git: do not let git clones clobber the target directory (by default)

CHANGES.md

@@ -4,7 +4,9 @@
 2.3b5 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Do not clobber git clones by default. Add new option `clobber` to allow
+  specifying that a git clone may clobber the target directory.
+  ([#298](https://github.com/flyingcircusio/batou/issues/298))
 
 
 2.3b4 (2022-08-22)

src/batou/lib/git.py

@@ -28,6 +28,7 @@ class Clone(Component):
     revision = None
     branch = None
     vcs_update = True
+    clobber = False
 
     def configure(self):
         if (not self.revision_or_branch) or (self.revision and self.branch):
@@ -64,13 +65,25 @@ def verify(self):
                 )
 
             if self.has_changes():
-                output.annotate(
-                    "Git clone at {} is dirty, going to lose changes.".format(
-                        self.target
-                    ),
-                    red=True,
-                )
-                raise UpdateNeeded()
+                if self.clobber:
+                    output.annotate(
+                        "Git clone at {} is dirty, going to lose changes.".format(
+                            self.target
+                        ),
+                        red=True,
+                    )
+                    raise UpdateNeeded()
+                else:
+                    output.annotate(
+                        "Git clone at {} is dirty - refusing to clobber. "
+                        "Use `clobber=True` if this is intentional .".format(
+                            self.target
+                        ),
+                        red=True,
+                    )
+                    raise RuntimeError(
+                        "Refusing to clobber dirty work directory."
+                    )
 
             if self.revision and self.current_revision() != self.revision:
                 raise UpdateNeeded()

src/batou/lib/tests/test_git.py

@@ -159,7 +159,7 @@ def test_clean_clone_updates_on_incoming_changes(root, repos_path):
 
 
 @pytest.mark.slow
-def test_changes_lost_on_update_with_incoming(root, repos_path):
+def test_no_clobber_changes_protected_on_update_with_incoming(root, repos_path):
     root.component += batou.lib.git.Clone(
         repos_path, target="clone", branch="master"
     )
@@ -170,16 +170,69 @@ def test_changes_lost_on_update_with_incoming(root, repos_path):
         )
     )
     cmd("cd {dir}/clone; echo foobar >foo".format(dir=root.workdir))
+    with pytest.raises(RuntimeError) as e:
+        root.component.deploy()
+    assert e.value.args[0] == "Refusing to clobber dirty work directory."
+    with open(root.component.map("clone/foo")) as f:
+        assert f.read() == "foobar\n"
+
+
+@pytest.mark.slow
+def test_no_clobber_changes_protected_on_update_without_incoming(
+    root, repos_path
+):
+    root.component += batou.lib.git.Clone(
+        repos_path, target="clone", branch="master"
+    )
+    root.component.deploy()
+    cmd("cd {dir}/clone; echo foobar >foo".format(dir=root.workdir))
+    with pytest.raises(RuntimeError) as e:
+        root.component.deploy()
+    assert e.value.args[0] == "Refusing to clobber dirty work directory."
+    with open(root.component.map("clone/foo")) as f:
+        assert f.read() == "foobar\n"
+
+
+@pytest.mark.slow
+def test_no_clobber_untracked_files_are_kept_on_update(root, repos_path):
+    root.component += batou.lib.git.Clone(
+        repos_path, target="clone", branch="master"
+    )
+    root.component.deploy()
+    cmd(
+        "cd {dir}/clone; mkdir bar; echo foobar >bar/baz".format(
+            dir=root.workdir
+        )
+    )
+    with pytest.raises(RuntimeError) as e:
+        root.component.deploy()
+    assert e.value.args[0] == "Refusing to clobber dirty work directory."
+    with open(root.component.map("clone/bar/baz")) as f:
+        assert f.read() == "foobar\n"
+
+
+@pytest.mark.slow
+def test_clobber_changes_lost_on_update_with_incoming(root, repos_path):
+    root.component += batou.lib.git.Clone(
+        repos_path, target="clone", branch="master", clobber=True
+    )
+    root.component.deploy()
+    cmd(
+        'cd {dir}; touch bar; git add .; git commit -m "commit"'.format(
+            dir=repos_path
+        )
+    )
+    cmd("cd {dir}/clone; echo foobar >foo".format(dir=root.workdir))
     root.component.deploy()
     assert os.path.exists(root.component.map("clone/bar"))
     with open(root.component.map("clone/foo")) as f:
         assert not f.read()
 
 
 @pytest.mark.slow
-def test_changes_lost_on_update_without_incoming(root, repos_path):
+def test_clobber_changes_lost_on_update_without_incoming(root, repos_path):
     root.component += batou.lib.git.Clone(
-        repos_path, target="clone", branch="master"
+        repos_path, target="clone", branch="master", clobber=True
     )
     root.component.deploy()
     cmd("cd {dir}/clone; echo foobar >foo".format(dir=root.workdir))
@@ -189,9 +242,9 @@ def test_changes_lost_on_update_without_incoming(root, repos_path):
 
 
 @pytest.mark.slow
-def test_untracked_files_are_removed_on_update(root, repos_path):
+def test_clobber_untracked_files_are_removed_on_update(root, repos_path):
     root.component += batou.lib.git.Clone(
-        repos_path, target="clone", branch="master"
+        repos_path, target="clone", branch="master", clobber=True
     )
     root.component.deploy()
     cmd(