1.2.0

.analysis-options

@@ -0,0 +1,2 @@
+analyzer:
+  strong-mode: true

README.md

@@ -10,7 +10,7 @@ In `pubspec.yaml`:
 
 ```yaml
 dependencies:
-    angel_static: ^1.1.0
+    angel_static: ^1.2.0
 ```
 
 # Usage
@@ -58,3 +58,76 @@ The `VirtualDirectory` API accepts a few named parameters:
 - **callback**: Runs before sending a file to a client. Use this to set headers, etc. If it returns anything other than `null` or `true`,
 then the callback's result will be sent to the user, instead of the file contents.
 - **streamToIO**: If set to `true`, files will be streamed to `res.io`, instead of added to `res.buffer`.. Default is `false`.
+
+# Transformers
+`angel_static` now supports *transformers*. Similarly to `pub serve`, or `package:build`, these
+let you dynamically compile assets before sending them to users. For example, in development, you might
+consider using transformers to compile CSS files, or to even replace `pub serve`.
+Transformers are supported by `VirtualDirectory` and `CachingVirtualDirectory`.
+
+To create a transformer:
+```dart
+class MinifierTransformer {
+  /// Use this to declare outputs, and indicate if your transformer
+  /// will compile a file.
+  @override
+  FileInfo declareOutput(FileInfo file) {
+    // For example, we might only want to minify HTML files.
+    if (!file.extensions.endsWith('.min.html'))
+      return null;
+    else return file.changeExtension('.min.html');
+  }
+  
+  /// Actually compile the asset here.
+  @override
+  FutureOr<FileInfo> transform(FileInfo file) async {
+    return file
+      .changeExtension('.min.html')
+      .changeContent(
+        file.content
+          .transform(UTF8.decoder)
+          .transform(const LineSplitter()
+          .transform(UTF8.encoder))
+      );
+  }
+}
+```
+
+To use it:
+```dart
+configureServer(Angel app) async {
+  var vDir = new CachingVirtualDirectory(
+    transformers: [new MinifierTransformer()]
+  );
+  await app.configure(vDir);
+  
+  // It is suggested that you await `transformersLoaded`.
+  // Otherwise, you may receive 404's on paths that should send a compiled asset.
+  await vDir.transformersLoaded;
+}
+```
+
+## Pre-building
+You can pre-build all your assets with one command:
+
+```dart
+configureServer(Angel app) async {
+  var vDir = new VirtualDirectory(transformers: [...]);
+  await app.configure(vDir);
+  
+  // Build if in production
+  if (app.isProduction) {
+    await vDir.buildToDisk();
+  }
+}
+```
+
+## In Production
+By default, transformers are disabled in production mode.
+To force-enable them:
+
+```dart
+configureServer(Angel app) async {
+  var vDir = new VirtualDirectory(useTransformersInProduction: true, transformers: [...]);
+}
+```

lib/angel_static.dart

@@ -1,5 +1,7 @@
 library angel_static;
 
 export 'src/cache.dart';
+export 'src/file_info.dart';
+export 'src/file_transformer.dart';
 export 'src/serve_static.dart';
 export 'src/virtual_directory.dart';

lib/src/cache.dart

@@ -5,6 +5,8 @@ import 'package:angel_framework/angel_framework.dart';
 import 'package:crypto/crypto.dart';
 import 'package:intl/intl.dart';
 import 'package:mime/mime.dart';
+import 'file_info.dart';
+import 'file_transformer.dart';
 import 'virtual_directory.dart';
 
 final DateFormat _fmt = new DateFormat('EEE, d MMM yyyy HH:mm:ss');
@@ -75,14 +77,16 @@ class CachingVirtualDirectory extends VirtualDirectory {
       this.useWeakEtags: true,
       String publicPath,
       StaticFileCallback callback,
-      bool streamToIO: false})
+      bool streamToIO: false,
+      Iterable<FileTransformer> transformers: const []})
       : super(
             source: source,
             debug: debug == true,
             indexFileNames: indexFileNames ?? ['index.html'],
             publicPath: publicPath ?? '/',
             callback: callback,
-            streamToIO: streamToIO == true);
+            streamToIO: streamToIO == true,
+            transformers: transformers ?? []);
 
