Merge branch 'jk/sanity' into maint

The tests that wanted to see that file becomes unreadable after
running "chmod a-r file", and the tests that wanted to make sure it
is not run as root, we used "can we write into the / directory?" as
a cheap substitute, but on some platforms that is not a good
heuristics.  The tests and their prerequisites have been updated to
check what they really require.

* jk/sanity:
  test-lib.sh: set prerequisite SANITY by testing what we really need
  tests: correct misuses of POSIXPERM
  t/lib-httpd: switch SANITY check for NOT_ROOT

1 files changed, 13 insertions, 4 deletions

diff --git a/t/t1509-root-worktree.sh b/t/t1509-root-worktree.sh
index 335420fd87..b6977d4b39 100755
--- a/t/t1509-root-worktree.sh
+++ b/t/t1509-root-worktree.sh
@@ -98,8 +98,16 @@ test_foobar_foobar() {
 	'
 }
 
-if ! test_have_prereq POSIXPERM || ! [ -w / ]; then
-	skip_all="Dangerous test skipped. Read this test if you want to execute it"
+if ! test -w /
+then
+	skip_all="Test requiring writable / skipped. Read this test if you want to run it"
+	test_done
+fi
+
+if  test -e /refs || test -e /objects || test -e /info || test -e /hooks ||
+    test -e /.git || test -e /foo || test -e /me
+then
+	skip_all="Skip test that clobbers existing files in /"
 	test_done
 fi
 
@@ -108,8 +116,9 @@ if [ "$IKNOWWHATIAMDOING" != "YES" ]; then
 	test_done
 fi
 
-if [ "$UID" = 0 ]; then
-	skip_all="No you can't run this with root"
+if ! test_have_prereq NOT_ROOT
+then
+	skip_all="No you can't run this as root"
 	test_done
 fi