Add and use an abstraction over system and URL paths

lib/src/executable.dart

@@ -4,51 +4,43 @@ import 'dart:io';
 import 'package:analyzer/dart/analysis/utilities.dart';
 import 'package:args/command_runner.dart';
 import 'package:dart_dev/dart_dev.dart';
-import 'package:dart_dev/src/dart_dev_tool.dart';
-import 'package:dart_dev/src/utils/format_tool_builder.dart';
-import 'package:dart_dev/src/utils/get_dart_version_comment.dart';
-import 'package:dart_dev/src/utils/parse_flag_from_args.dart';
 import 'package:io/ansi.dart';
 import 'package:io/io.dart' show ExitCode;
 import 'package:logging/logging.dart';
 import 'package:path/path.dart' as p;
 
-import '../utils.dart';
 import 'dart_dev_runner.dart';
 import 'tools/over_react_format_tool.dart';
 import 'utils/assert_dir_is_dart_package.dart';
+import 'utils/cached_pubspec.dart';
+import 'utils/dart_dev_paths.dart';
 import 'utils/dart_tool_cache.dart';
 import 'utils/ensure_process_exit.dart';
+import 'utils/format_tool_builder.dart';
+import 'utils/get_dart_version_comment.dart';
 import 'utils/logging.dart';
+import 'utils/parse_flag_from_args.dart';
 
 typedef _ConfigGetter = Map<String, DevTool> Function();
 
-final _runScriptPath = p.join(cacheDirPath, 'run.dart');
+final paths = DartDevPaths();
 
-final _runScript = File(_runScriptPath);
-
-final _configPath = p.join('tool', 'dart_dev', 'config.dart');
-
-final _oldDevDartPath = p.join('tool', 'dev.dart');
-
-final _relativeDevDartPath = p.relative(
-  p.absolute(_configPath),
-  from: p.absolute(p.dirname(_runScriptPath)),
-);
+final _runScript = File(paths.runScript);
 
 Future<void> run(List<String> args) async {
   attachLoggerToStdio(args);
-  final configExists = File(_configPath).existsSync();
-  final oldDevDartExists = File(_oldDevDartPath).existsSync();
+
+  final configExists = File(paths.config).existsSync();
+  final oldDevDartExists = File(paths.legacyConfig).existsSync();
 
   if (!configExists) {
-    log.fine('No custom `$_configPath` file found; '
+    log.fine('No custom `${paths.config}` file found; '
         'using default config.');
   }
   if (oldDevDartExists) {
     log.warning(yellow.wrap(
-        'dart_dev v3 now expects configuration to be at `$_configPath`,\n'
-        'but `$_oldDevDartPath` still exists. View the guide to see how to upgrade:\n'
+        'dart_dev v3 now expects configuration to be at `${paths.config}`,\n'
+        'but `${paths.legacyConfig}` still exists. View the guide to see how to upgrade:\n'
         'https://github.com/Workiva/dart_dev/blob/master/doc/v3-upgrade-guide.md'));
   }
 
@@ -60,7 +52,7 @@ Future<void> run(List<String> args) async {
 
   generateRunScript();
   final process = await Process.start(
-      Platform.executable, [_runScriptPath, ...args],
+      Platform.executable, [paths.runScript, ...args],
       mode: ProcessStartMode.inheritStdio);
   ensureProcessExit(process);
   exitCode = await process.exitCode;
@@ -70,7 +62,7 @@ Future<void> handleFastFormat(List<String> args) async {
   assertDirIsDartPackage();
 
   DevTool formatTool;
-  final configFile = File(_configPath);
+  final configFile = File(paths.config);
   if (configFile.existsSync()) {
     final toolBuilder = FormatToolBuilder();
     parseString(content: configFile.readAsStringSync())
@@ -119,11 +111,11 @@ bool get shouldWriteRunScript =>
 const _isDartDevNullSafe = false;
 
 String buildDartDevRunScriptContents() {
-  final hasCustomToolDevDart = File(_configPath).existsSync();
+  final hasCustomToolDevDart = File(paths.config).existsSync();
   // If the config has a dart version comment (e.g., if it opts out of null safety),
   // copy it over to the entrypoint so the program is run in that language version.
   var dartVersionComment = hasCustomToolDevDart
-      ? getDartVersionComment(File(_configPath).readAsStringSync())
+      ? getDartVersionComment(File(paths.config).readAsStringSync())
       : null;
   // If dart_dev itself is not null-safe, opt the entrypoint out of null-safety
   // so the entrypoint doesn't fail to run in packages that have opted into null-safety.
@@ -137,7 +129,7 @@ import 'dart:io';
 
