Test the case where the package has the _test suffix.
Prior to patch:
$ go generate
$ go test
# github.com/fishybell/mock/mockgen/internal/tests/mock_in_test_package_test [github.com/fishybell/mock/mockgen/internal/tests/mock_in_test_package.test]
./mock_test.go:36:44: undefined: User
./mock_test.go:38:21: undefined: User
FAIL github.com/fishybell/mock/mockgen/internal/tests/mock_in_test_package [build failed]
With this patch applied:
$ go generate
$ go test
ok github.com/fishybell/mock/mockgen/internal/tests/mock_in_test_package 0.031s