Extract atomic move function to utils.py

Moving atomically a file/directory can be tricky since different
errors might be raised for the same underlying problem.

Having a utility function to reduce this discrepancies will help
in ensuring we have correct behavior

2 files changed, 89 insertions, 62 deletions

diff --git a/tests/sources/git.py b/tests/sources/git.py
index e5bce44a8..7ab32a6b5 100644
--- a/tests/sources/git.py
+++ b/tests/sources/git.py
@@ -21,14 +21,11 @@
 #
 
 import os
-from unittest import mock
 import pytest
-import py.path
 
 from buildstream._exceptions import ErrorDomain
-from buildstream import _yaml, SourceError
+from buildstream import _yaml
 from buildstream.plugin import CoreWarnings
-from buildstream.plugins.sources.git import GitMirror
 
 from tests.testutils import cli, create_repo
 from tests.testutils.site import HAVE_GIT
@@ -39,64 +36,6 @@ DATA_DIR = os.path.join(
 )
 
 
-@pytest.mark.parametrize(
-    ["type_", "setup"],
-    [
-        ("inexistent-dir", lambda path: None),
-        ("empty-dir", lambda path: path.mkdir()),
-        ("non-empty-dir", lambda path: path.join("bad").write("hi", ensure=True)),
-        ("file", lambda path: path.write("no")),
-    ],
-)
-def test_git_mirror_atomic_move(tmpdir, type_, setup):
-    # Create required elements
-    class DummySource:
-        def get_mirror_directory(self):
-            return str(tmpdir.join("source").mkdir())
-
-        status = mock.MagicMock()
-
-    url = "file://{}/url".format(tmpdir)
-
-    # Create fake download directory
-    download_dir = tmpdir.join("download_dir")
-    download_dir.join("oracle").write("hello", ensure=True)
-
-    # Initiate mirror
-    mirror = GitMirror(DummySource(), None, url, None)
-
-    # Setup destination directory
-    setup(py.path.local(mirror.mirror))
-
-    # Copy directory content
-    if type_ == "file":
-        with pytest.raises(SourceError):
-            mirror._atomic_move_mirror(str(download_dir), mirror.url)
-    else:
-        mirror._atomic_move_mirror(str(download_dir), mirror.url)
-
-    # Validate
-    if type_ == "non-empty-dir":
-        # With a non empty directory, we should not have overriden
-        # and notified a status
-        assert DummySource.status.called
-
-        expected_oracle = os.path.join(mirror.mirror, "bad")
-        expected_content = "hi"
-    elif type_ == "file":
-        expected_oracle = mirror.mirror
-        expected_content = "no"
-    else:
-        # Otherwise we should have a new directory and the data
-        expected_oracle = os.path.join(mirror.mirror, "oracle")
-        expected_content = "hello"
-
-    assert os.path.exists(expected_oracle)
-
-    with open(expected_oracle) as fp:
-        assert fp.read() == expected_content
-
-
 @pytest.mark.skipif(HAVE_GIT is False, reason="git is not available")
 @pytest.mark.datafiles(os.path.join(DATA_DIR, 'template'))
 def test_fetch_bad_ref(cli, tmpdir, datafiles):
diff --git a/tests/utils/movedirectory.py b/tests/utils/movedirectory.py
new file mode 100755
index 000000000..6edbec611
--- /dev/null
+++ b/tests/utils/movedirectory.py
@@ -0,0 +1,88 @@
+import pytest
+
+from buildstream.utils import move_atomic, DirectoryExistsError
+
+
+@pytest.fixture
+def src(tmp_path):
+    src = tmp_path.joinpath("src")
+    src.mkdir()
+
+    with src.joinpath("test").open("w") as fp:
+        fp.write("test")
+
+    return src
+
+
+def test_move_to_empty_dir(src, tmp_path):
+    dst = tmp_path.joinpath("dst")
+
+    move_atomic(src, dst)
+
+    assert dst.joinpath("test").exists()
+
+
+def test_move_to_empty_dir_create_parents(src, tmp_path):
+    dst = tmp_path.joinpath("nested/dst")
+
+    move_atomic(src, dst)
+    assert dst.joinpath("test").exists()
+
+
+def test_move_to_empty_dir_no_create_parents(src, tmp_path):
+    dst = tmp_path.joinpath("nested/dst")
+
+    with pytest.raises(FileNotFoundError):
+        move_atomic(src, dst, ensure_parents=False)
+
+
+def test_move_non_existing_dir(tmp_path):
+    dst = tmp_path.joinpath("dst")
+    src = tmp_path.joinpath("src")
+
+    with pytest.raises(FileNotFoundError):
+        move_atomic(src, dst)
+
+
+def test_move_to_existing_empty_dir(src, tmp_path):
+    dst = tmp_path.joinpath("dst")
+    dst.mkdir()
+
+    move_atomic(src, dst)
+    assert dst.joinpath("test").exists()
+
+
+def test_move_to_existing_file(src, tmp_path):
+    dst = tmp_path.joinpath("dst")
+
+    with dst.open("w") as fp:
+        fp.write("error")
+
+    with pytest.raises(NotADirectoryError):
+        move_atomic(src, dst)
+
+
+def test_move_file_to_existing_file(tmp_path):
+    dst = tmp_path.joinpath("dst")
+    src = tmp_path.joinpath("src")
+
+    with src.open("w") as fp:
+        fp.write("src")
+
+    with dst.open("w") as fp:
+        fp.write("dst")
+
+    move_atomic(src, dst)
+    with dst.open() as fp:
+        assert fp.read() == "src"
+
+
+def test_move_to_existing_non_empty_dir(src, tmp_path):
+    dst = tmp_path.joinpath("dst")
+    dst.mkdir()
+
+    with dst.joinpath("existing").open("w") as fp:
+        fp.write("already there")
+
+    with pytest.raises(DirectoryExistsError):
+        move_atomic(src, dst)