data-driven TLV unit data test support

While we do have the _test_de_encode data driven tests for file
definitions, we don't yet have something similar for derived classes of
BER_TLV_IE. This means that TLVs used outside of the filesystem context
(for example, decoding the SELECT/STATUS response, but also eUICC and
other stuff) do not yet have test coverage.

This commit just adds the related test code, but no test data yet.

Related: OS#6317
Change-Id: Ied85f292bb57fde11dc188be84e3384dc3ff1601

tests/test_tlvs.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+
+# (C) 2023 by Harald Welte <laforge@osmocom.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+import logging
+
+from pySim.utils import b2h, h2b, all_subclasses
+from pySim.tlv import *
+
+import pySim.iso7816_4
+import pySim.ts_102_221
+import pySim.ts_102_222
+import pySim.ts_31_102
+import pySim.ts_31_103
+import pySim.ts_51_011
+import pySim.sysmocom_sja2
+import pySim.gsm_r
+import pySim.cdma_ruim
+
+if 'unittest.util' in __import__('sys').modules:
+    # Show full diff in self.assertEqual.
+    __import__('sys').modules['unittest.util']._MAX_LENGTH = 999999999
+
+def get_qualified_name(c):
+    """return the qualified (by module) name of a class."""
+    return "%s.%s" % (c.__module__, c.__name__)
+
+class TLV_IE_Test(unittest.TestCase):
+    maxDiff = None
+
+    @classmethod
+    def get_classes(cls):
+        """get list of TLV_IE sub-classes."""
+        return all_subclasses(TLV_IE)
+
+    @classmethod
+    def setUpClass(cls):
+        """set-up method called once for this class by unittest framework"""
+        cls.classes = cls.get_classes()
+
+    def test_decode_tlv(self):
+        """Test the decoder for a TLV_IE.  Requires the given TLV_IE subclass
+        to have a '_test_decode' attribute, containing a list of tuples. Each tuple
+        is a 2-tuple (hexstring, decoded_dict).
+        """
+        for c in self.classes:
+            name = get_qualified_name(c)
+            if hasattr(c, '_test_decode'):
+                for t in c._test_decode:
+                    with self.subTest(name, test_decode=t):
+                        inst = c()
+                        encoded = t[0]
+                        decoded = { camel_to_snake(c.__name__): t[1] }
+                        context = t[2] if len(t) == 3 else {}
+                        logging.debug("Testing decode of %s", name)
+                        inst.from_tlv(h2b(encoded), context=context)
+                        re_dec = inst.to_dict()
+                        self.assertEqual(decoded, re_dec)
+
+    def test_encode_tlv(self):
+        """Test the encoder for a TLV_IE.  Requires the given TLV_IE subclass
+        to have a '_test_encode' attribute, containing a list of tuples. Each tuple
+        is a 2-tuple (hexstring, decoded_dict).
+        """
+        for c in self.classes:
+            name = get_qualified_name(c)
+            if hasattr(c, '_test_encode'):
+                for t in c._test_encode:
+                    with self.subTest(name, test_encode=t):
+                        inst = c()
+                        encoded = t[0]
+                        decoded = { camel_to_snake(c.__name__): t[1] }
+                        context = t[2] if len(t) == 3 else {}
+                        logging.debug("Testing encode of %s", name)
+                        inst.from_dict(decoded)
+                        re_enc = b2h(inst.to_tlv(context))
+                        self.assertEqual(encoded.upper(), re_enc.upper())
+
+    def test_de_encode_tlv(self):
+        """Test the decoder and encoder for a TLV_IE.  Performs first a decoder
+        test, and then re-encodes the decoded data, comparing the re-encoded data with the
+        initial input data.
+
+        Requires the given TLV_IE subclass to have a '_test_de_encode' attribute,
+        containing a list of tuples. Each tuple is a 2-tuple (hexstring, decoded_dict).
+        """
+        for c in self.classes:
+            name = get_qualified_name(c)
+            if hasattr(c, '_test_de_encode'):
+                for t in c._test_de_encode:
+                    with self.subTest(name, test_de_encode=t):
+                        inst = c()
+                        encoded = t[0]
+                        decoded = { camel_to_snake(c.__name__): t[1] }
+                        context = t[2] if len(t) == 3 else {}
+                        logging.debug("Testing decode of %s", name)
+                        inst.from_tlv(h2b(encoded), context=context)
+                        re_dec = inst.to_dict()
+                        self.assertEqual(decoded, re_dec)
+                        logging.debug("Testing re-encode of %s", name)
+                        re_enc = b2h(inst.to_tlv(context=context))
+                        self.assertEqual(encoded.upper(), re_enc.upper())
+
+
+if __name__ == '__main__':
+    logger = logging.getLogger()
+    logger.setLevel(logging.DEBUG)
+    unittest.main()