test: bump and log usage output test

test/functional_test.dart

@@ -7,6 +7,8 @@ import 'package:path/path.dart' as path;
 import 'package:pubspec_parse/pubspec_parse.dart';
 import 'package:test/test.dart';
 
+import 'subcommands_usage.expect.dart';
+
 void main() {
   late Directory temp;
   final out = BufferChannel();
@@ -232,12 +234,33 @@ I love my dog.
         expect(err.buffer.toString().trim(),
             'The next version must be higher than the current one.');
       });
-      test('version part must be specified', () async {
+      test('incorrect usage', () async {
         final code = await run(['bump']);
         expect(code, 64);
         expect(err.buffer.toString().trim().split('\n')[0],
             'Usage: cider bump <subcommand> [arguments]');
       });
+      test('help usage', () async {
+        final code = await run(['bump', '--help']);
+        expect(code, 0);
+        expect(err.buffer.toString(), isEmpty);
+        expectSubcommandsUsage(out.buffer.toString(), command: 'bump');
+      });
+    });
+  });
+
+  group('Log', () {
+    test('incorrect usage', () async {
+      final code = await run(['log']);
+      expect(code, 64);
+      expect(err.buffer.toString().trim().split('\n')[0],
+          'Usage: cider log <subcommand> [arguments]');
+    });
+    test('help usage', () async {
+      final code = await run(['log', '--help']);
+      expect(code, 0);
+      expect(err.buffer.toString(), isEmpty);
+      expectSubcommandsUsage(out.buffer.toString(), command: 'log');
     });
   });
 

test/subcommands_usage.expect.dart

@@ -0,0 +1,10 @@
+import 'package:test/test.dart';
+
+void expectSubcommandsUsage(String output, {String? command}) {
+  if (command != null) {
+    expect(output, contains('Usage: cider $command <subcommand> [arguments]'));
+  }
+  expect(output, contains('-h, --help    Print this usage information.'));
+  expect(output, contains('Available subcommands:'));
+  expect(output, contains('Run "cider help" to see global options.'));
+}