Ignore internal properties in ShouldBeEquivalentTo

Question

Is there a way to ignore internal properties of a class when doing ShouldBeEquivalentTo?

For example, in the class below I want to exclude the MetaData property from the object graph comparison.

public class SomeObject 
{
    Public string SomeString { get; set; }
    internal MetaData MetaData { get; set; }
}

I would prefer to not use

someObject.ShouldBeEquivalentTo(someOtherObject, options =>     
    options.Excluding(info => info.SelectedMemberPath == "MetaData")

Because I might have more than 1 internal property and setting up this for all those properties would be tedious.

Answer 1

There is the IMemberSelectionRule interface in the FluentAssertions library:

Represents a rule that defines which members of the subject-under-test to include while comparing two objects for structural equality.

Implementing this interface allows to exclude all the internal properties at once (where IsAssembly property is true):

  internal class AllExceptNonPublicPropertiesSelectionRule : IMemberSelectionRule
  {
    public bool IncludesMembers
    {
      get { return false; }
    }

    public IEnumerable<SelectedMemberInfo> SelectMembers(
      IEnumerable<SelectedMemberInfo> selectedMembers,
      ISubjectInfo context,
      IEquivalencyAssertionOptions config)
    {
      return selectedMembers.Except(
        config.GetSubjectType(context)
          .GetNonPrivateProperties()
          .Where(p => p.GetMethod.IsAssembly)
          .Select(SelectedMemberInfo.Create));
    }
  }

Now the rule can be utilized in unit tests:

  someObject.ShouldBeEquivalentTo(someOtherObject, options => options.Using(
    new AllExceptNonPublicPropertiesSelectionRule()));