Add `DateTime.Should().Be(DateTime?)` and `DateTimeOffset.Should().Be(DateTimeOffset?)` overloads

Description

Some overloads of Be for primitive types have a nullable version to facilitate calling them against standard and nullable versions of the value. For example:

Normal:

Nullable:

However, these nullable overloads do not exist currently for both DateTime and DateTimeOffset.

I propose the overloads be added to help with testing these types of properties and for consistency in the FluentAssertions API.

Expected behavior:

2 overloads be added, one for DateTime and another for DateTimeOffset, allowing to compare (Be) with their nullable counterparts. When the values are null, the assertion should obviously fail.

Actual behavior:

Overloads do not exist, forcing extra logic inside assertions to get the .Value.

Versions

• FluentAssertions 5.10.3
• Net Core 3.1

[dennisdoomen]

Ah, yes, now I get it.

[facundo91]

To mimic the behavior of NumericAssertions. I have added the cases marked in bold to DateTimeAssertions and DateTimeOffsetAssertions. Below examples are for Datetime, but same logic was followed for DatetimeOffset.

subject.Be(expected)

subject	expected	result
16/11/2020	16/11/2020	true
16/11/2020	null	false
null	16/11/2020	false
null	null	true

subject.NotBe(expected)

subject	expected	result
16/11/2020	16/11/2020	false
16/11/2020	null	true
null	16/11/2020	true
null	null	false