feat(commit): add base bindings and api

test/commit_test.dart

@@ -0,0 +1,79 @@
+import 'dart:io';
+
+import 'package:test/test.dart';
+import 'package:libgit2dart/libgit2dart.dart';
+import 'package:libgit2dart/src/commit.dart';
+import 'helpers/util.dart';
+
+void main() {
+  const mergeCommit = '78b8bf123e3952c970ae5c1ce0a3ea1d1336f6e8';
+
+  group('Commit', () {
+    late Repository repo;
+    final tmpDir = '${Directory.systemTemp.path}/ref_testrepo/';
+
+    setUp(() async {
+      if (await Directory(tmpDir).exists()) {
+        await Directory(tmpDir).delete(recursive: true);
+      }
+      await copyRepo(
+        from: Directory('test/assets/testrepo/'),
+        to: await Directory(tmpDir).create(),
+      );
+      repo = Repository.open(tmpDir);
+    });
+
+    tearDown(() async {
+      repo.free();
+      await Directory(tmpDir).delete(recursive: true);
+    });
+
+    group('lookup', () {
+      test('successful when 40 char sha hex is provided', () {
+        final commit = repo[mergeCommit];
+        expect(commit, isA<Commit>());
+        commit.free();
+      });
+
+      test('successful when sha hex is short', () {
+        final commit = repo[mergeCommit.substring(0, 5)];
+        expect(commit, isA<Commit>());
+        commit.free();
+      });
+
+      test('throws when provided sha hex is invalid', () {
+        expect(() => repo['invalid'], throwsA(isA<ArgumentError>()));
+      });
+
+      test('throws when nothing found', () {
+        expect(() => repo['970ae5c'], throwsA(isA<LibGit2Error>()));
+      });
+
+      test('returns with correct fields', () {
+        final signature = Signature.create(
+          name: 'Aleksey Kulikov',
+          email: 'skinny.mind@gmail.com',
+          time: 1626091184,
+          offset: 180,
+        );
+        final commit = repo[mergeCommit];
+
+        expect(commit.messageEncoding, 'utf-8');
+        expect(commit.message, 'Merge branch \'feature\'\n');
+        expect(commit.id.sha, mergeCommit);
+        expect(commit.parents.length, 2);
+        expect(
+          commit.parents[0].id.sha,
+          'c68ff54aabf660fcdd9a2838d401583fe31249e3',
+        );
+        expect(commit.time, 1626091184);
+        expect(commit.committer, signature);
+        expect(commit.author, signature);
+        expect(commit.tree.sha, '7796359a96eb722939c24bafdb1afe9f07f2f628');
+
+        signature.free();
+        commit.free();
+      });
+    });
+  });
+}