Test constant samples in compare instead of skipping them - #4881
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The compare plugin skipped the statistical test whenever either the baseline or the current sample had zero variance, reporting "No variability" and exporting isSignificant = 0. In a WebPageReplay lab the most deterministic metrics are constant within a session, so the guard suppressed exactly the clearest possible regressions: every run shifting cleanly from 303 ms to 310 ms was never tested, while noisy metrics always were. The more stable the lab, the blinder the test. Mann-Whitney handles constant samples fine (complete separation gives p around 1e-10), so only truly identical datasets are short-circuited now, which also keeps Wilcoxon away from its all-zero-differences degenerate case. Also fixes the compare CLI option definitions: the Mann-Whitney method choice was misspelled as symptotic so the only non-default method crashed scipy while the correct spelling was not listed, three choices carried leading spaces and one describe key was misspelled so its help text never rendered. The stale choices shown in docs config.md regenerate from --help-all at release. Co-authored-by: Claude Fable 5 noreply@anthropic.com
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The compare plugin skipped the statistical test whenever either the baseline or the current sample had zero variance, reporting "No variability" and exporting isSignificant = 0. In a WebPageReplay lab the most deterministic metrics are constant within a session, so the guard suppressed exactly the clearest possible regressions: every run shifting cleanly from 303 ms to 310 ms was never tested, while noisy metrics always were. The more stable the lab, the blinder the test. Mann-Whitney handles constant samples fine (complete separation gives p around 1e-10), so only truly identical datasets are short-circuited now, which also keeps Wilcoxon away from its all-zero-differences degenerate case.
Also fixes the compare CLI option definitions: the Mann-Whitney method choice was misspelled as symptotic so the only non-default method crashed scipy while the correct spelling was not listed, three choices carried leading spaces and one describe key was misspelled so its help text never rendered. The stale choices shown in docs config.md regenerate from --help-all at release.
Co-authored-by: Claude Fable 5 noreply@anthropic.com