Summary - Advanced testing
- Kotlin course
- Advanced
- Lesson 48/83
- 5 min
Combine runTest, Turbine and MockK to write a ViewModel test.
Summary - Advanced testing
In this group you saw the advanced testing tools: runTest for coroutines, Turbine for Flows, MockK for mocking, Testcontainers for real containers and kotest-property for property tests.
This lesson includes a small task that combines three of them: you will write a test that calls fetchUser inside runTest and prints the result. This pattern is the foundation of advanced Kotlin testing.
Practice Summary: write the fetchUser test
Define a suspend function fetchUser(id: Int): String that returns "Alex" when id is 1. In main open a runTest block; assign the result of fetchUser(1) to a variable, assert it with assertEquals("Alex", result) and print println(result).
Starter code
import kotlinx.coroutines.test.runTest
// suspend function: returns Alex for id=1
// open runTest block in main; assert and print fetchUser(1)Sample solution
import kotlinx.coroutines.test.runTest
import kotlin.test.assertEquals
suspend fun fetchUser(id: Int): String {
return "Alex"
}
fun main() = runTest {
val result = fetchUser(1)
assertEquals("Alex", result)
println(result)
}Expected output
Alex
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which builder is used to test a suspend function?
- Thread.sleep
- runBlocking
- runTest Correct answer
- Thread.start
Explanation: runTest opens a TestScope for suspend functions.
2 Complete the Turbine test block
scoreFlow().____ {
println(awaitItem())
awaitComplete()
}scoreFlow().test {
println(awaitItem())
awaitComplete()
}Explanation: scoreFlow().test opens a Turbine subscription.
3 Match the testing tools
| Term | Meaning |
|---|---|
runTest |
Coroutine test |
Turbine |
Flow test |
MockK |
Mocking |
kotest-property |
Property test |