WithCustomMessage does not give a custom message when being used with IsTrue()

[janvdpol]

Expected Behavior

The following line
Check.WithCustomMessage("It's false!").That(false).IsTrue();
should output "It's false"

Current Behavior

The following line
Check.WithCustomMessage("It's false!").That(false).IsTrue();
should output "expected [false] but was [true]" (or something similar)

Possible Solution

Workaround
Check.WithCustomMessage("It's false!").That(false).IsEqualTo(true);
This will output "It's false"

Code that reproduce the issue

....
Check.WithCustomMessage("It's false!").That(false).IsTrue(); 
...

Context

I have a method that's returning true or false, in case of a false i would like to provide more information why it is false.

Your Environment

• Version used: 2.6.0
• Framework version: Core 2.2
• Link to your project: -

[dupdob]

Thanks for reporting this issue with great details.

1. I have been able to reproduce this issue and I confirm this is a bug (see explanation below)
2. I will work on a fix and will publish a beta (with the fix) in the coming days
3. As a workaround, you can use IsFalse and negating your condition. It will work as expected:

Check.WithCustomMessage("It's false!").That(!false).IsFalse();

Bug explanation: IsTrue is translated to Not.IsFalse (internally), and your issue revealed a bug in Not: any custom message is lost when using Not.