Testing scope functions and lambdas in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a scope function in Kotlin?

A scope function is a Kotlin function that executes a block of code within the context of an object, allowing you to access the object without repeating its name.

beginner

Name four common Kotlin scope functions.

The four common Kotlin scope functions are: let, run, with, and apply.

beginner

How does the 'let' scope function pass the object to the lambda?

'let' passes the object as a parameter named 'it' to the lambda, allowing you to use 'it' inside the block.

intermediate

What is the difference between 'apply' and 'run' in Kotlin scope functions?

'apply' returns the object itself and uses 'this' as the context inside the lambda, while 'run' returns the lambda result and also uses 'this' as the context.

intermediate

Why are lambdas useful in testing Kotlin scope functions?

Lambdas let you write concise blocks of code to test behavior inside scope functions, making it easy to check how the object is accessed and modified.

Which Kotlin scope function passes the object as 'it' to the lambda?

A run

B apply

C let

D with

'let' passes the object as 'it' to the lambda, while 'apply', 'run', and 'with' use 'this' as the context.

What does the 'apply' scope function return?

A The lambda result

B The original object

C A Boolean

D Null

'apply' returns the original object after executing the lambda block.

Which scope function is best when you want to configure an object and return it?

A apply

B let

C run

D also

'apply' is designed for configuring an object and returning it.

In Kotlin, what is a lambda?

A A block of code that can be passed around and executed

B A named function

C A variable type

D A class

A lambda is an anonymous block of code that can be passed as a parameter and executed.

Which scope function returns the result of the lambda instead of the object?

A with

B also

C apply

D run

'run' returns the result of the lambda, not the original object.

Explain how you would test a Kotlin scope function using a lambda.

Think about how the scope function passes the object and what you want to verify inside the lambda.

Describe the differences between 'let', 'apply', and 'run' in Kotlin scope functions.

Focus on how each function passes the object and what it returns.