@@ -0,0 +1,137 @@
+# @file
+#
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+"""Tests for the authenticode_transplant script."""
+
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+
+
+class TestAuthenticodeTransplant(unittest.TestCase):
+    """Test cases for authenticode transplant functionality."""
+
+    def setUp(self) -> None:
+        """Set up test fixtures."""
+        self.test_dir = tempfile.mkdtemp()
+
+    def tearDown(self) -> None:
+        """Clean up test fixtures."""
+        # Clean up test files if they exist
+        for file in os.listdir(self.test_dir):
+            os.remove(os.path.join(self.test_dir, file))
+        os.rmdir(self.test_dir)
+
+    def test_help_message(self) -> None:
+        """Test that the help message can be generated without errors."""
+        try:
+            result = subprocess.run(
+                [sys.executable, "scripts/authenticode_transplant.py", "--help"],
+                cwd="/home/runner/work/secureboot_objects/secureboot_objects",
+                capture_output=True,
+                text=True,
+                timeout=10
+            )
+            self.assertEqual(result.returncode, 0)
+            self.assertIn("Transplant Authenticode signature", result.stdout)
+            self.assertIn("source_pe", result.stdout)
+            self.assertIn("target_pe", result.stdout)
+            self.assertIn("output_pe", result.stdout)
+            self.assertIn("--force", result.stdout)
+            self.assertIn("--debug", result.stdout)
+        except subprocess.TimeoutExpired:
+            self.fail("Help command timed out")
+
+    def test_missing_arguments(self) -> None:
+        """Test that missing arguments are handled properly."""
+        try:
+            result = subprocess.run(
+                [sys.executable, "scripts/authenticode_transplant.py"],
+                cwd="/home/runner/work/secureboot_objects/secureboot_objects",
+                capture_output=True,
+                text=True,
+                timeout=10
+            )
+            self.assertNotEqual(result.returncode, 0)  # Should fail with missing args
+        except subprocess.TimeoutExpired:
+            self.fail("Command with no args timed out")
+
+    def test_nonexistent_source_file(self) -> None:
+        """Test handling of non-existent source file."""
+        target_file = os.path.join(self.test_dir, "target.exe")
+        output_file = os.path.join(self.test_dir, "output.exe")
+
+        # Create a dummy target file
+        with open(target_file, 'wb') as f:
+            f.write(b"dummy content")
+
+        try:
+            result = subprocess.run(
+                [sys.executable, "scripts/authenticode_transplant.py",
+                 "/nonexistent/source.exe", target_file, output_file],
+                cwd="/home/runner/work/secureboot_objects/secureboot_objects",
+                capture_output=True,
+                text=True,
+                timeout=10
+            )
+            self.assertNotEqual(result.returncode, 0)
+            self.assertIn("Source PE file not found", result.stderr)
+        except subprocess.TimeoutExpired:
+            self.fail("Command with nonexistent source timed out")
+
+    def test_nonexistent_target_file(self) -> None:
+        """Test handling of non-existent target file."""
+        source_file = os.path.join(self.test_dir, "source.exe")
+        output_file = os.path.join(self.test_dir, "output.exe")
+
+        # Create a dummy source file
+        with open(source_file, 'wb') as f:
+            f.write(b"dummy content")
+
+        try:
+            result = subprocess.run(
+                [sys.executable, "scripts/authenticode_transplant.py",
+                 source_file, "/nonexistent/target.exe", output_file],
+                cwd="/home/runner/work/secureboot_objects/secureboot_objects",
+                capture_output=True,
+                text=True,
+                timeout=10
+            )
+            self.assertNotEqual(result.returncode, 0)
+            self.assertIn("Target PE file not found", result.stderr)
+        except subprocess.TimeoutExpired:
+            self.fail("Command with nonexistent target timed out")
+
+    def test_debug_flag(self) -> None:
+        """Test that debug flag is accepted."""
+        source_file = os.path.join(self.test_dir, "source.exe")
+        target_file = os.path.join(self.test_dir, "target.exe")
+        output_file = os.path.join(self.test_dir, "output.exe")
+
+        # Create dummy files
+        with open(source_file, 'wb') as f:
+            f.write(b"dummy content")
+        with open(target_file, 'wb') as f:
+            f.write(b"dummy content")
+
+        try:
+            result = subprocess.run(
+                [sys.executable, "scripts/authenticode_transplant.py",
+                 "--debug", source_file, target_file, output_file],
+                cwd="/home/runner/work/secureboot_objects/secureboot_objects",
+                capture_output=True,
+                text=True,
+                timeout=10
+            )
+            # Should fail because these aren't real PE files, but debug flag should be accepted
+            self.assertNotEqual(result.returncode, 0)
+        except subprocess.TimeoutExpired:
+            self.fail("Command with debug flag timed out")
+
+
+if __name__ == "__main__":
+    unittest.main()