Improves in-game command documentation

src/test/java/net/knarcraft/bookswithoutborders/encryption/MagicTest.java

@@ -0,0 +1,23 @@
+package net.knarcraft.bookswithoutborders.encryption;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+
+public class MagicTest {
+
+    @Test
+    public void magicEncryptionDecryptionTest() {
+        String plaintext = "Super secret text!";
+        Magic magic = new Magic();
+        String cipherText = magic.encryptText(plaintext);
+        assertNotNull(cipherText);
+        assertNotEquals(plaintext, cipherText);
+        String decrypted = magic.decryptText(cipherText);
+        assertNotNull(decrypted);
+        assertEquals(plaintext, decrypted);
+    }
+
+}