Docs - product feedback: Cannot use AutoDevOps with a Dockerfile for languages not supported by Herokuish
https://docs.gitlab.com/ee/topics/autodevops/#custom-dockerfile states that
If your project has a Dockerfile in the root of the project repo, Auto DevOps will build a Docker image based on the Dockerfile rather than using buildpacks.
While true, the implication is that this allows, for example, projects based on ASP.NET Core to be built via the AutoDevOps pipeline.
However the AutoDevOps test stage does not abide by this convention established in the build stage.