Test Resources

Access test resources easily in Kotlin Multiplatform

Accessing test resources in Kotlin Multiplatform can be tricky. FileKit provides a simple solution with FileKit.projectDir.

The Problem

In KMP, there’s no built-in way to access files in your test resources folder across all platforms. Traditional approaches like ClassLoader.getResource() don’t work consistently.

The Solution

FileKit provides FileKit.projectDir which returns the root directory of your project. From there, you can easily navigate to your test resources:

val resourceDirectory = FileKit.projectDir / "src/commonTest/resources"
val testFile = resourceDirectory / "test-data.txt"

Example

Here’s a complete example of a multiplatform test that reads a file from test resources:

import io.github.vinceglb.filekit.FileKit
import io.github.vinceglb.filekit.div
import io.github.vinceglb.filekit.readString
import kotlinx.coroutines.test.runTest
import kotlin.test.Test
import kotlin.test.assertEquals

class MyTest {
    private val resourceDirectory = FileKit.projectDir / "src/commonTest/resources"
    private val textFile = resourceDirectory / "hello.txt"
    private val imageFile = resourceDirectory / "image.png"

    @Test
    fun readTestFile() = runTest {
        val content = textFile.readString()
        assertEquals(expected = "Hello, World!", actual = content)
    }

    @Test
    fun checkFileExists() {
        assertTrue { textFile.exists() }
        assertTrue { imageFile.exists() }
    }
}

Project Structure

Your test resources should be placed in the appropriate source set:

my-project/
├── src/
│   ├── commonMain/
│   ├── commonTest/
│   │   ├── kotlin/
│   │   │   └── MyTest.kt
│   │   └── resources/
│   │       ├── hello.txt
│   │       └── image.png
│   └── ...

Use the / operator (via div) to build paths in a readable way:

val file = FileKit.projectDir / "src" / "commonTest" / "resources" / "data.json"

Supported Platforms

FileKit.projectDir is available on all non-web platforms:

Platform	Supported
Android	✅
iOS	✅
macOS	✅
JVM	✅
JS	❌
WASM	❌