--- /dev/null
+#!/usr/bin/env sh
+
+#
+# Git bisect is a helpful way to discover which commit an error
+# occurred in. This example file gives simple instructions for
+# using git bisect with Drush to quickly find erroneous commits
+# in Drush commands or Drupal modules, presuming that you can
+# trigger the error condition via Drush (e.g. using `drush php-eval`).
+#
+# Follow these simple steps:
+#
+# $ git bisect start
+# $ git bisect bad # Tell git that the current commit does not work
+# $ git bisect good bcadd5a # Tell drush that the commithash 12345 worked fine
+# $ git bisect run mytestscript.sh
+#
+# 'git bisect run' will continue to call 'git bisect good' and 'git bisect bad',
+# based on whether the script's exit code was 0 or 1, respectively.
+#
+# Replace 'mytestscript.sh' in the example above with a custom script that you
+# write yourself. Use the example script at the end of this document as a
+# guide. Replace the example command with one that calls the Drush command
+# that you would like to test, and replace the 'grep' string with a value
+# that appears when the error exists in the commit, but does not appear when
+# commit is okay.
+#
+# If you are using Drush to test Drupal or an external Drush module, use:
+#
+# $ git bisect run drush mycommand --strict=2
+#
+# This presumes that there is one or more '[warning]' or '[error]'
+# messages emitted when there is a problem, and no warnings or errors
+# when the commit is okay. Omit '--strict=2' to ignore warnings, and
+# signal failure only when 'error' messages are emitted.
+#
+# If you need to test for an error condition explicitly, to find errors
+# that do not return any warning or error log messages on their own, you
+# can use the Drush php-eval command to force an error when `myfunction()`
+# returns FALSE. Replace 'myfunction()' with the name of an appropriate
+# function in your module that can be used to detect the error condition
+# you are looking for.
+#
+# $ git bisect run drush ev 'if(!myfunction()) { return drush_set_error("ERR"); }'
+#
+drush mycommand --myoption 2>&1 | grep -q 'string that indicates there was a problem'
+if [ $? == 0 ] ; then
+ exit 1
+else
+ exit 0
+fi