Add Repository.revert()

This exposes libgit2's git_revert(), which produces changes in the index and working directory. It also affects the repository's state (via .git/REVERT_HEAD) and prepared message (via .git/MERGE_MSG).

The existing function Repository.revert_commit(), which exposes git_revert_commit(), is less powerful -- it doesn't check out the resulting index, and it doesn't modify the state and prepared message.

Note: git_revert() takes additional checkout/revert settings. We could implement support for these as extra arguments to Repository.revert() in the future.

Author: jorio

pygit2/decl/revert.h

@@ -1,3 +1,17 @@
+#define GIT_REVERT_OPTIONS_VERSION ...
+
+typedef struct {
+	unsigned int version;
+	unsigned int mainline;
+	git_merge_options merge_opts;
+	git_checkout_options checkout_opts;
+} git_revert_options;
+
+int git_revert(
+	git_repository *repo,
+	git_commit *commit,
+	const git_revert_options *given_opts);
+
 int git_revert_commit(
 	git_index **out,
 	git_repository *repo,

pygit2/repository.py

@@ -1343,6 +1343,19 @@ def set_ident(self, name, email):
         err = C.git_repository_set_ident(self._repo, to_bytes(name), to_bytes(email))
         check_error(err)
 
+    def revert(self, commit: Commit):
+        """
+        Revert the given commit, producing changes in the index and working
+        directory.
+
+        This operation updates the repository's state and prepared message
+        (MERGE_MSG).
+        """
+        commit_ptr = ffi.new('git_commit **')
+        ffi.buffer(commit_ptr)[:] = commit._pointer[:]
+        err = C.git_revert(self._repo, commit_ptr[0], ffi.NULL)
+        check_error(err)
+
     def revert_commit(self, revert_commit, our_commit, mainline=0):
         """
         Revert the given Commit against the given "our" Commit, producing an

test/test_repository.py

@@ -39,6 +39,7 @@
     FileStatus,
     ObjectType,
     RepositoryOpenFlag,
+    RepositoryState,
     ResetMode,
     StashApplyProgress,
 )
@@ -538,7 +539,7 @@ def checkout_notify(self, why, path, baseline, target, workdir):
         assert f.read() == 'stashed content'
 
 
-def test_revert(testrepo):
+def test_revert_commit(testrepo):
     master = testrepo.head.peel()
     commit_to_revert = testrepo['4ec4389a8068641da2d6578db0419484972284c8']
     parent = commit_to_revert.parents[0]
@@ -552,6 +553,26 @@ def test_revert(testrepo):
     assert revert_diff_stats.files_changed == commit_diff_stats.files_changed
 
 
+def test_revert(testrepo):
+    hello_txt = Path(testrepo.workdir) / 'hello.txt'
+    commit_to_revert = testrepo['4ec4389a8068641da2d6578db0419484972284c8']
+
+    assert testrepo.state() == RepositoryState.NONE
+    assert not testrepo.message
+    assert 'bonjour le monde' in hello_txt.read_text()
+
+    # Revert addition of French line in hello.txt
+    testrepo.revert(commit_to_revert)
+
+    assert 'bonjour le monde' not in hello_txt.read_text()
+    assert testrepo.status()['hello.txt'] == FileStatus.INDEX_MODIFIED
+    assert testrepo.state() == RepositoryState.REVERT
+    assert (
+        testrepo.message
+        == f'Revert "Say hello in French"\n\nThis reverts commit {commit_to_revert.id}.\n'
+    )
+
+
 def test_default_signature(testrepo):
     config = testrepo.config
     config['user.name'] = 'Random J Hacker'