

test "username should be unique" do
  user1 = User.create(username: "testuser")
  user2 = User.new(username: "testuser")
  assert_not user2.[1]?
end

Drag options to blanks, or click blank then click option'

Avalid

Bsave

Ccreate

Dpersisted

Attempts:

3 left

💡 Hint

Common Mistakes

Using save? which is not a method

Using create which saves the record

To check if the new user is valid (fails uniqueness), use valid?.

4fill in blank

hard

Fill both blanks to test that a User model responds to name and email attributes.

Ruby on Rails

test "user responds to attributes" do
  user = User.new
  assert_respond_to user, :[1]
  assert_respond_to user, :[2]
end

Drag options to blanks, or click blank then click option'

Aname

Bemail

Cpassword

Dusername

Attempts:

3 left

💡 Hint

Common Mistakes

Using password or username instead of name or email

The test checks if the user object has name and email methods.

5fill in blank

hard

Fill all three blanks to test that a User model is invalid without name, email, and password.

Ruby on Rails

test "user is invalid without required fields" do
  user = User.new(name: nil, email: nil, password: nil)
  assert_not user.[1]?
  assert_includes user.errors[:[2]], "can't be blank"
  assert_includes user.errors[:[3]], "can't be blank"
end

Drag options to blanks, or click blank then click option'

Avalid

Bname

Cemail

Dpassword

Attempts:

3 left

💡 Hint

Common Mistakes

Using save? instead of valid?

Checking errors on wrong attributes

The test asserts the user is invalid and checks error messages for name and email fields.

Practice

1. What is the main purpose of model tests in a Rails application?

easy

A. To check data validations and model methods work correctly

B. To test the user interface layout

C. To verify database server performance

D. To check network connectivity

Solution

1. Step 1: Understand what model tests cover

   Model tests focus on the data layer, ensuring validations and methods behave as expected.

2. Step 2: Differentiate from other test types

   User interface and network tests are handled by other test types, not model tests.

3. Final Answer:

   To check data validations and model methods work correctly -> Option A

4. Quick Check:

   Model tests = data rules and logic [OK]

Hint: Model tests check data rules and methods only [OK]

Common Mistakes:

• Confusing model tests with UI tests
• Thinking model tests check server or network
• Assuming model tests check database performance

2. Which of the following is the correct syntax to test a presence validation on a Rails model attribute name using RSpec?

easy

A. expect(user).to validate_presence(:name)

B. expect(user).to be_validates_presence_of(:name)

C. expect(user).to have_presence_validation(:name)

D. expect(user).to validate_presence_of(:name)

Solution

1. Step 1: Recall RSpec validation matcher syntax

   The correct matcher is validate_presence_of(:attribute) used with expect(model).

2. Step 2: Check each option for exact syntax

   Only expect(user).to validate_presence_of(:name) matches the correct RSpec syntax for presence validation.

3. Final Answer:

   expect(user).to validate_presence_of(:name) -> Option D

4. Quick Check:

   RSpec presence validation = validate_presence_of [OK]

Hint: Use validate_presence_of matcher exactly in RSpec [OK]

Common Mistakes:

• Using incorrect matcher names
• Adding extra words like 'be_' or 'have_'
• Missing the '_of' suffix in matcher

3. Given this model test snippet:

RSpec.describe User, type: :model do
  it 'is invalid without email' do
    user = User.new(email: nil)
    expect(user).not_to be_valid
  end
end

What will this test check?

medium

A. That a User with an email is invalid

B. That the User model has a method called email

C. That a User without an email is invalid

D. That the User model saves successfully without email

Solution

1. Step 1: Analyze the test setup

   The test creates a User with email: nil, meaning no email is given.

2. Step 2: Understand the expectation

   The test expects user to NOT be valid, so it checks that missing email makes the user invalid.

3. Final Answer:

   That a User without an email is invalid -> Option C

4. Quick Check:

   Missing email -> invalid user [OK]

Hint: Check what attribute is nil and expected validity [OK]

Common Mistakes:

• Misreading the test as checking presence of method
• Thinking it tests saving instead of validation
• Confusing valid and invalid expectations

4. You wrote this model test:

it 'validates presence of title' do
  post = Post.new(title: '')
  expect(post).to be_valid
end

Why does this test fail?

medium

A. Because title is empty but test expects valid

B. Because Post.new requires a title argument

C. Because be_valid is not a valid matcher

D. Because the test is missing a database save

Solution

1. Step 1: Understand the test setup

   The test creates a Post with an empty string for title.

2. Step 2: Check the expectation vs validation

   If the model validates presence of title, empty string is invalid, but test expects valid, causing failure.

3. Final Answer:

   Because title is empty but test expects valid -> Option A

4. Quick Check:

   Empty title ≠ valid if presence validated [OK]

Hint: Empty string fails presence validation, expect invalid [OK]

Common Mistakes:

• Assuming empty string counts as present
• Thinking be_valid matcher is wrong
• Ignoring validation rules in test

5. You want to test a custom method full_name in your User model that combines first_name and last_name. Which is the best way to write this model test?

hard

A. Write a controller test that calls full_name

B. Create a User with first and last names, then expect user.full_name to equal their combination

C. Check that full_name is validated for presence

D. Test that full_name is a database column

Solution

1. Step 1: Identify what to test for a custom method

   Custom methods should be tested by calling them and checking their return values.

2. Step 2: Choose the test that verifies method output

   Creating a User with names and expecting full_name to return combined string is correct.

3. Final Answer:

   Create a User with first and last names, then expect user.full_name to equal their combination -> Option B

4. Quick Check:

   Test method output by calling it with sample data [OK]

Hint: Test method output by calling it on sample model instance [OK]

Common Mistakes:

• Testing method as if it were a database column
• Confusing validation tests with method tests
• Writing controller tests instead of model tests