A way to generate file in a specific path for Mockito?

Question

I want to have all those mock files generated by Mockito (build_runner command) inside test/mock/** but it all goes to source path which is test/.

build.yaml

targets:   
    $default:     
        builders:       
            mockito|mockBuilder:         
            enabled: true         
            generate_for:           
                - test/**
                - integration_test/**
            dev_options: # I also try with options
            build_extensions:
                '{{file}}.dart':
                    - 'test/mocks/{{file}}.mocks.dart'
                    - 'integration_test/mocks/{{file}}.mocks.dart'

I can't find any other examples of doing it. I also did this by looking at documentation from build documentatoin.