Minitest basics (assert style) in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Minitest assertion?

Consider the following Minitest code snippet. What will be the result when this test runs?

Ruby

require 'minitest/autorun'

class TestExample < Minitest::Test
  def test_sum
    sum = 2 + 3
    assert_equal(5, sum)
  end
end

A Test passes with no errors

B Test fails with an assertion error

C SyntaxError due to missing require

D RuntimeError due to undefined method

💡 Hint

Check what assert_equal expects and what sum is.

The assertion checks if sum equals 5. Since 2 + 3 is 5, the test passes without errors.

❓ Predict Output

intermediate

What error does this Minitest assertion raise?

What error will this test produce when run?

Ruby

require 'minitest/autorun'

class TestExample < Minitest::Test
  def test_truth
    assert(false, "This should fail")
  end
end

A NameError for undefined assert

B No error, test passes

C SyntaxError due to assert usage

D Minitest::Assertion with message 'This should fail'

💡 Hint

assert expects a true value to pass.

assert(false) fails and raises Minitest::Assertion with the given message.

🔧 Debug

advanced

Why does this Minitest assertion fail unexpectedly?

Examine the test below. Why does the assertion fail even though the values look equal?

Ruby

require 'minitest/autorun'

class TestExample < Minitest::Test
  def test_array_equality
    a = [1, 2, 3]
    b = [1, 2, 3.0]
    assert_equal(a, b)
  end
end

A Because 3 (integer) is not equal to 3.0 (float)

B Because arrays cannot be compared with assert_equal

C Because assert_equal requires strings, not arrays

D Because the test is missing a require statement

💡 Hint

Check the types of elements inside the arrays.

3 (Fixnum) and 3.0 (Float) are different types and not equal, so the assertion fails.

📝 Syntax

advanced

Which option causes a syntax error in this Minitest test?

Identify the option that will cause a syntax error when running this test code.

Ruby

require 'minitest/autorun'

class TestExample < Minitest::Test
  def test_truth
    assert true
  end
end

A

def test_truth
  assert true
end

B

def test_truth
  assert true

C

def test_truth
  assert(true)
end

D

dne
)eurt(tressa  
hturt_tset fed

💡 Hint

Check if all method definitions are properly closed.

Option B is missing the closing 'end' for the method, causing a syntax error.

🚀 Application

expert

How many assertions are run in this Minitest test method?

Given the following test method, how many assertions will Minitest count when this test runs?

Ruby

require 'minitest/autorun'

class TestExample < Minitest::Test
  def test_multiple_asserts
    assert_equal(4, 2 + 2)
    assert(3 > 1)
    assert_nil(nil)
  end
end

A 1

B 2

C 3

D 0

💡 Hint

Count each assert or assert_equal call as one assertion.

Each assert, assert_equal, and assert_nil counts as one assertion, so total is 3.