✅ fix test for when indy_credx is installed or not

Signed-off-by: ff137 <[email protected]>

aries_cloudagent/revocation/models/tests/test_issuer_rev_reg_record.py

@@ -198,7 +198,11 @@ def handle(self):
             }
         )
         rev_reg_delta = credx_module.RevocationRegistryDelta.load(rev_reg_delta_json)
-        rev_reg_delta.to_json.return_value = rev_reg_delta_json
+
+        if hasattr(rev_reg_delta.to_json, "return_value"):
+            # if indy_credx is not installed, then we're dealing with a mocked method
+            # therefore, set the return_value to avoid MagicMock being passed to json.loads
+            rev_reg_delta.to_json.return_value = rev_reg_delta_json
 
         TEST_GENESIS_TXN = "test_genesis_txn"
         rec = IssuerRevRegRecord(