Merge pull request #5658 from endolith/patch-1

charris · charris · commit 8e026a222599 · 2015-03-09T23:19:20.000-04:00
DOC: Add note about random seeds for unit testing
diff --git a/doc/TESTS.rst.txt b/doc/TESTS.rst.txt
@@ -374,3 +374,13 @@ at the end of the test run.  Skipped tests are marked as ``'S'`` in
 the test results (or ``'SKIPPED'`` for ``verbose > 1``), and known
 failing tests are marked as ``'K'`` (or ``'KNOWN'`` if ``verbose >
 1``).
+
+Tests on random data
+--------------------
+
+Tests on random data are good, but since test failures are meant to expose
+new bugs or regressions, a test that passes most of the time but fails
+occasionally with no code changes is not helpful. Make the random data
+deterministic by setting the random number seed before generating it.  Use
+either Python's ``random.seed(some_number)`` or Numpy's
+``numpy.random.seed(some_number)``, depending on the source of random numbers.
