unittest: Added unit test for the quit/exit command

src/test/java/org/bitbiome/commands/QuitCommandTest.java

@@ -0,0 +1,15 @@
+package org.bitbiome.commands;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class QuitCommandTest {
+
+
+    @Test
+    public void testQuitCommand() {
+        assertEquals("You quitted!", QuitCommand.getQuitMessage());
+    }
+
+}