Run each test in a clean directory

test/runner

@@ -12,15 +12,38 @@ try() {
 
 setUp() {
   export TMPDIR="$PWD/.generated"
+  export-repo-root
+  move-to-working-directory
 }
 
 tearDown() {
   [ "${_shunit_test_:=}" = '' ] && return 0
+
+  clean-up-working-directory
+
   if [ "${__shunit_testSuccess:?}" != 0 ]; then
     output-outputs
   fi
 }
 
+export-repo-root() {
+  export REPO_ROOT="$PWD"
+  while ! [[ -d $REPO_ROOT/.git ]]; do
+    export REPO_ROOT=$(dirname $REPO_ROOT)
+  done
+}
+
+move-to-working-directory() {
+  original_dir="$PWD"
+  working_dir=$(mktemp -d)
+  cd $working_dir
+}
+
+clean-up-working-directory() {
+  cd $original_dir
+  rm -rf $working_dir
+}
+
 output-outputs() {
   (
   bold '*******Test failed********'