  Industry 4.0 represents a major technological shift that has the potential to
transform the manufacturing industry, making it more efficient, productive, and
sustainable. Smart farming is a concept that involves the use of advanced
technologies to improve the efficiency and sustainability of agricultural
practices. Industry 4.0 and smart farming are closely related, as many of the
technologies used in smart farming are also used in Industry 4.0. Digital twins
have the potential for cost-effective software development of such
applications. With our Digital Twin Prototype approach, all sensor interfaces
are integrated into the development process, and their inputs and outputs of
the emulated hardware match those of the real hardware. The emulators respond
to the same commands and return identically formatted data packages as their
real counterparts, making the Digital Twin Prototype a valid source of a
digital shadow, i.e. the Digital Twin Prototype is a prototype of the physical
twin and can replace it for automated testing of the digital twin software. In
this paper, we present a case study for employing our Digital Twin Prototype
approach to automated testing of software for improving the making of silage
with a smart farming application. Besides automated testing with continuous
integration, we also discuss continuous deployment of modular Docker containers
in this context.
