commit f1031c0cfa4e4827c7b642dcc9fa851e9881f4b1
author Todd Wang <toddw@google.com> Fri Dec 18 22:04:29 2015 -0800
committer Todd Wang <toddw@google.com> Fri Dec 18 22:04:29 2015 -0800
tree 4d70f6f9b129352de0543ff0cc6d2abd47eb4ce8
parent 7656b4bb639fadfe680465529d915659fbd0f781

gosh: Make Cleanup pop to the top of the dir stack.

Here's how I've written one of my tests:

func TestFoo(t *testing.T) {
  sh := gosh.NewShell(gosh.Opts{Fatalf: t.Fatalf, Logf: t.Logf})
  defer sh.Cleanup
  tmpDir := sh.MakeTempDir()
  sh.Pushd(tmpDir)
  defer sh.Popd()
  sh.Cmd("binary", "fails").Run()
}

The problem with this pattern is that if "binary" exits with a
non-0 exit code, sh.Err will be non-nil after Run, but the
deferred sh.Popd will then panic.

It should be easy for me to fix; I can just remove the deferred
sh.Popd.  But the problem is that the cwd is tmpDir, which is
deleted by Cleanup.  Any subsequent test that calls sh.Pushd will
fail, since os.Getwd will fail.

My fix in this CL is pop to the top of the dir stack, so even if
the user forgets to call Popd(), Cleanup will put us back in the
directory where we started.  This seems reasonable.

Change-Id: I7592cc7baab270b041ceb5e5a75cdf46b0cbe940