Kotlin test assertions - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of assertEquals(expected, actual) in Kotlin tests?

It checks if the actual value is equal to the expected value. If not, the test fails.

beginner

How does assertTrue(condition) work in Kotlin test assertions?

It verifies that the condition is true. If the condition is false, the test fails.

beginner

What does assertNotNull(value) check in Kotlin tests?

It checks that the value is not null. If it is null, the test fails.

intermediate

Explain the use of assertFailsWith<ExceptionType> { ... } in Kotlin tests.

It verifies that the code inside the block throws an exception of type ExceptionType. If no exception or a different type is thrown, the test fails.

intermediate

What is the difference between assertEquals and assertSame in Kotlin?

assertEquals checks if two objects are equal in value, while assertSame checks if they are the exact same object (reference equality).

Which assertion checks if a condition is true in Kotlin tests?

A assertTrue(condition)

B assertEquals(expected, actual)

C assertNotNull(value)

D assertFailsWith<Exception> { }

assertTrue(condition) verifies that the condition is true.

What happens if assertEquals(expected, actual) fails?

A The test fails and reports a mismatch

B The test passes silently

C The test throws a runtime exception unrelated to assertion

D Nothing happens

If the values are not equal, the test fails and reports the difference.

Which assertion would you use to check that a variable is not null?

A assertNull(value)

B assertTrue(value)

C assertNotNull(value)

D assertEquals(null, value)

assertNotNull(value) ensures the value is not null.

How do you test that a block of code throws a specific exception in Kotlin?

A assertEquals<Exception> { }

B assertFailsWith<Exception> { }

C assertTrue { }

D assertNotNull { }

assertFailsWith<Exception> { } checks for a specific exception.

What does assertSame(obj1, obj2) check?

A If obj1 and obj2 have the same value

B If obj2 is not null

C If obj1 is null

D If obj1 and obj2 are the same object in memory

assertSame checks if both references point to the exact same object.

Describe how you would use Kotlin test assertions to verify that a function returns the expected value and does not return null.

Think about checking value equality and null separately.

Explain how to test that a Kotlin function throws a specific exception when given invalid input.

Focus on the assertion that expects an exception.