BuildingSmart IFCRail changes to BIMTester (#1309)

* Add a way to validate the IFC file in BIMTester

* Fix an issue in Report where only the first error was shown

* Fix the usage of Schema in BIMTester

* Add Aggreation steps to BIMTester

src/ifcbimtester/bimtester/reports.py

@@ -93,9 +93,7 @@ class ReportGenerator:
             step["result"] = {}
             step["result"]["status"] = "skipped"
             step["result"]["duration"] = 0
-            step["result"][
-                "error_message"
-            ] = "This requirement has been skipped due to a previous failing step."
+            step["result"]["error_message"] = "This requirement has been skipped due to a previous failing step."
         elif step["result"]["status"] == "undefined":
             step["result"] = {}
             step["result"]["status"] = "undefined"
@@ -108,14 +106,12 @@ class ReportGenerator:
             "is_success": step["result"]["status"] == "passed",
             "is_unspecified": step["result"]["status"] == "undefined",
             "is_skipped": step["result"]["status"] == "skipped",
-            "error_message": None
-            if step["result"]["status"] == "passed"
-            else step["result"]["error_message"],
+            "error_message": None if step["result"]["status"] == "passed" else step["result"]["error_message"],
         }
 
-        # TODO: there is probably a better way of doing this
-        if isinstance(data["error_message"], list):
-            data["error_message"] = data["error_message"][1]
+        # Remove the first "Assertion Failed" message
+        if isinstance(data["error_message"], list) and data["error_message"]:
+            data["error_message"].pop(0)
         return data
 
     def get_template_strings(self):