   @override
   Future<bool> serveFile(
@@ -112,7 +116,7 @@ class CachingVirtualDirectory extends VirtualDirectory {
 
           if (hasBeenModified) {
             res.statusCode = HttpStatus.NOT_MODIFIED;
-            setCachedHeaders(file, stat, req, res);
+            setCachedHeaders(stat.modified, req, res);
             return new Future.value(false);
           }
         }
@@ -124,7 +128,7 @@ class CachingVirtualDirectory extends VirtualDirectory {
 
           if (ifModifiedSince.compareTo(stat.modified) >= 0) {
             res.statusCode = HttpStatus.NOT_MODIFIED;
-            setCachedHeaders(file, stat, req, res);
+            setCachedHeaders(stat.modified, req, res);
 
             if (_etags.containsKey(file.absolute.path))
               res.headers[HttpHeaders.ETAG] = _etags[file.absolute.path];
@@ -143,7 +147,7 @@ class CachingVirtualDirectory extends VirtualDirectory {
         res.headers
           ..[HttpHeaders.ETAG] = etag
           ..[HttpHeaders.CONTENT_TYPE] = lookupMimeType(file.path);
-        setCachedHeaders(file, stat, req, res);
+        setCachedHeaders(stat.modified, req, res);
 
         if (useWeakEtags == false) {
           res
@@ -160,14 +164,71 @@ class CachingVirtualDirectory extends VirtualDirectory {
   }
 
   void setCachedHeaders(
-      File file, FileStat stat, RequestContext req, ResponseContext res) {
+      DateTime modified, RequestContext req, ResponseContext res) {
     var privacy = accessLevelToString(accessLevel ?? CacheAccessLevel.PUBLIC);
     var expiry = new DateTime.now().add(new Duration(seconds: maxAge ?? 0));
 
     res.headers
       ..[HttpHeaders.CACHE_CONTROL] = '$privacy, max-age=${maxAge ?? 0}'
       ..[HttpHeaders.EXPIRES] = formatDateForHttp(expiry)
-      ..[HttpHeaders.LAST_MODIFIED] = formatDateForHttp(stat.modified);
+      ..[HttpHeaders.LAST_MODIFIED] = formatDateForHttp(modified);
+  }
+
+  @override
+  Future<bool> serveAsset(
+      FileInfo fileInfo, RequestContext req, ResponseContext res) {
+    if (onlyInProduction == true && req.app.isProduction == true) {
+      return super.serveAsset(fileInfo, req, res);
+    }
+
+    if (noCache == true) {
+      res.headers[HttpHeaders.CACHE_CONTROL] = 'private, max-age=0, no-cache';
+      return super.serveAsset(fileInfo, req, res);
+    } else {
+      if (useEtags == true) {
+        var etags = req.headers[HttpHeaders.IF_NONE_MATCH];
+
+        if (etags?.isNotEmpty == true) {
+          bool hasBeenModified = false;
+
+          for (var etag in etags) {
+            if (etag == '*')
+              hasBeenModified = true;
+            else {
+              hasBeenModified = _etags.containsKey(fileInfo.filename) &&
+                  _etags[fileInfo.filename] == etag;
+            }
+          }
+
+          if (hasBeenModified) {
+            res.statusCode = HttpStatus.NOT_MODIFIED;
+            setCachedHeaders(fileInfo.lastModified, req, res);
+            return new Future.value(false);
+          }
+        }
+      }
+    }
+
+    if (req.headers[HttpHeaders.IF_MODIFIED_SINCE] != null) {
+      try {
+        var ifModifiedSince = req.headers.ifModifiedSince;
+
+        if (ifModifiedSince.compareTo(fileInfo.lastModified) >= 0) {
+          res.statusCode = HttpStatus.NOT_MODIFIED;
+          setCachedHeaders(fileInfo.lastModified, req, res);
+
+          if (_etags.containsKey(fileInfo.filename))
+            res.headers[HttpHeaders.ETAG] = _etags[fileInfo.filename];
+
+          return new Future.value(false);
+        }
+      } catch (_) {
+        throw new AngelHttpException.badRequest(
+            message: 'Invalid date for If-Modified-Since header.');
+      }
+    }
+
+    return super.serveAsset(fileInfo, req, res);
   }
 }
 

