Add a CommandRunner class for dispatching commands to args.

pkg/args/test/command_runner_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library command_runner_test;
+
+import 'package:unittest/unittest.dart';
+import 'package:args/args.dart';
+
+import 'utils.dart';
+
+const _DEFAULT_USAGE = """
+Usage: test [command] <arguments>
+
+Global options:
+-h, --help    Print this usage information.
+
+Available commands:
+  help   Display help information for test.
+
+Run "test help [command]" for more information about a command.""";
+
+void main() {
+  var runner;
+  setUp(() {
+    runner = new CommandRunner("test", "A test command runner.");
+  });
+
+  test(".usageTemplate has a sane default", () {
+    expect(runner.usageTemplate,
+        equals("test [command] <arguments>"));
+  });
+
+  group(".usage", () {
+    test("returns the usage string", () {
+      expect(runner.usage, equals("""
+A test command runner.
+
+$_DEFAULT_USAGE"""));
+    });
+
+    test("contains custom commands", () {
+      runner.addCommand(new FooCommand());
+
+      expect(runner.usage, equals("""
+A test command runner.
+
+Usage: test [command] <arguments>
+
+Global options:
+-h, --help    Print this usage information.
+
+Available commands:
+  foo    Set a value.
+  help   Display help information for test.
+
+Run "test help [command]" for more information about a command."""));
+    });
+
+    test("contains custom options", () {
+      runner.topLevelArgParser.addFlag("foo", help: "Do something.");
+
+      expect(runner.usage, equals("""
+A test command runner.
+
+Usage: test [command] <arguments>
+
+Global options:
+-h, --help        Print this usage information.
+    --[no-]foo    Do something.
+
+Available commands:
+  help   Display help information for test.
+
+Run "test help [command]" for more information about a command."""));
+    });
+
+    test("doesn't print hidden commands", () {
+      runner.addCommand(new HiddenCommand());
+
+      expect(runner.usage, equals("""
+A test command runner.
+
+$_DEFAULT_USAGE"""));
+    });
+
+    test("doesn't print aliases", () {
+      runner.addCommand(new AliasedCommand());
+
+      expect(runner.usage, equals("""
+A test command runner.
+
+Usage: test [command] <arguments>
+
+Global options:
+-h, --help    Print this usage information.
+
+Available commands:
+  aliased   Set a value.
+  help      Display help information for test.
+
+Run "test help [command]" for more information about a command."""));
+    });
+  });
+
+  test("usageError splits up the message and usage", () {
+    expect(() => runner.usageError("message"),
+        throwsUsageError("message", _DEFAULT_USAGE));
+  });
+
+  group("run()", () {
+    test("runs a command", () {
+      var command = new FooCommand();
+      runner.addCommand(command);
+
+      expect(runner.run(["foo"]).then((_) {
+        expect(command.hasRun, isTrue);
+      }), completes);
+    });
+
+    test("runs an asynchronous command", () {
+      var command = new AsyncCommand();
+      runner.addCommand(command);
+
+      expect(runner.run(["async"]).then((_) {
+        expect(command.hasRun, isTrue);
+      }), completes);
+    });
+
+    test("runs a hidden comand", () {
+      var command = new HiddenCommand();
+      runner.addCommand(command);
+
+      expect(runner.run(["hidden"]).then((_) {
+        expect(command.hasRun, isTrue);
+      }), completes);
+    });
+
+    test("runs an aliased comand", () {
+      var command = new AliasedCommand();
+      runner.addCommand(command);
+
+      expect(runner.run(["als"]).then((_) {
+        expect(command.hasRun, isTrue);
+      }), completes);
+    });
+
+    test("runs a subcommand", () {
+      var command = new AsyncCommand();
+      runner.addCommand(new FooCommand()..addSubcommand(command));
+
+      expect(runner.run(["foo", "async"]).then((_) {
+        expect(command.hasRun, isTrue);
+      }), completes);
+    });
+
+    group("with --help", () {
+      test("with no command prints the usage", () {
+        expect(() => runner.run(["--help"]), prints("""
+A test command runner.
+
+$_DEFAULT_USAGE
+"""));
+      });
+
+      test("with a command prints the usage for that command", () {
+        var command = new FooCommand();
+        runner.addCommand(command);
+
+        expect(() => runner.run(["foo", "--help"]), prints("""
+Set a value.
+
+Usage: test foo
+-h, --help    Print this usage information.
+
+Run "test help" to see global options.
+"""));
+      });
+    });
+  });
+
+  group("throws a useful error when", () {
+    test("arg parsing fails", () {
+      expect(runner.run(["--bad"]),
+          throwsUsageError('Could not find an option named "bad".',
+              _DEFAULT_USAGE));
+    });
+
+    test("a top-level command doesn't exist", () {
+      expect(runner.run(["bad"]),
+          throwsUsageError('Could not find a command named "bad".',
+              _DEFAULT_USAGE));
+    });
+
+    test("a subcommand doesn't exist", () {
+      runner.addCommand(
+          new FooCommand()..addSubcommand(new AsyncCommand()));
+
+      expect(runner.run(["foo bad"]),
+          throwsUsageError('Could not find a command named "foo bad".', """
+Usage: test [command] <arguments>
+
+Global options:
+-h, --help    Print this usage information.
+
+Available commands:
+  foo    Set a value.
+  help   Display help information for test.
+
+Run "test help [command]" for more information about a command."""));
+    });
+
+    test("a subcommand wasn't passed", () {
+      runner.addCommand(
+          new FooCommand()..addSubcommand(new AsyncCommand()));
+
+      expect(runner.run(["foo"]),
+          throwsUsageError('Missing subcommand for "test foo".', """
+Usage: test foo
+-h, --help    Print this usage information.
+
+Available subcommands:
+  async   Set a value asynchronously.
+
+Run "test help" to see global options."""));
+    });
+
+    test("a command that doesn't take arguments was given them", () {
+      runner.addCommand(new FooCommand());
+
+      expect(runner.run(["foo", "bar"]),
+          throwsUsageError('Command "foo" does not take any arguments.', """
+Usage: test foo
+-h, --help    Print this usage information.
+
+Run "test help" to see global options."""));
+    });
+  });
+}