feat(create): validate project name (#6)

Author: felangel

lib/src/command_runner.dart

@@ -19,7 +19,7 @@ class VeryGoodCommandRunner extends CommandRunner<int> {
       negatable: false,
       help: 'Print the current version.',
     );
-    addCommand(CreateCommand());
+    addCommand(CreateCommand(logger: logger));
   }
 
   final Logger _logger;

lib/src/commands/create.dart

@@ -2,12 +2,24 @@ import 'package:args/command_runner.dart';
 import 'package:io/io.dart';
 import 'package:mason/mason.dart';
 
+// A valid Dart identifier that can be used for a package, i.e. no
+// capital letters.
+// https://dart.dev/guides/language/language-tour#important-concepts
+final RegExp _identifierRegExp = RegExp('[a-z_][a-z0-9_]*');
+
 /// {@template create_command}
 /// `very_good create` command creates a new very good flutter app.
 /// {@endtemplate}
 class CreateCommand extends Command<int> {
   /// {@macro create_command}
-  CreateCommand({Logger logger}) : _logger = logger ?? Logger();
+  CreateCommand({Logger logger}) : _logger = logger ?? Logger() {
+    argParser.addOption(
+      'project-name',
+      help: 'The project name for this new Flutter project. '
+          'This must be a valid dart package name.',
+      defaultsTo: null,
+    );
+  }
 
   final Logger _logger;
 
@@ -20,7 +32,29 @@ class CreateCommand extends Command<int> {
 
   @override
   Future<int> run() async {
+    final projectName = argResults['project-name'];
+    if (projectName == null) {
+      throw UsageException(
+        'Required: --project-name.\n\n'
+        'e.g: very_good create --project-name my_app',
+        usage,
+      );
+    }
+    final isValidProjectName = _isValidPackageName(projectName);
+    if (!isValidProjectName) {
+      throw UsageException(
+        '"$projectName" is not a valid package name.\n\n'
+        'See https://dart.dev/tools/pub/pubspec#name for more information.',
+        usage,
+      );
+    }
     _logger.alert('Created a Very Good App! 🦄');
     return ExitCode.success.code;
   }
+
+  /// Whether [name] is a valid Dart package name.
+  bool _isValidPackageName(String name) {
+    final match = _identifierRegExp.matchAsPrefix(name);
+    return match != null && match.end == name.length;
+  }
 }

test/src/commands/create_test.dart

@@ -2,27 +2,48 @@ import 'package:io/io.dart';
 import 'package:mason/mason.dart';
 import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
+import 'package:very_good_cli/src/command_runner.dart';
 import 'package:very_good_cli/src/commands/create.dart';
 
 class MockLogger extends Mock implements Logger {}
 
 void main() {
   group('Create', () {
     Logger logger;
-    CreateCommand command;
+    VeryGoodCommandRunner commandRunner;
 
     setUp(() {
       logger = MockLogger();
-      command = CreateCommand(logger: logger);
+      commandRunner = VeryGoodCommandRunner(logger: logger);
     });
 
     test('can be instantiated without an explicit Logger instance', () {
       final command = CreateCommand();
       expect(command, isNotNull);
     });
 
+    test('throws UsageException when --project-name is missing', () async {
+      const expectedErrorMessage = 'Required: --project-name.\n\n'
+          'e.g: very_good create --project-name my_app';
+      final result = await commandRunner.run(['create']);
+      expect(result, equals(ExitCode.usage.code));
+      verify(logger.err(expectedErrorMessage)).called(1);
+    });
+
+    test('throws UsageException when --project-name is invalid', () async {
+      const expectedErrorMessage = '"My App" is not a valid package name.\n\n'
+          'See https://dart.dev/tools/pub/pubspec#name for more information.';
+      final result = await commandRunner.run(
+        ['create', '--project-name', 'My App'],
+      );
+      expect(result, equals(ExitCode.usage.code));
+      verify(logger.err(expectedErrorMessage)).called(1);
+    });
+
     test('completes successfully with correct output', () async {
-      final result = await command.run();
+      final result = await commandRunner.run(
+        ['create', '--project-name', 'my_app'],
+      );
       expect(result, equals(ExitCode.success.code));
       verify(logger.alert('Created a Very Good App! 🦄')).called(1);
     });