 import 'package:dart_dev/src/core_config.dart';
 import 'package:dart_dev/src/executable.dart' as executable;
-${hasCustomToolDevDart ? "import '$_relativeDevDartPath' as custom_dev;" : ""}
+${hasCustomToolDevDart ? "import '${paths.configFromRunScriptForDart}' as custom_dev;" : ""}
 
 void main(List<String> args) async {
   await executable.runWithConfig(args,
@@ -162,7 +154,7 @@ Future<void> runWithConfig(
     config = configGetter();
   } catch (error) {
     stderr
-      ..writeln('Invalid "$_configPath" in ${p.absolute(p.current)}')
+      ..writeln('Invalid "${paths.config}" in ${p.absolute(p.current)}')
       ..writeln()
       ..writeln('It should provide a `Map<String, DevTool> config;` getter,'
           ' but it either does not exist or threw unexpectedly:')

lib/src/utils/dart_dev_paths.dart

@@ -0,0 +1,31 @@
+import 'package:path/path.dart' as p;
+
+/// A collection of paths to files and directories constructed to be compatible
+/// with a given [p.Context].
+class DartDevPaths {
+  final p.Context _context;
+
+  DartDevPaths({p.Context context}) : _context = context ?? p.context;
+
+  String cache([String subPath]) => _context.normalize(
+      _context.joinAll([..._cacheParts, if (subPath != null) subPath]));
+
+  String get _cacheForDart => p.url.joinAll(_cacheParts);
+
+  final List<String> _cacheParts = ['.dart_tool', 'dart_dev'];
+
+  String get config => _context.joinAll(_configParts);
+
+  String get configForDart => p.url.joinAll(_configParts);
+
+  final List<String> _configParts = ['tool', 'dart_dev', 'config.dart'];
+
+  String get configFromRunScriptForDart => p.url.relative(
+        p.url.absolute(configForDart),
+        from: p.url.absolute(_cacheForDart),
+      );
+
+  String get legacyConfig => _context.join('tool', 'dev.dart');
+
+  String get runScript => cache('run.dart');
+}

lib/src/utils/dart_tool_cache.dart

@@ -1,15 +1,9 @@
 import 'dart:io';
 
-import 'package:path/path.dart' as p;
-
-const cacheDirPath = '.dart_tool/dart_dev';
+import 'package:dart_dev/src/utils/dart_dev_paths.dart';
 
 void createCacheDir({String subPath}) {
-  var path = cacheDirPath;
-  if (subPath != null) {
-    path = p.join(path, subPath);
-  }
-  final dir = Directory(path);
+  final dir = Directory(DartDevPaths().cache(subPath));
   if (!dir.existsSync()) {
     dir.createSync(recursive: true);
   }

test/utils/dart_dev_paths_test.dart

@@ -0,0 +1,73 @@
+import 'package:dart_dev/src/utils/dart_dev_paths.dart';
+import 'package:path/path.dart' as p;
+import 'package:test/test.dart';
+
+void main() {
+  group('DartDevPaths', () {
+    group('posix', () {
+      DartDevPaths paths;
+
+      setUp(() {
+        paths = DartDevPaths(context: p.posix);
+      });
+
+      test('cache', () {
+        expect(paths.cache(), '.dart_tool/dart_dev');
+      });
+
+      test('cache with subpath', () {
+        expect(paths.cache('sub/path'), '.dart_tool/dart_dev/sub/path');
+      });
+
+      test('config', () {
+        expect(paths.config, 'tool/dart_dev/config.dart');
+      });
+
+      test('configFromRunScriptForDart', () {
+        expect(paths.configFromRunScriptForDart,
+            '../../tool/dart_dev/config.dart');
+      });
+
+      test('legacyConfig', () {
+        expect(paths.legacyConfig, 'tool/dev.dart');
+      });
+
+      test('runScript', () {
+        expect(paths.runScript, '.dart_tool/dart_dev/run.dart');
+      });
+    });
+
+    group('windows', () {
+      DartDevPaths paths;
+
+      setUp(() {
+        paths = DartDevPaths(context: p.windows);
+      });
+
+      test('cache', () {
+        expect(paths.cache(), r'.dart_tool\dart_dev');
+      });
+
+      test('cache with subpath', () {
+        expect(paths.cache('sub/path'), r'.dart_tool\dart_dev\sub\path');
+      });
+
+      test('config', () {
+        expect(paths.config, r'tool\dart_dev\config.dart');
+      });
+
+      test('configFromRunScriptForDart', () {
+        expect(paths.configFromRunScriptForDart,
+            r'../../tool/dart_dev/config.dart');
+      });
+
+      test('legacyConfig', () {
+        expect(paths.legacyConfig, r'tool\dev.dart');
+      });
+
+      test('runScript', () {
+        expect(paths.runScript, r'.dart_tool\dart_dev\run.dart');
+      });
+    });
+  });
+}