context Requirement {
	
	constraint IdIsUnique {
		check : Requirement.all.select(r|r.id = self.id).size() = 1
	}
	
}

context TraceLink {
	
	constraint SuspectLink {
	
		check {	
			var requirement = Requirement.all.selectOne(r|r.id = self.from.id);
			var test = Test.all.selectOne(t|t.id = self.to.id);
			
			return requirement.version = self.from.version 
				and test.version = self.to.version;
		}
		
		message : "Link from " + self.from.id + " to " + self.to.id + " is suspect"
		
	}
	
}