The interview was an automated, remote technical assessment focused on practical skills. You are required to share your entire screen for the duration of the test, and failing to do so disqualifies the application. The assessment prohibits the use of LLMs such as ChatGPT and Cursor, but it allows standard internet searches. The main task involves downloading provided Dockerfiles and fixing a broken environment configuration to make a legacy codebase run successfully.

You are given an incomplete Dockerfile.candidate and a base image containing a 2019 commit of the black code formatter repository. The task is to write Conda commands within the Dockerfile to set up an environment named testbed. You must install the correct Python version and dependencies so that pytest tests/test_black.py runs successfully. You are strictly limited to using Conda (no Poetry, uv, etc.).