Replace several untested paths with _openssl_assert (#498)

* Replace several untested paths with _openssl_assert

* fix, these require a bool

* oop, fixed

* finish porting crypto.py

* typo

* yessssssss
diff --git a/tests/test_crypto.py b/tests/test_crypto.py
index e13f1e4..2febb95 100644
--- a/tests/test_crypto.py
+++ b/tests/test_crypto.py
@@ -2827,6 +2827,14 @@
         """
         self.assertRaises(Error, load_pkcs7_data, FILETYPE_PEM, b"foo")
 
+    def test_load_pkcs7_type_invalid(self):
+        """
+        If the type passed to :obj:`load_pkcs7_data`, :obj:`ValueError` is
+        raised.
+        """
+        with pytest.raises(ValueError):
+            load_pkcs7_data(object(), b"foo")
+
 
 class LoadCertificateTests(TestCase):
     """