Fixed most reported issues by SonarCloud.

bytecode/src/main/java/com/iluwatar/bytecode/App.java

@@ -58,12 +58,14 @@ public class App {
     var vm = new VirtualMachine();
     vm.getWizards()[0] = wizard;
 
-    interpretInstruction("LITERAL 0", vm);
-    interpretInstruction("LITERAL 0", vm);
+    String literal = "LITERAL 0";
+
+    interpretInstruction(literal, vm);
+    interpretInstruction(literal, vm);
     interpretInstruction("GET_HEALTH", vm);
-    interpretInstruction("LITERAL 0", vm);
+    interpretInstruction(literal, vm);
     interpretInstruction("GET_AGILITY", vm);
-    interpretInstruction("LITERAL 0", vm);
+    interpretInstruction(literal, vm);
     interpretInstruction("GET_WISDOM ", vm);
     interpretInstruction("ADD", vm);
     interpretInstruction("LITERAL 2", vm);

bytecode/src/test/java/com/iluwatar/bytecode/AppTest.java

@@ -25,13 +25,22 @@ package com.iluwatar.bytecode;
 
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
 /**
  * Application test
  */
-public class AppTest {
+class AppTest {
+
+  /**
+   * Issue: Add at least one assertion to this test case.
+   *
+   * Solution: Inserted assertion to check whether the execution of the main method in {@link App}
+   * throws an exception.
+   */
 
   @Test
-  public void test() {
-    App.main(new String[]{});
+  void shouldExecuteApplicationWithoutException() {
+    assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 }