Skip tests that require root when not root

Also skip Chown on allocdir migration on Windows and when non-root.
Windows doesn't support it, and it will always fail as a non-root user.

client/alloc_watcher.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path/filepath"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/hashicorp/consul/lib"
@@ -517,9 +518,14 @@ func (p *remotePrevAlloc) streamAllocDir(ctx context.Context, resp io.ReadCloser
 				f.Close()
 				return fmt.Errorf("error chmoding file %v", err)
 			}
-			if err := f.Chown(hdr.Uid, hdr.Gid); err != nil {
-				f.Close()
-				return fmt.Errorf("error chowning file %v", err)
+
+			// Can't change owner if not root. Returns false on
+			// Windows as Chown always errors there.
+			if syscall.Geteuid() == 0 {
+				if err := f.Chown(hdr.Uid, hdr.Gid); err != nil {
+					f.Close()
+					return fmt.Errorf("error chowning file %v", err)
+				}
 			}
 
 			// We write in chunks so that we can test if the client

client/driver/lxc_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/hashicorp/nomad/client/config"
+	ctestutil "github.com/hashicorp/nomad/client/testutil"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/testutil"
 	lxc "gopkg.in/lxc/go-lxc.v2"
@@ -61,6 +62,7 @@ func TestLxcDriver_Start_Wait(t *testing.T) {
 	if !lxcPresent(t) {
 		t.Skip("lxc not present")
 	}
+	ctestutil.RequireRoot(t)
 
 	task := &structs.Task{
 		Name:   "foo",
@@ -137,6 +139,7 @@ func TestLxcDriver_Open_Wait(t *testing.T) {
 	if !lxcPresent(t) {
 		t.Skip("lxc not present")
 	}
+	ctestutil.RequireRoot(t)
 
 	task := &structs.Task{
 		Name:   "foo",

client/driver/qemu_test.go

@@ -127,6 +127,7 @@ func TestQemuDriver_GracefulShutdown(t *testing.T) {
 		t.Parallel()
 	}
 	ctestutils.QemuCompatible(t)
+	ctestutils.RequireRoot(t)
 	task := &structs.Task{
 		Name:   "linux",
 		Driver: "qemu",

client/testutil/driver_compatible.go

@@ -7,6 +7,13 @@ import (
 	"testing"
 )
 
+// RequireRoot skips tests unless running on a Unix as root.
+func RequireRoot(t *testing.T) {
+	if syscall.Geteuid() != 0 {
+		t.Skip("Must run as root on Unix")
+	}
+}
+
 func ExecCompatible(t *testing.T) {
 	if runtime.GOOS != "linux" || syscall.Geteuid() != 0 {
 		t.Skip("Test only available running as root on linux")