lib/src/file_info.dart

@@ -0,0 +1,91 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'package:mime/mime.dart';
+import 'package:path/path.dart' as p;
+
+/// Represents information about a file, regardless of whether it exists in the filesystem
+/// or in memory.
+abstract class FileInfo {
+  /// Returns the content of the file.
+  Stream<List<int>> get content;
+
+  /// This file's extension.
+  String get extension;
+
+  /// The name of the file.
+  String get filename;
+
+  /// The time when this file was last modified.
+  DateTime get lastModified;
+
+  /// The file's MIME type.
+  String get mimeType;
+
+  /// Creates a [FileInfo] instance representing a physical file.
+  factory FileInfo.fromFile(File file) => new _FileInfoImpl(
+      () => file.openRead(),
+      file.absolute.path,
+      lookupMimeType(file.path),
+      file.statSync().modified);
+
+  /// Creates a [FileInfo] describing a file that might not even exists to begin with.
+  factory FileInfo.hypothetical(String hypotheticalFileName) =>
+      new _FileInfoImpl(null, hypotheticalFileName,
+          lookupMimeType(hypotheticalFileName), null);
+
+  /// Returns an identical instance, but with a different filename.
+  FileInfo changeFilename(String newFilename);
+
+  /// Returns an identical instance, but with a different extension.
+  FileInfo changeExtension(String newExtension);
+
+  /// Returns an identical instance, but with a different content.
+  FileInfo changeContent(Stream<List<int>> newContent);
+
+  /// Returns an identical instance, but with differnet content, set to the given String.
+  FileInfo changeText(String newText, {Encoding encoding: UTF8});
+
+  /// Returns an identical instance, but with a different MIME type.
+  FileInfo changeMimeType(String newMimeType);
+}
+
+class _FileInfoImpl implements FileInfo {
+  @override
+  Stream<List<int>> get content => getContent();
+
+  @override
+  final String filename, mimeType;
+
+  @override
+  final DateTime lastModified;
+
+  final Function getContent;
+
+  _FileInfoImpl(Stream<List<int>> this.getContent(), this.filename,
+      this.mimeType, this.lastModified);
+
+  @override
+  String get extension => p.extension(filename);
+
+  @override
+  FileInfo changeFilename(String newFilename) =>
+      new _FileInfoImpl(getContent, newFilename, mimeType, lastModified);
+
+  @override
+  FileInfo changeExtension(String newExtension) =>
+      changeFilename(p.withoutExtension(filename) + newExtension);
+
+  @override
+  FileInfo changeContent(Stream<List<int>> newContent) =>
+      new _FileInfoImpl(() => newContent, filename, mimeType, lastModified);
+
+  @override
+  FileInfo changeText(String newText, {Encoding encoding: UTF8}) =>
+      changeContent(new Stream<List<int>>.fromIterable(
+          [(encoding ?? UTF8).encode(newText)]));
+
+  @override
+  FileInfo changeMimeType(String newMimeType) =>
+      new _FileInfoImpl(getContent, filename, newMimeType, lastModified);
+}

lib/src/file_transformer.dart

@@ -0,0 +1,15 @@
+import 'dart:async';
+import 'file_info.dart';
+
+/// A class capable of transforming inputs into new outputs, on-the-fly.
+///
+/// Ex. A transformer that compiles Stylus files.
+abstract class FileTransformer {
+  /// Changes the name of a [file] into what it will be once it is transformed.
+  ///
+  /// If this transformer will not be consume the file, then return `null`.
+  FileInfo declareOutput(FileInfo file);
+
+  /// Transforms an input [file] into a new representation.
+  FutureOr<FileInfo> transform(FileInfo file);
+}

lib/src/virtual_directory.dart

@@ -2,7 +2,12 @@ import 'dart:async';
 import 'dart:io';
 import 'package:angel_framework/angel_framework.dart';
 import 'package:angel_route/angel_route.dart';
+import 'package:cli_util/cli_logging.dart' as cli;
 import 'package:mime/mime.dart';
+import 'package:pool/pool.dart';
+import 'package:watcher/watcher.dart';
+import 'file_info.dart';
+import 'file_transformer.dart';
 
 typedef StaticFileCallback(File file, RequestContext req, ResponseContext res);
 
