diff --git a/src/ifcbimtester/bimtester/features/steps/aggregation.py b/src/ifcbimtester/bimtester/features/steps/aggregation.py
new file mode 100644
index 0000000000..f3bbec37b8
--- /dev/null
+++ b/src/ifcbimtester/bimtester/features/steps/aggregation.py
@@ -0,0 +1,114 @@
+from behave import step, given, when, then, use_step_matcher
+
+from utils import IfcFile
+
+use_step_matcher("parse")
+@step(u"There must be exactly {number} {ifc_class} element")
+@step(u"There must be exactly {number} {ifc_class} elements")
+def step_impl(context, number, ifc_class):
+    num = len(IfcFile.get().by_type(ifc_class))
+    assert num == int(number), "Could not find {} elements of {}. Found {} element(s).".format(number, ifc_class, num)
+
+@given(u'a set of specific related elements')
+def step_impl(context):
+    model = getattr(context, "model", None)
+    if not model:
+        context.model = TableModel()
+    for row in context.table:
+        context.model.add_row(row["RelatedObjects"], row["RelatingGroup"])
+
+@given(u'a set of specific related elements taken from the file "{path_file}"')
+def step_impl(context, path_file):
+    import csv
+    model = getattr(context, "model", None)
+    if not model:
+        context.model = TableModel()
+    with open(path_file, encoding="utf-8") as csvfile:
+        reader = csv.DictReader(csvfile)
+        for row in reader:
+            context.model.add_row(row["RelatedObjects"], row["RelatingGroup"])
+
+@then(u'there must be exactly a number of {ifc_class} equals to the number of distinct row value')
+def step_impl(context, ifc_class):
+    try:
+        context.execute_steps(u"""
+            then There must be exactly {number} {ifc_class} elements
+            """.format(ifc_class=ifc_class, number=context.model.get_count_distinct_values()))
+    except AssertionError as error:
+        str_error = str(error)
+        assert False, str_error[:str_error.find("Traceback")]
+    assert True
+
+@then(u'there is a relationship {ifc_class} with {left_attribute} and {right_attribute} between the two elements of each row')
+def step_impl(context, ifc_class, left_attribute, right_attribute):
+    rows = context.model.rows
+    elements = IfcFile.by_type(ifc_class)
+    errors = []
+    for key, value in rows.items():
+        found = False
+        for element in elements:
+            if any(x.Name == key for x in getattr(element, left_attribute))\
+                and getattr(element, right_attribute).Name == value:
+                found = True
+        if not found:
+            errors.append(f'The row ({key}, {value}) does not have the relationship.')
+    assert not errors, "Errors occured:\n{}".format("\n".join(errors))
+
+use_step_matcher("re")
+@step("all IfcGroup must be linked to a type in the list (?P<linked_ifc_classes>.*)")
+def step_impl(context, linked_ifc_classes):
+    groups = IfcFile.by_type("IfcGroup")
+    errors = []
+    for group in groups:
+        if not hasattr(group, "IsGroupedBy"):
+            errors.append(f'The element "{group.Name}" has no "IsGroupedBy" attribute.')
+        else:
+            for grouped_by in getattr(group, "IsGroupedBy"):
+                if not hasattr(grouped_by, "RelatedObjects"):
+                    errors.append(f'The element "{grouped_by.Name}" has no "RelatedObjects" attribute.')
+                else:
+                    for related_object in getattr(grouped_by, "RelatedObjects"):
+                        found = False
+                        for linked_ifc_class in linked_ifc_classes.split(","):
+                            if(related_object.is_a(linked_ifc_class)):
+                                found = True
+                        if not found:
+                            errors.append(f'The element "{related_object.Name}" does not have the right associated type.') 
+    assert not errors, "Errors occured:\n{}".format("\n".join(errors))
+
+@then(u'there is an element of type (?P<ifc_types>.*) with a (?P<attribute_name>.*) attribute for each row key')
+def step_impl(context, ifc_types, attribute_name):
+    check_if_element_exists_by_types_with_attribute_name(ifc_types, attribute_name, context.model.rows.keys())
+
+@then(u'there is an element of type (?P<ifc_types>.*) with a (?P<attribute_name>.*) attribute for each row value')
+def step_impl(context, ifc_types, attribute_name):
+    values = set(context.model.rows.values())
+    check_if_element_exists_by_types_with_attribute_name(ifc_types, attribute_name, values)
+
+def check_if_element_exists_by_types_with_attribute_name(ifc_types, attribute_name, attribute_values):
+    errors = []
+    # retrieve all elements of that type
+    elements = IfcFile.by_types(ifc_types)
+    # loop
+    for attribute_value in attribute_values:
+        found = False
+        for element in elements:
+            if hasattr(element, attribute_name) and getattr(element, attribute_name) == attribute_value:
+                found = True
+        if not found:
+            errors.append(f'An element with {attribute_name} attribute "{attribute_value}" was not found.')
+    assert not errors, "Errors occured:\n{}".format("\n".join(errors))
+
+class TableModel(object):
+    """This class represents a table of data."""
+    def __init__(self):
+        self.rows = dict()
+
+    def add_row(self, related, relating):
+        self.rows[related] = relating
+        
+    def get_count(self):
+        return len(self.rows)
+    
+    def get_count_distinct_values(self):
+        return len(set(self.rows.values()))
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