Mapping from Interface to concrete class no longer works as expected

[jgilm]

In Automapper 4.2.1 mapping from an Interface to a concrete class worked so that if a null property defined as an Interface would map to a concrete class as null.

In Automapper 5.0.2 a null interface property maps to a default constructed concrete class.

This is a breaking issue for my application. I have a lot of interface properties on source classes mapping to concrete class properties in the destination class.

Expectation:
I would expect that null properties on the source would map to null properties on the destination.

To test:
Gist

• Make new console app, paste in gist
• install Automapper 4.2.1 package and run console app. Test passes.
• install Automapper 5.0.2 package and run console app. Test fails.

Although test is a console app, issue also occurs in a UWP app.

4.2.1 output:

5.0.2 output:

[jgilm]

Another person found this same issue and posted it on StackOverflow, but no answers.

[alex-davidson]

Excellent, thank you! This issue was blocking our upgrade from Automapper 3.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.