@@ -28,8 +33,16 @@ String _pathify(String path) {
 /// A static server plug-in.
 class VirtualDirectory implements AngelPlugin {
   final bool debug;
+  Angel _app;
   String _prefix;
   Directory _source;
+  final Completer<Map<String, String>> _transformerLoad =
+      new Completer<Map<String, String>>();
+  final Map<String, String> _transformerMap = {};
+  Pool _transformerMapMutex;
+  final List<FileTransformer> _transformers = [];
+  List<FileTransformer> _transformersCache;
+  StreamSubscription<WatchEvent> _watch;
 
   /// The directory to serve files from.
   Directory get source => _source;
@@ -46,14 +59,35 @@ class VirtualDirectory implements AngelPlugin {
   /// If set to `true`, files will be streamed to `res.io`, instead of added to `res.buffer`.
   final bool streamToIO;
 
+  /// A collection of [FileTransformer] instances that will be used to dynamically compile assets, if any. **READ-ONLY**.
+  List<FileTransformer> get transformers =>
+      _transformersCache ??
+      (_transformersCache =
+          new List<FileTransformer>.unmodifiable(_transformers));
+
+  /// If `true` (default: `false`), then transformers will not be disabled in production.
+  final bool useTransformersInProduction;
+
+  /// Completes when all [transformers] are loaded.
+  Future<Map<String, String>> get transformersLoaded {
+    if ((!_app.isProduction || useTransformersInProduction == true) &&
+        !_transformerLoad.isCompleted)
+      return _transformerLoad.future;
+    else
+      return new Future.value(_transformerMap);
+  }
+
   VirtualDirectory(
       {Directory source,
       this.debug: false,
       this.indexFileNames: const ['index.html'],
       this.publicPath: '/',
       this.callback,
-      this.streamToIO: false}) {
+      this.streamToIO: false,
+      this.useTransformersInProduction: false,
+      Iterable<FileTransformer> transformers: const []}) {
     _prefix = publicPath.replaceAll(_straySlashes, '');
+    this._transformers.addAll(transformers ?? []);
 
     if (source != null) {
       _source = source;
@@ -65,20 +99,79 @@ class VirtualDirectory implements AngelPlugin {
     }
   }
 
-  _printDebug(msg) {
-    if (debug) print(msg);
+  call(Angel app) async {
+    serve(_app = app);
+    app.justBeforeStop.add((_) => close());
   }
 
-  call(Angel app) async => serve(app);
-
   void serve(Router router) {
-    _printDebug('Source directory: ${source.absolute.path}');
-    _printDebug('Public path prefix: "$_prefix"');
+    // _printDebug('Source directory: ${source.absolute.path}');
+    // _printDebug('Public path prefix: "$_prefix"');
     router.get('$publicPath/*',
         (RequestContext req, ResponseContext res) async {
       var path = req.path.replaceAll(_straySlashes, '');
       return servePath(path, req, res);
     });
+
+    if ((!_app.isProduction || useTransformersInProduction == true) &&
+        _transformers.isNotEmpty) {
+      // Create mutex, and watch for file changes
+      _transformerMapMutex = new Pool(1);
+      _transformerMapMutex.request().then((resx) {
+        _buildTransformerMap().then((_) => resx.release());
+      });
+    }
+  }
+
+  close() async {
+    if (!_transformerLoad.isCompleted) {
+      _transformerLoad.completeError(new StateError(
+          'VirtualDirectory was closed before all transformers loaded.'));
+    }
+
+    _transformerMapMutex?.close();
+    _watch?.cancel();
+  }
+
+  Future _buildTransformerMap() async {
+    print('VirtualDirectory is loading transformers...');
+
+    await for (var entity in source.list(recursive: true)) {
+      if (entity is File) {
+        _applyTransformers(entity.absolute.uri.toFilePath());
+      }
+    }
+
+    print('VirtualDirectory finished loading transformers.');
+    _transformerLoad.complete(_transformerMap);
+
+    _watch =
+        new DirectoryWatcher(source.absolute.path).events.listen((e) async {
+      _transformerMapMutex.withResource(() {
+        _applyTransformers(e.path);
+      });
+    });
+  }
+
+  void _applyTransformers(String originalAbsolutePath) {
+    FileInfo file = new FileInfo.fromFile(new File(originalAbsolutePath));
+    FileInfo outFile = file;
+    var wasClaimed = false;
+
+    do {
+      wasClaimed = false;
+      for (var transformer in _transformers) {
+        var claimed = transformer.declareOutput(outFile);
+        if (claimed != null) {
+          outFile = claimed;
+          wasClaimed = true;
+        }
+      }
+    } while (wasClaimed);
+
+    var finalName = outFile.filename;
+    if (finalName?.isNotEmpty == true && outFile != file)
+      _transformerMap[finalName] = originalAbsolutePath;
   }
 
