diff --git a/primitives/test_authenticated_encryption.py b/primitives/test_authenticated_encryption.py
index 0f7c1ac..8d78f36 100644
--- a/primitives/test_authenticated_encryption.py
+++ b/primitives/test_authenticated_encryption.py
@@ -1,5 +1,11 @@
 import pytest
-from authenticated_encryption import generate_key, AESGCM_encrypt, _bytes_to_hex_string
+from authenticated_encryption import (
+    generate_key, AESGCM_encrypt,
+    _bytes_to_hex_string,
+    AESGCM_decrypt,
+    _hex_string_to_bytes,
+    _to_bytes_like
+)
 
 def test_generate_key_valid_lengths():
     for key_length in [128, 192, 256]:
@@ -21,21 +27,43 @@ def test_AESGCM_encrypt():
     key = '941e058419564953ec4292aab10728b0f2c03eae5b89dc29abf77406ee051d29'
     secret = 'my_secret_data'
     encrypted_data = AESGCM_encrypt("", key, secret)
+    nonce = encrypted_data['nonce']
+    decrypted = AESGCM_decrypt("", key, encrypted_data['chiper'], nonce)
     assert encrypted_data
-
-"""
-def test_AESGCM_decrypt():
-    key = '000102030405060708090a0b0c0d0e0f'
-    secret = 'my_secret_data'
-    unencrypted_data = 'unencrypted_data'
-    encrypted_data = AESGCM_encrypt("", key, secret)
-
-    decrypted_data = AESGCM_decrypt("", key, encrypted_data)
-    assert decrypted_data == secret
-"""
+    assert decrypted['message'] == secret
 
 def test_bytes_to_hex_string():
     byte_key = b'\x00\x01\x02\x03\x04\x05'
     expected_hex_string = '000102030405'
     hex_string = _bytes_to_hex_string(byte_key)
-    assert hex_string == expected_hex_string
\ No newline at end of file
+    assert hex_string == expected_hex_string
+
+def test_hex_string_to_bytes():
+    hex_string = '48656c6c6f20776f726c64'
+    expected_bytes = b'Hello world'
+    assert _hex_string_to_bytes(hex_string) == expected_bytes
+
+    hex_string = ''
+    expected_bytes = b''
+    assert _hex_string_to_bytes(hex_string) == expected_bytes
+
+    hex_string = 'zzzz'
+    with pytest.raises(ValueError):
+        _hex_string_to_bytes(hex_string)
+
+def test_to_bytes_like():
+    string_data = 'Hello world'
+    expected_bytes = b'Hello world'
+    assert _to_bytes_like(string_data) == expected_bytes
+
+    list_data = [72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
+    expected_bytes = b'Hello world'
+    assert _to_bytes_like(list_data) == expected_bytes
+
+    tuple_data = (72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100)
+    expected_bytes = b'Hello world'
+    assert _to_bytes_like(tuple_data) == expected_bytes
+
+    invalid_data = 123
+    with pytest.raises(TypeError):
+        _to_bytes_like(invalid_data)
\ No newline at end of file