Be() and BeSameAs() are doing the same thing

Description

Both methods Be() and BeSameAs() are failing when testing equivalent objects in different instances.

As far as I can understand by the documentation only BeSameAs() should compare if two objects refer to the same object in memory, but actually both functions are doing so.

Documentation:

To assert that two objects are equal (through their implementation of Object.Equals), use

string otherObject = "whatever";
theObject.Should().Be(otherObject, "because they have the same values");
theObject.Should().NotBe(otherObject);

If you want to make sure two objects are not just functionally equal but refer to the exact same object in memory, use the following two methods.

theObject = otherObject;
theObject.Should().BeSameAs(otherObject);
theObject.Should().NotBeSameAs(otherObject);

Complete minimal example reproducing the issue

public class ProductRequestModel
{
    public string Name { get; set; }
    public bool Active { get; set; }
}

[Fact]
public void Should_Be()
{
	var product1 = new ProductRequestModel
	{
		Active = true,
		Name = "Produto",
	};

	var product2 = new ProductRequestModel
	{
		Active = true,
		Name = "Produto",
	};

	product1.Should().Be(product2);
}

[Fact]
public void Should_BeSameAS()
{
	var product1 = new ProductRequestModel
	{
		Active = true,
		Name = "Produto",
	};

	var product2 = new ProductRequestModel
	{
		Active = true,
		Name = "Produto",
	};

	product1.Should().BeSameAs(product2);
}

Expected behavior:

Shoud_Be(), should pass. Shoud_BeSameAs(), should fail.

Actual behavior:

Shoud_Be(), fails Shoud_BeSameAs(), fails

Versions

• Which version of Fluent Assertions are you using? v5.9.0
• Which .NET runtime and version are you targeting? .Net Core 2.2

Additional Information

My error message for Should_Be() is as follows:

  Message: 
    Expected product1 to be 
    
    HBSIS.MapaCompetencia.Tests.Integration.ProductRequestModel
    {
       Active = True
       Name = "Produto"
    }, but found 
    
    HBSIS.MapaCompetencia.Tests.Integration.ProductRequestModel
    {
       Active = True
       Name = "Produto"
    }.

The interesting part is that Be(), works as expected when comparing anonymous objects.

[jnyrup]

Be uses object.Equals() to compare whether your two identical instances ProductRequestModel are to be considered equal. As you haven’t overridden object.Equals() on ProductRequestModel your objects are compared for reference equality, which is why you experience identical behavior as BeSameAs.

To compare the two objects memberwise, you can use BeEquivalentTo.

product1.Should().BeEquivalentTo(product2);

[dennisdoomen]

I did some further research and discovered that apparently this happens due to C# own design of Object.Equals(). As stated here, it seems that the method in question gets overridden by anonymous types, “so that two instances of the same anonymous type are equal if and only if all their properties are equal”.

Yep. That’s why we have two methods. Sometimes people override Equals on a subset of the properties, so just using Be might not what you want. Just like you sometimes use Equals, == or ReferenceEquals for reasons.

I’m closing this issue since FA does exactly how it is documented and designed.