src/xunit.v3.assert.compat/README.md
These projects are here to validate compatibility (mostly backward), since the assertion library currently has several optionally enabled features.
The minimum target framework support for the assertion library is:
The compatibility projects are mostly compiled with one or more of the minimum target frameworks, except for xunit.v3.assert.all-on which adds additional targets for newer versions of target frameworks as they become available (to help ensure that source-based consumers don't encounter new issues from newer target frameworks).
The minimum C# language versions is 7.3, as this aligns with the default when building for net472. Adding support for XUNIT_NULLABLE requires a minimum C# language version of 9, as this is what's required for our nullability annotations.