#14 add save test

src/test/kotlin/guru/state/StateStorageTest.kt

@@ -2,6 +2,7 @@ package guru.state
 
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
+import java.io.File
 
 class StateStorageTest {
 
@@ -15,4 +16,16 @@ class StateStorageTest {
             .isNotNull()
             .isEmpty()
     }
+
+    @Test
+    fun `save empty state`() {
+        val storageName = "test"
+        val storage = StateStorage(storageName)
+
+        storage.save(emptyMap())
+
+        val state = File(storageName)
+        assertThat(state).exists()
+        state.delete()
+    }
 }