def test_cgroupsSuggestsDocker(self):
        """
        If the platform is Linux, and the cgroups file (faked out here) exists,
        and one of the paths starts with C{/docker/}, C{isDocker()} returns
        C{True}.
        """
        cgroupsFile = self.mktemp()
        with open(cgroupsFile, 'wb') as f:
            # real cgroups file from inside a Debian 7 docker container
            f.write(b"""10:debug:/
9:net_prio:/
8:perf_event:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
7:net_cls:/
6:freezer:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
5:devices:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
4:blkio:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
3:cpuacct:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
2:cpu:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f
1:cpuset:/docker/104155a6453cb67590027e397dc90fc25a06a7508403c797bc89ea43adf8d35f""")

        platform = Platform(None, 'linux')
        self.assertTrue(platform.isDocker(_initCGroupLocation=cgroupsFile))

        If the platform is Linux, and the cgroups file (faked out here) exists,
        and one of the paths starts with C{/docker/}, C{isDocker()} returns
        C{True}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_runtime.py