1 files changed, 15 insertions, 1 deletions
diff --git a/tests/test_pem.py b/tests/test_pem.py
index 952ec79..61a66fc 100644
--- a/tests/test_pem.py
+++ b/tests/test_pem.py
@@ -17,7 +17,7 @@
 
 import unittest
 
-from rsa._compat import b
+from rsa._compat import b, is_bytes
 from rsa.pem import _markers
 import rsa.key
 
@@ -72,3 +72,17 @@ class TestBytesAndStrings(unittest.TestCase):
         key = rsa.key.PrivateKey.load_pkcs1(private_key_pem.encode('ascii'))
         self.assertEqual(prime1, key.p)
         self.assertEqual(prime2, key.q)
+
+
+class TestByteOutput(unittest.TestCase):
+    """Tests that PEM and DER are returned as bytes."""
+
+    def test_bytes_public(self):
+        key = rsa.key.PublicKey.load_pkcs1_openssl_pem(public_key_pem)
+        self.assertTrue(is_bytes(key.save_pkcs1(format='DER')))
+        self.assertTrue(is_bytes(key.save_pkcs1(format='PEM')))
+
+    def test_bytes_private(self):
+        key = rsa.key.PrivateKey.load_pkcs1(private_key_pem)
+        self.assertTrue(is_bytes(key.save_pkcs1(format='DER')))
+        self.assertTrue(is_bytes(key.save_pkcs1(format='PEM')))