diff --git a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGenerator.kt b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGenerator.kt
index 8d6d9b74..78de75ba 100644
--- a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGenerator.kt
+++ b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGenerator.kt
@@ -13,7 +13,7 @@ class ProjectGraphGenerator(
     private val typeOfProjectRequested: TypeProjectRequested,
     private val classesPerModule: ClassesPerModule
 ) {
-    fun generate(): MutableList<ProjectGraph> {
+    fun generate(): List<ProjectGraph> {
         var generalCounter = 0
         var oldLayer = 0
         val nodes = mutableListOf<ProjectGraph>()
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGeneratorTest.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGeneratorTest.kt
index e13ccd4f..2b956375 100644
--- a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGeneratorTest.kt
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/ProjectGraphGeneratorTest.kt
@@ -2,6 +2,7 @@ package io.github.cdsap.projectgenerator
 
 import io.github.cdsap.projectgenerator.model.ClassesPerModule
 import io.github.cdsap.projectgenerator.model.ClassesPerModuleType
+import io.github.cdsap.projectgenerator.model.ProjectGraph
 import io.github.cdsap.projectgenerator.model.Shape
 import io.github.cdsap.projectgenerator.model.TypeProjectRequested
 import org.junit.jupiter.api.Assertions.*
@@ -11,6 +12,18 @@ import org.junit.jupiter.params.provider.EnumSource
 
 class ProjectGraphGeneratorTest {
 
+    @Test
+    fun `generated graph is consumed as a read-only result`() {
+        val nodes: List<ProjectGraph> = ProjectGraphGenerator(
+            numberOfLayers = 1,
+            distribution = listOf(1),
+            typeOfProjectRequested = TypeProjectRequested.JVM,
+            classesPerModule = ClassesPerModule(ClassesPerModuleType.FIXED, 10)
+        ).generate()
+
+        assertEquals(listOf("module_0_1", "module_1_2"), nodes.map { it.id })
+    }
+
     @ParameterizedTest
     @EnumSource(Shape::class)
     fun `generates every shape at the minimum module count`(shape: Shape) {