old_contents: from os.path import isdir
  
  import pytest
  from filesystem_tree import FilesystemTree
  
  
  @pytest.yield_fixture
  def fs():
      fs = FilesystemTree()
      yield fs
      fs.remove()
  
  
  def test_it_can_be_instantiated():
      assert FilesystemTree().__class__.__name__ == 'FilesystemTree'
  
  def test_args_go_to_mk_not_root():
      fs = FilesystemTree('foo', 'bar')
      assert fs.root != 'foo'
  
  def test_it_makes_a_directory(fs):
      assert isdir(fs.root)
  
  def test_remove_removes(fs):
      assert isdir(fs.root)
      fs.remove()
      assert not isdir(fs.root)
  
new_contents: import os
  from os.path import isdir
  
  import pytest
  from filesystem_tree import FilesystemTree
  
  
  @pytest.yield_fixture
  def fs():
      fs = FilesystemTree()
      yield fs
      fs.remove()
  
  
  def test_it_can_be_instantiated():
      assert FilesystemTree().__class__.__name__ == 'FilesystemTree'
  
  def test_args_go_to_mk_not_root():
      fs = FilesystemTree('foo', 'bar')
      assert fs.root != 'foo'
  
  def test_it_makes_a_directory(fs):
      assert isdir(fs.root)
  
  def test_resolve_resolves(fs):
      path = fs.resolve('some/dir')
      assert path == os.path.realpath(os.sep.join([fs.root, 'some', 'dir']))
  
  def test_mk_makes_a_dir(fs):
      fs.mk('some/dir')
      assert isdir(fs.resolve('some/dir'))
  
  def test_remove_removes(fs):
      assert isdir(fs.root)
      fs.remove()
      assert not isdir(fs.root)
  
subject: Add an initial test each for resolve and mk