Test Split Outputs Warning: “Error Reading Historical Timing Data: File Does Not Exist”


Test splitting is a feature provided by CircleCI to optimize testing times. Splitting by historical timing data distributes tests most evenly across all parallel executors.

Although, circleci tests split --split-by=timings can output the following warning:

Error reading historical timing data: file does not exist


Why It Happens and How To Fix It

This can happen for several reasons including, but not limited to:

  1. The job parallelism is set to 1. Parallelism needs to be set to at least 2 to generate and attach historical timing data.
  2. The test splitting job has not had a successful test run that generated the appropriately formatted test results file.
  3. The test results files are not stored via store_test_results.


Additional Resources:

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