1 files changed, 57 insertions, 0 deletions
diff --git a/tests/unittests/conftest.py b/tests/unittests/conftest.py
new file mode 100644
index 00000000..e265a285
--- /dev/null
+++ b/tests/unittests/conftest.py
@@ -0,0 +1,57 @@
+import builtins
+import glob
+import os
+
+import pytest
+
+from cloudinit import atomic_helper, util
+from tests.unittests.helpers import retarget_many_wrapper
+
+FS_FUNCS = {
+    os.path: [
+        ("isfile", 1),
+        ("exists", 1),
+        ("islink", 1),
+        ("isdir", 1),
+        ("lexists", 1),
+        ("relpath", 1),
+    ],
+    os: [
+        ("listdir", 1),
+        ("mkdir", 1),
+        ("lstat", 1),
+        ("symlink", 2),
+        ("stat", 1),
+        ("scandir", 1),
+    ],
+    util: [
+        ("write_file", 1),
+        ("append_file", 1),
+        ("load_file", 1),
+        ("ensure_dir", 1),
+        ("chmod", 1),
+        ("delete_dir_contents", 1),
+        ("del_file", 1),
+        ("sym_link", -1),
+        ("copy", -1),
+    ],
+    glob: [
+        ("glob", 1),
+    ],
+    builtins: [
+        ("open", 1),
+    ],
+    atomic_helper: [
+        ("write_file", 1),
+    ],
+}
+
+
+@pytest.fixture
+def fake_filesystem(mocker, tmpdir):
+    """Mocks fs functions to operate under `tmpdir`"""
+    for (mod, funcs) in FS_FUNCS.items():
+        for f, nargs in funcs:
+            func = getattr(mod, f)
+            trap_func = retarget_many_wrapper(str(tmpdir), nargs, func)
+            mocker.patch.object(mod, f, trap_func)