diff --git a/megaradrp/products.py b/megaradrp/products.py
index 9faf12ea..1dca6f56 100644
--- a/megaradrp/products.py
+++ b/megaradrp/products.py
@@ -19,7 +19,6 @@
 
 """Products of the Megara Pipeline"""
 
-
 '''
     RAW_BIAS DataFrameType
     RAW_DARK DataFrameType
@@ -64,13 +63,10 @@ class MasterSensitivity(MEGARAProductFrame):
 
 
 class TraceMap(DataProductType):
-
     def __init__(self, default=None):
-        super(TraceMap, self).__init__(
-            ptype=dict, default=default)
-
-    def __numina_dump__(self, obj, where):
+        super(TraceMap, self).__init__(ptype=dict, default=default)
 
+    def _datatype_dump(self, obj, where):
         filename = where.destination + '.yaml'
 
         with open(filename, 'w') as fd:
@@ -78,9 +74,10 @@ def __numina_dump__(self, obj, where):
 
         return filename
 
-    def __numina_load__(tag, obj):
-
-        with open(obj, 'r') as fd:
-            traces = yaml.load(fd)
-
-        return traces
\ No newline at end of file
+    def _datatype_load(self, obj):
+        try:
+            with open(obj, 'r') as fd:
+                traces = yaml.load(fd)
+        except IOError as e:
+            raise e
+        return traces
diff --git a/megaradrp/tests/test_products.py b/megaradrp/tests/test_products.py
new file mode 100644
index 00000000..8db14923
--- /dev/null
+++ b/megaradrp/tests/test_products.py
@@ -0,0 +1,66 @@
+#
+# Copyright 2015 Universidad Complutense de Madrid
+#
+# This file is part of Megara DRP
+#
+# Megara DRP 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 3 of the License, or
+# (at your option) any later version.
+#
+# Megara DRP 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 Megara DRP.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+from megaradrp.products import TraceMap
+from tempfile import NamedTemporaryFile
+import pytest
+import yaml
+
+@pytest.mark.xfail
+def test_fail_traceMap(benchmark=None):
+    my_obj = TraceMap()
+    my_obj._datatype_load('')
+
+def test_load_traceMap(benchmark=None):
+    data = dict(A = 'a',
+                B = dict(C = 'c',
+                         D = 'd',
+                         E = 'e',)
+                )
+
+    my_obj = TraceMap()
+    my_file = NamedTemporaryFile()
+    with open(my_file.name, 'w') as fd:
+        yaml.dump(data, fd)
+    my_open_file = my_obj._datatype_load(my_file.name)
+    assert (my_open_file == {'A': 'a', 'B': {'C': 'c', 'E': 'e', 'D': 'd'}})
+
+
+def test_dump_traceMap(benchmark=None):
+    class aux(object):
+        def __init__(self, destination):
+            self.destination = destination
+
+    data = dict(A = 'a',
+                B = dict(C = 'c',
+                         D = 'd',
+                         E = 'e',)
+                )
+
+    my_obj = TraceMap()
+    my_file = NamedTemporaryFile()
+    work_env = aux(my_file.name)
+    my_open_file = my_obj._datatype_dump(data, work_env)
+    with open(my_open_file, 'r') as fd:
+        traces = yaml.load(fd)
+    assert (traces == {'A': 'a', 'B': {'C': 'c', 'E': 'e', 'D': 'd'}})
+
+if __name__ == "__main__":
+    test_load_traceMap()
+    test_dump_traceMap()
\ No newline at end of file