Description

StringAssertions.StartWith throws an ArgumentException when asserting that a string starts with the empty string.

This makes it so that the assertions in one of the tips are not equivalent when expectedPrefix is empty.

Complete minimal example reproducing the issue

string actual = "abc";
string expectedPrefix = "";

actual.StartsWith(expectedPrefix).Should().BeTrue();
actual.Should().StartWith(expectedPrefix);

Expected behavior:

Both assertions to pass.

Actual behavior:

The first assertion passes, but the second throws an ArgumentException with message

Cannot compare start of string with empty string. (Parameter 'expected')

Versions

• Fluent Assertions: 5.10.3
• .NET runtime: .NET Core 3.1

Additional Information

StringAssertions.EndWith and String.EndsWith are inconsistent in the same way.