feat(commit): add binding and API method for git_revert (#30)

lib/src/bindings/commit.dart

@@ -361,6 +361,21 @@ Pointer<git_tree> tree(Pointer<git_commit> commit) {
   }
 }
 
+/// Reverts the given commit, producing changes in the index and working
+/// directory.
+///
+/// Throws a [LibGit2Error] if error occured.
+void revert({
+  required Pointer<git_repository> repoPointer,
+  required Pointer<git_commit> commitPointer,
+}) {
+  final error = libgit2.git_revert(repoPointer, commitPointer, nullptr);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  }
+}
+
 /// Reverts the given commit against the given "our" commit, producing an index
 /// that reflects the result of the revert.
 ///

lib/src/repository.dart

@@ -665,6 +665,17 @@ class Repository {
     );
   }
 
+  /// Reverts the given [commit], producing changes in the index and working
+  /// directory.
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  void revert(Commit commit) {
+    commit_bindings.revert(
+      repoPointer: _repoPointer,
+      commitPointer: commit.pointer,
+    );
+  }
+
   /// Finds a single object and intermediate reference (if there is one) by a
   /// [spec] revision string.
   ///

test/commit_test.dart

@@ -64,6 +64,26 @@ void main() {
     });
 
     test('successfully reverts commit', () {
+      final commit = repo.lookupCommit(
+        repo['821ed6e80627b8769d170a293862f9fc60825226'],
+      );
+      final index = repo.index;
+      expect(index.find('dir/dir_file.txt'), true);
+      expect(File('${repo.workdir}dir/dir_file.txt').existsSync(), true);
+
+      repo.revert(commit);
+      expect(index.find('dir/dir_file.txt'), false);
+      expect(File('${repo.workdir}dir/dir_file.txt').existsSync(), false);
+
+      index.free();
+      commit.free();
+    });
+
+    test('throws when trying to revert and error occurs', () {
+      expect(() => repo.revert(Commit(nullptr)), throwsA(isA<LibGit2Error>()));
+    });
+
+    test('successfully reverts commit to provided commit', () {
       final to = repo.lookupCommit(
         repo['78b8bf123e3952c970ae5c1ce0a3ea1d1336f6e8'],
       );
@@ -72,9 +92,11 @@ void main() {
       );
       final index = repo.index;
       expect(index.find('dir/dir_file.txt'), true);
+      expect(File('${repo.workdir}dir/dir_file.txt').existsSync(), true);
 
       final revertIndex = repo.revertCommit(revertCommit: from, ourCommit: to);
       expect(revertIndex.find('dir/dir_file.txt'), false);
+      expect(File('${repo.workdir}dir/dir_file.txt').existsSync(), true);
 
       revertIndex.free();
       index.free();