fix: prevent 'cd ..' from moving above root directory

Author: Harushii16

src/main/java/com/mycmd/commands/CdCommand.java

@@ -7,14 +7,36 @@
 public class CdCommand implements Command {
     @Override
     public void execute(String[] args, ShellContext context) {
+        // No argument -> print current directory
         if (args.length == 0) {
             System.out.println(context.getCurrentDir().getAbsolutePath());
             return;
         }
-        File newDir = new File(args[0]);
+
+        String dir = args[0];
+
+        // Normalize "cd.." without space to ".."
+        if (dir.equals("cd..")) {
+            dir = "..";
+        }
+
+        File newDir = new File(dir);
+
+        // If relative path, resolve from current directory
         if (!newDir.isAbsolute()) {
-            newDir = new File(context.getCurrentDir(), args[0]);
+            newDir = new File(context.getCurrentDir(), dir);
+        }
+
+        // Handle "cd .." when already at root
+        if (dir.equals("..")) {
+            File parent = context.getCurrentDir().getParentFile();
+            if (parent == null) {
+                System.out.println("Already at the root directory.");
+                return;
+            }
+            newDir = parent;
         }
+
         if (newDir.exists() && newDir.isDirectory()) {
             context.setCurrentDir(newDir);
         } else {