add regression test utility

test_regression.sh

@@ -0,0 +1,86 @@
+#!/usr/bin/env bash
+
+# ## Usage examples:
+#
+# Test current branch against master:
+#    test_regression.sh
+# Test current branch against another branch:
+#    test_regression.sh another-branch
+# Test current branch against master passing arguments to busted:
+#    test_regression.sh -- --exclude-tags=flaky
+# Test current branch against next passing arguments to busted:
+#    test_regression.sh next -- --exclude-tags=flaky
+
+if [ $(git status --untracked-files=no --porcelain | wc -l) != "0" ]
+then
+   echo "=============================="
+   echo "Local tree is not clean, please commit or stash before running this."
+   echo "=============================="
+   exit 1
+fi
+
+newbranch=$(git rev-parse --abbrev-ref HEAD)
+if [ "$newbranch" = "master" ] || [ "$newbranch" = "next" ]
+then
+   echo "=============================="
+   echo "Please run this from a topic branch, and not from 'next' or 'master'."
+   echo "=============================="
+   exit 1
+fi
+
+basebranch="$1"
+if [ "$1" == "" ] || [ "$1" == "--" ]
+then
+   basebranch=master
+else
+   basebranch="$1"
+   shift
+fi
+if [ "$1" == "--" ]
+then
+   shift
+fi
+
+git checkout "$newbranch"
+rm -rf .spec-new
+rm -rf .spec-old
+cp -a spec .spec-new
+git checkout "$basebranch"
+
+echo "----------------------------------------"
+echo "Tests changed between $basebranch and $newbranch:"
+echo "----------------------------------------"
+specfiles=($(git diff-tree --no-commit-id --name-only -r "..$newbranch" | grep "^spec/"))
+echo "${specfiles[@]}"
+echo "----------------------------------------"
+
+mv spec .spec-old
+mv .spec-new spec
+./luarocks test -- "${specfiles[@]}" "$@"
+if [ $? = 0 ]
+then
+   git checkout .
+   git checkout $newbranch
+   echo "=============================="
+   echo "Regression test does not trigger the issue in base branch"
+   echo "=============================="
+   exit 1
+fi
+mv spec .spec-new
+mv .spec-old spec
+git checkout $newbranch
+./luarocks test -- "${specfiles[@]}" "$@"
+ret=$?
+if [ "$ret" != "0" ]
+then
+   echo "=============================="
+   echo "New branch does not fix issue (returned $ret)"
+   echo "=============================="
+   exit 1
+fi
+
+echo "=============================="
+echo "All good! New branch fixes regression!"
+echo "=============================="
+exit 0
+