move test code to another file

Lib/test/namespaces-test.py

@@ -0,0 +1,21 @@
+import os
+import sys
+
+
+def main():
+    fd = os.open('/proc/self/ns/uts', os.O_RDONLY)
+    try:
+        print(os.readlink('/proc/self/ns/uts'))
+        os.unshare(os.CLONE_NEWUTS)
+        print(os.readlink('/proc/self/ns/uts'))
+        os.setns(fd, os.CLONE_NEWUTS)
+        print(os.readlink('/proc/self/ns/uts'))
+    except OSError as e:
+        sys.stderr.write(str(e.errno))
+        sys.exit(2)
+    finally:
+        os.close(fd)
+
+
+if __name__ == '__main__':
+    main()

Lib/test/test_posix.py

@@ -2176,9 +2176,9 @@ class NamespacesTests(unittest.TestCase):
     """Tests for os.unshare() and os.setns()."""
 
     @support.requires_subprocess()
-    def subprocess(self, code):
+    def subprocess(self, file_path):
         import subprocess
-        with subprocess.Popen((sys.executable, '-c', code),
+        with subprocess.Popen((sys.executable, file_path),
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
             encoding="utf-8"
@@ -2195,22 +2195,7 @@ def subprocess(self, code):
     @unittest.skipUnless(os.path.exists('/proc/self/ns/uts'), 'need /proc/self/ns/uts')
     @support.requires_linux_version(3, 0, 0)
     def test_unshare_setns(self):
-        rc, out, err = self.subprocess("""if 1:
-            import os
-            import sys
-            fd = os.open('/proc/self/ns/uts', os.O_RDONLY)
-            try:
-                print(os.readlink('/proc/self/ns/uts'))
-                os.unshare(os.CLONE_NEWUTS)
-                print(os.readlink('/proc/self/ns/uts'))
-                os.setns(fd, os.CLONE_NEWUTS)
-                print(os.readlink('/proc/self/ns/uts'))
-            except OSError as e:
-                sys.stderr.write(str(e.errno))
-                sys.exit(2)
-            finally:
-                os.close(fd)
-            """)
+        rc, out, err = self.subprocess(support.findfile("namespaces-test.py"))
 
         if rc == 2:
             e = int(err[0])