Hugging Face Agent Course Practice Test

Non-determinism in tool outputs can cause test flakiness, where the same test sometimes passes and sometimes fails for reasons unrelated to the code being tested. The most reliable way to address this is to make tests deterministic. Use deterministic seeds for any pseudo-random processes so outputs are repeatable across runs. Mock or stub external tools and their responses so the agent interacts with a controlled, predictable interface rather than live tool variability. Normalize outputs to stable representations by removing or standardizing non-essential variability (such as timestamps, IDs, or formatting) and by presenting results in a canonical form (for example, sorting lists before comparison). Together, these practices keep tests focused on the agent’s logic and behavior, reducing false negatives. Rerunning until it passes isn’t robust because it hides real issues, and ignoring nondeterminism leads to unstable tests.