Let vigil run without sudo.

Now using user namespaces which allow unprivileged users to create
the sandbox.

sandbox_fs_test.py

@@ -4,40 +4,39 @@
 # Licensed under the Artistic License 2.0.
 
 import os
+import sys
 import subprocess
 import tempfile
 import unittest
 
-import sandbox_fs
+
+tempfile.tempdir = os.getcwd()  # This tests fails when using /tmp.
+
+
+def _get_test_paths(temp_dir):
+    a_dir = os.path.join(temp_dir, "a")
+    foo_path = os.path.join(a_dir, "foo")
+    bar_path = os.path.join(temp_dir, "bar")
+    return a_dir, foo_path, bar_path
 
 
 class SandboxFilesystemTestCase(unittest.TestCase):
 
-    def setUp(self):
-        self.temp_dir = tempfile.mkdtemp()
-        self.sandbox = sandbox_fs.SandboxFs(self.temp_dir)
-        self.sandbox.mount()
-
-    def tearDown(self):
-        self.sandbox.umount()
-        os.rmdir(self.temp_dir)
-
-    def test_sandbox_minimal(self):
-        foo_upper_path = os.path.join(self.sandbox.mount_point, "foo")
-        subprocess.check_call(["sudo", "touch", foo_upper_path])
-        self.assertTrue(os.path.exists(foo_upper_path))
-        foo_lower_path = os.path.join(self.sandbox.overlay_mounts[0].lower_dir,
-                                      "foo")
-        self.assertFalse(os.path.exists(foo_lower_path))
-
-    def test_home_directory_exists_in_the_sandbox(self):
-        home_directory = (self.sandbox.mount_point + os.environ["HOME"])
-        self.assertTrue(os.path.exists(home_directory))
-
-    def test_run_a_command_in_the_sandbox(self):
-        stdout = subprocess.check_output(self.sandbox.command(["pwd"]))
-        self.assertEqual(stdout.strip().decode("utf-8"), os.environ["PWD"])
+    def test_sandbox(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            a_dir, foo_path, bar_path = _get_test_paths(temp_dir)
+            os.mkdir(a_dir)
+            subprocess.check_call(["./sandbox_fs", a_dir, "--", __file__,
+                                   temp_dir])
+            self.assertTrue(os.path.exists(foo_path))
+            self.assertFalse(os.path.exists(bar_path))
 
 
 if __name__ == "__main__":
-    unittest.main()
+    if len(sys.argv) > 1:
+        temp_dir = sys.argv[1]
+        a_dir, foo_path, bar_path = _get_test_paths(temp_dir)
+        subprocess.check_call(["touch", foo_path])
+        subprocess.check_call(["touch", bar_path])
+    else:
+        unittest.main()