Make `@admin.register` fixer skip duplicately named admin classes

[adamchainz]

Currently the fixer does this:

 class BookAdmin(admin.ModelAdmin):
     ...

 class BookAdmin(admin.ModelAdmin):
     ...

- admin.site.register(Book, BookAdmin)

The registration is unsafely removed.

[UnknownPlatypus]

Hum that's weird, I tried to add the following test and it passed :thinking:

def test_duplicated_class_definition():
    check_transformed(
        """\
        from django.contrib import admin

        class BookAdmin(admin.ModelAdmin):
            pass

        class BookAdmin(admin.ModelAdmin):
            pass

        admin.site.register(Book, BookAdmin)
        """,
        """\
        from django.contrib import admin

        @admin.register(Book)
        class BookAdmin(admin.ModelAdmin):
            pass

        @admin.register(Book)
        class BookAdmin(admin.ModelAdmin):
            pass

        """,
    )

[adamchainz]

Oh, thank you for trying. I simplified it out of a project I was just helping out on. I will check to see if there are any other relevant details I missed.

[adamchainz]

Right, the failure was actually:

 class BookAdmin(admin.ModelAdmin):
     ...

- admin.site.register(Book, BookAdmin)

 class BookAdmin(admin.ModelAdmin):
     ...  

I’m going to adjust the fixer to bail when a duplicate definition is found.