feat(branch): add more bindings and api methods

test/branch_test.dart

@@ -26,7 +26,7 @@ void main() {
 
   group('Branch', () {
     test('returns a list of all branches', () {
-      const branchesExpected = ['feature', 'master'];
+      const branchesExpected = ['feature', 'master', 'origin/master'];
       final branches = repo.branches;
 
       for (var i = 0; i < branches.length; i++) {
@@ -46,7 +46,13 @@ void main() {
     });
 
     test('returns a list of remote branches', () {
-      expect(repo.branchesRemote, <Branch>[]);
+      const branchesExpected = ['origin/master'];
+      final branches = repo.branchesRemote;
+
+      for (var i = 0; i < branches.length; i++) {
+        expect(branches[i].name, branchesExpected[i]);
+        branches[i].free();
+      }
     });
 
     test('throws when trying to return list and error occurs', () {
@@ -121,6 +127,113 @@ void main() {
       expect(() => nullBranch.name, throwsA(isA<LibGit2Error>()));
     });
 
+    test('returns remote name of a remote-tracking branch', () {
+      final branch = repo.branchesRemote.first;
+      expect(branch.remoteName, 'origin');
+      branch.free();
+    });
+
+    test(
+        'throws when getting remote name of a remote-tracking branch and '
+        'error occurs', () {
+      final branch = repo.lookupBranch(name: 'master');
+      expect(() => branch.remoteName, throwsA(isA<LibGit2Error>()));
+    });
+
+    test('returns upstream of a local branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      final upstream = branch.upstream;
+
+      expect(upstream.isRemote, true);
+      expect(upstream.name, 'refs/remotes/origin/master');
+
+      upstream.free();
+      branch.free();
+    });
+
+    test('throws when trying to get upstream of a remote branch', () {
+      final branch = repo.branchesRemote.first;
+      expect(() => branch.upstream, throwsA(isA<LibGit2Error>()));
+      branch.free();
+    });
+
+    test('successfully sets upstream of a branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      var upstream = branch.upstream;
+      expect(upstream.name, 'refs/remotes/origin/master');
+
+      final ref = repo.createReference(
+        name: 'refs/remotes/origin/new',
+        target: 'refs/heads/master',
+      );
+      branch.setUpstream(ref.shorthand);
+
+      upstream = branch.upstream;
+      expect(upstream.name, 'refs/remotes/origin/new');
+
+      ref.free();
+      upstream.free();
+      branch.free();
+    });
+
+    test('successfully unsets upstream of a branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      final upstream = branch.upstream;
+      expect(upstream.name, 'refs/remotes/origin/master');
+
+      branch.setUpstream(null);
+      expect(() => branch.upstream, throwsA(isA<LibGit2Error>()));
+
+      upstream.free();
+      branch.free();
+    });
+
+    test('throws when trying to set upstream of a branch and error occurs', () {
+      final branch = repo.lookupBranch(name: 'master');
+      expect(
+        () => branch.setUpstream('some/upstream'),
+        throwsA(isA<LibGit2Error>()),
+      );
+      branch.free();
+    });
+
+    test('returns upstream name of a local branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      expect(branch.upstreamName, 'refs/remotes/origin/master');
+      branch.free();
+    });
+
+    test('throws when trying to get upstream name of a branch and error occurs',
+        () {
+      final branch = repo.lookupBranch(name: 'feature');
+      expect(() => branch.upstreamName, throwsA(isA<LibGit2Error>()));
+      branch.free();
+    });
+
+    test('returns upstream remote of a local branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      expect(branch.upstreamRemote, 'origin');
+      branch.free();
+    });
+
+    test('throws when trying to get upstream remote of a remote branch', () {
+      final branch = repo.branchesRemote.first;
+      expect(() => branch.upstreamName, throwsA(isA<LibGit2Error>()));
+      branch.free();
+    });
+
+    test('returns upstream merge of a local branch', () {
+      final branch = repo.lookupBranch(name: 'master');
+      expect(branch.upstreamMerge, 'refs/heads/master');
+      branch.free();
+    });
+
+    test('throws when trying to get upstream merge of a remote branch', () {
+      final branch = repo.branchesRemote.first;
+      expect(() => branch.upstreamMerge, throwsA(isA<LibGit2Error>()));
+      branch.free();
+    });
+
     group('create()', () {
       test('successfully creates', () {
         final commit = repo.lookupCommit(lastCommit);
@@ -128,7 +241,7 @@ void main() {
         final branch = repo.createBranch(name: 'testing', target: commit);
         final branches = repo.branches;
 
-        expect(repo.branches.length, 3);
+        expect(repo.branches.length, 4);
         expect(branch.target, lastCommit);
 
         for (final branch in branches) {
@@ -194,7 +307,7 @@ void main() {
         final branch = repo.lookupBranch(name: 'renamed');
         final branches = repo.branches;
 
-        expect(branches.length, 2);
+        expect(branches.length, 3);
         expect(
           () => repo.lookupBranch(name: 'feature'),
           throwsA(isA<LibGit2Error>()),