Here are my requirements for unit testing:
This seems like reasonable requirements. However, a problem always arises when I need to use methods such as assertEquals
on objects as these requires that the equals
method is overridden. The equals
method would have to be implemented in production classes but is actually only used for testing. This becomes even worse when good coding practices dictates that if equals
is overridden, then should hashCode
also be implemented resulting in even more unused production code that clutters the production classes.
Here is a simple example with a User
model (IntelliJ autoimplemented equals
and hashCode
)
public class User
{
public long id;
public long companyId;
public String name;
public String email;
public long version;
@Override
public boolean equals(Object o)
{
if(this == o) return true;
if(o == null || getClass() != o.getClass()) return false;
User user = (User) o;
if(companyId != user.companyId) return false;
if(id != user.id) return false;
if(version != user.version) return false;
if(!email.equals(user.email)) return false;
if(!name.equals(user.name)) return false;
return true;
}
@Override
public int hashCode()
{
int result = (int) (id ^ (id >>> 32));
result = 31 * result + (int) (companyId ^ (companyId >>> 32));
result = 31 * result + name.hashCode();
result = 31 * result + email.hashCode();
result = 31 * result + (int) (version ^ (version >>> 32));
return result;
}
}
As it can be seen, equals
and hashCode
takes up a lot of space and clutters the class.
One solution to the problem could be to create a class, UserTester
, which could have an assertUserEquals
method that could be used instead of eg. JUnit's assertEquals
.
Another solution could be to create a UserComparator
. However, it does not seem like JUnit have any assertEquals
that takes a Comparator
.
What is best practices on this point?
Uniutils has a perfect reflection equals method you can use for unit testing. This way your production code remains clear from all this test stuff.
public class User {
private long id;
private String first;
private String last;
public User(long id, String first, String last) {
this.id = id;
this.first = first;
this.last = last;
}
}
Later in test:
User user1 = new User(1, "John", "Doe");
User user2 = new User(1, "John", "Doe");
assertReflectionEquals(user1, user2);
If you're using Mockito it has it's own means to do the same thing:
Mockito.verify(userDeleter).delete(Mockito.refEq(user));