diff --git a/tests/check_case_conflict_test.py b/tests/check_case_conflict_test.py
index 2a32918..b5f538a 100644
--- a/tests/check_case_conflict_test.py
+++ b/tests/check_case_conflict_test.py
@@ -4,63 +4,61 @@
 from pre_commit_hooks.check_case_conflict import find_conflicting_filenames
 from pre_commit_hooks.check_case_conflict import main
 from pre_commit_hooks.util import cmd_output
-from testing.util import cwd
-from testing.util import write_file
 
 
 def test_nothing_added(temp_git_dir):
-    with cwd(temp_git_dir):
+    with temp_git_dir.as_cwd():
         assert find_conflicting_filenames(['f.py']) == 0
 
 
 def test_adding_something(temp_git_dir):
-    with cwd(temp_git_dir):
-        write_file('f.py', "print('hello world')")
+    with temp_git_dir.as_cwd():
+        temp_git_dir.join('f.py').write("print('hello world')")
         cmd_output('git', 'add', 'f.py')
 
         assert find_conflicting_filenames(['f.py']) == 0
 
 
 def test_adding_something_with_conflict(temp_git_dir):
-    with cwd(temp_git_dir):
-        write_file('f.py', "print('hello world')")
+    with temp_git_dir.as_cwd():
+        temp_git_dir.join('f.py').write("print('hello world')")
         cmd_output('git', 'add', 'f.py')
-        write_file('F.py', "print('hello world')")
+        temp_git_dir.join('F.py').write("print('hello world')")
         cmd_output('git', 'add', 'F.py')
 
         assert find_conflicting_filenames(['f.py', 'F.py']) == 1
 
 
 def test_added_file_not_in_pre_commits_list(temp_git_dir):
-    with cwd(temp_git_dir):
-        write_file('f.py', "print('hello world')")
+    with temp_git_dir.as_cwd():
+        temp_git_dir.join('f.py').write("print('hello world')")
         cmd_output('git', 'add', 'f.py')
 
         assert find_conflicting_filenames(['g.py']) == 0
 
 
 def test_file_conflicts_with_committed_file(temp_git_dir):
-    with cwd(temp_git_dir):
-        write_file('f.py', "print('hello world')")
+    with temp_git_dir.as_cwd():
+        temp_git_dir.join('f.py').write("print('hello world')")
         cmd_output('git', 'add', 'f.py')
         cmd_output('git', 'commit', '--no-verify', '-m', 'Add f.py')
 
-        write_file('F.py', "print('hello world')")
+        temp_git_dir.join('F.py').write("print('hello world')")
         cmd_output('git', 'add', 'F.py')
 
         assert find_conflicting_filenames(['F.py']) == 1
 
 
 def test_integration(temp_git_dir):
-    with cwd(temp_git_dir):
+    with temp_git_dir.as_cwd():
         assert main(argv=[]) == 0
 
-        write_file('f.py', "print('hello world')")
+        temp_git_dir.join('f.py').write("print('hello world')")
         cmd_output('git', 'add', 'f.py')
 
         assert main(argv=['f.py']) == 0
 
-        write_file('F.py', "print('hello world')")
+        temp_git_dir.join('F.py').write("print('hello world')")
         cmd_output('git', 'add', 'F.py')
 
         assert main(argv=['F.py']) == 1