feat(shorebird_cli): create Git wrapper

packages/shorebird_cli/lib/src/git.dart

@@ -0,0 +1,36 @@
+import 'dart:io';
+
+import 'package:shorebird_cli/src/process.dart';
+
+/// A wrapper around all git related functionality.
+class Git {
+  static const executable = 'git';
+
+  /// Clones the git repository located at [url] into the [outputDirectory].
+  /// `git clone <url> ...<args> <outputDirectory>`
+  Future<void> clone({
+    required String url,
+    required String outputDirectory,
+    List<String>? args,
+  }) async {
+    final arguments = [
+      'clone',
+      url,
+      ...?args,
+      outputDirectory,
+    ];
+    final result = await process.run(
+      executable,
+      arguments,
+      runInShell: true,
+    );
+    if (result.exitCode != 0) {
+      throw ProcessException(
+        executable,
+        arguments,
+        '${result.stderr}',
+        result.exitCode,
+      );
+    }
+  }
+}

packages/shorebird_cli/test/src/git_test.dart

@@ -0,0 +1,97 @@
+import 'dart:io';
+
+import 'package:mason_logger/mason_logger.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:scoped/scoped.dart';
+import 'package:shorebird_cli/src/git.dart';
+import 'package:shorebird_cli/src/process.dart';
+import 'package:test/test.dart';
+
+class _MockShorebirdProcess extends Mock implements ShorebirdProcess {}
+
+class _MockShorebirdProcessResult extends Mock
+    implements ShorebirdProcessResult {}
+
+void main() {
+  group(Git, () {
+    late ShorebirdProcessResult processResult;
+    late ShorebirdProcess process;
+    late Git git;
+
+    R runWithOverrides<R>(R Function() body) {
+      return runScoped(
+        () => body(),
+        values: {
+          processRef.overrideWith(() => process),
+        },
+      );
+    }
+
+    setUp(() {
+      processResult = _MockShorebirdProcessResult();
+      process = _MockShorebirdProcess();
+      git = runWithOverrides(Git.new);
+
+      when(
+        () => process.run(any(), any(), runInShell: any(named: 'runInShell')),
+      ).thenAnswer((_) async => processResult);
+      when(() => processResult.exitCode).thenReturn(ExitCode.success.code);
+    });
+
+    group('clone', () {
+      const url = 'https://github.com/shorebirdtech/shorebird';
+      const outputDirectory = './output';
+
+      test('executes correct command (no args)', () async {
+        await runWithOverrides(
+          () => git.clone(
+            url: url,
+            outputDirectory: outputDirectory,
+          ),
+        );
+        verify(
+          () => process.run(
+            'git',
+            ['clone', url, outputDirectory],
+            runInShell: true,
+          ),
+        ).called(1);
+      });
+
+      test('executes correct command (with args)', () async {
+        const args = <String>['--filter-tree:0', '--no-checkout'];
+        await runWithOverrides(
+          () => git.clone(
+            url: url,
+            args: ['--filter-tree:0', '--no-checkout'],
+            outputDirectory: outputDirectory,
+          ),
+        );
+        verify(
+          () => process.run(
+            'git',
+            ['clone', url, ...args, outputDirectory],
+            runInShell: true,
+          ),
+        ).called(1);
+      });
+
+      test('throws ProcessException if process exits with error', () async {
+        const error = 'oops';
+        when(() => processResult.exitCode).thenReturn(ExitCode.software.code);
+        when(() => processResult.stderr).thenReturn(error);
+        expect(
+          () => runWithOverrides(
+            () => git.clone(
+              url: url,
+              outputDirectory: outputDirectory,
+            ),
+          ),
+          throwsA(
+            isA<ProcessException>().having((e) => e.message, 'message', error),
+          ),
+        );
+      });
+    });
+  });
+}