ASN.1: minor: add quotes around a datatype in an err string and

remove commented-out pyasn1 imports.

Signed-off-by: Sebastien Awwad <sebastien.awwad@gmail.com>

tests/test_asn1_convert.py

@@ -33,12 +33,6 @@
 # Dependency Imports
 import asn1crypto as asn1
 import asn1crypto.core as asn1_core
-'''
-import pyasn1
-import pyasn1.type.univ as pyasn1_univ
-import pyasn1.type.char as pyasn1_char
-import pyasn1.codec.der.encoder as pyasn1_der_encoder
-'''
 # TUF Imports
 import tuf
 import tuf.log

tuf/encoding/asn1_convert.py

@@ -656,8 +656,8 @@ def _structlike_dict_to_asn1(data, datatype):
         continue
       else:
         raise tuf.exceptions.ASN1ConversionError(
-            'In conversion to "' + str(datatype) + '", expected to find key ' +
-            element_name_py + ' in input data, but did not.  Keys in input '
+            'In conversion to "' + str(datatype) + '", expected to find key "' +
+            element_name_py + '" in input data, but did not.  Keys in input '
             'data: ' + str(data.keys()))
 
     debug('In conversion of dict to type ' + str(datatype) + ', recursing '