diff --git a/src/test/kotlin/com/vauthenticator/server/keys/adapter/java/KeyGeneratorMasterKeyRepositoryTest.kt b/src/test/kotlin/com/vauthenticator/server/keys/adapter/java/KeyGeneratorMasterKeyRepositoryTest.kt
index 55bd414f..3d999894 100644
--- a/src/test/kotlin/com/vauthenticator/server/keys/adapter/java/KeyGeneratorMasterKeyRepositoryTest.kt
+++ b/src/test/kotlin/com/vauthenticator/server/keys/adapter/java/KeyGeneratorMasterKeyRepositoryTest.kt
@@ -1,4 +1,31 @@
 package com.vauthenticator.server.keys.adapter.java
 
-//todo
-class KeyGeneratorMasterKeyRepositoryTest
\ No newline at end of file
+import com.vauthenticator.server.keys.domain.MasterKid
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertThrows
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+
+class KeyGeneratorMasterKeyRepositoryTest {
+
+    lateinit var uut: KeyGeneratorMasterKeyRepository
+
+    @BeforeEach
+    fun setUp() {
+        uut = KeyGeneratorMasterKeyRepository(KeyGeneratorMasterKeyStorage(mapOf("a_key" to "a_value")))
+    }
+
+
+    @Test
+    fun `when a key is retrieved`() {
+        val expected = "a_value"
+        val actual = uut.maskerKeyFor(MasterKid("a_key"))
+        assertEquals(expected, actual)
+    }
+
+
+    @Test
+    fun `when get a key from the storage fails`() {
+        assertThrows(NullPointerException::class.java) { uut.maskerKeyFor(MasterKid("a_key_2")) }
+    }
+}
\ No newline at end of file