   servePath(String path, RequestContext req, ResponseContext res) async {
@@ -95,23 +188,44 @@ class VirtualDirectory implements AngelPlugin {
 
   Future<bool> serveStat(String absolute, FileStat stat, RequestContext req,
       ResponseContext res) async {
-    if (stat.type == FileSystemEntityType.NOT_FOUND)
-      return true;
-    else if (stat.type == FileSystemEntityType.DIRECTORY)
+    if (stat.type == FileSystemEntityType.DIRECTORY)
       return await serveDirectory(new Directory(absolute), stat, req, res);
     else if (stat.type == FileSystemEntityType.FILE)
       return await serveFile(new File(absolute), stat, req, res);
     else if (stat.type == FileSystemEntityType.LINK) {
       var link = new Link(absolute);
       return await servePath(await link.resolveSymbolicLinks(), req, res);
+    } else if (_transformerMapMutex != null) {
+      var resx = await _transformerMapMutex.request();
+      if (!_transformerMap.containsKey(absolute)) return true;
+      var sourceFile = new File(_transformerMap[absolute]);
+      resx.release();
+      if (!await sourceFile.exists())
+        return true;
+      else {
+        return await serveAsset(new FileInfo.fromFile(sourceFile), req, res);
+      }
     } else
       return true;
   }
 
-  Future<bool> serveFile(
+  Future<bool> serveDirectory(Directory directory, FileStat stat,
+      RequestContext req, ResponseContext res) async {
+    for (String indexFileName in indexFileNames) {
+      final index =
+          new File.fromUri(directory.absolute.uri.resolve(indexFileName));
+      if (await index.exists()) {
+        return await serveFile(index, stat, req, res);
+      }
+    }
+
+    return true;
+  }
+
+  Future<bool> serveFileOld(
       File file, FileStat stat, RequestContext req, ResponseContext res) async {
-    _printDebug('Sending file ${file.absolute.path}...');
-    _printDebug('MIME type for ${file.path}: ${lookupMimeType(file.path)}');
+    // _printDebug('Sending file ${file.absolute.path}...');
+    // _printDebug('MIME type for ${file.path}: ${lookupMimeType(file.path)}');
     res.statusCode = 200;
 
     if (callback != null) {
@@ -135,16 +249,131 @@ class VirtualDirectory implements AngelPlugin {
     return false;
   }
 
-  Future<bool> serveDirectory(Directory directory, FileStat stat,
-      RequestContext req, ResponseContext res) async {
-    for (String indexFileName in indexFileNames) {
-      final index =
-          new File.fromUri(directory.absolute.uri.resolve(indexFileName));
-      if (await index.exists()) {
-        return await serveFile(index, stat, req, res);
+  void _ensureContentTypeAllowed(String mimeType, RequestContext req) {
+    var value = req.headers.value(HttpHeaders.ACCEPT);
+    bool acceptable = value == null ||
+        value.isEmpty ||
+        value.contains(mimeType) ||
+        value.contains('*/*');
+    if (!acceptable)
+      throw new AngelHttpException(
+          new UnsupportedError(
+              'Client requested $value, but server wanted to send $mimeType.'),
+          statusCode: HttpStatus.NOT_ACCEPTABLE,
+          message: '406 Not Acceptable');
+  }
+
+  Future<bool> serveFile(
+      File file, FileStat stat, RequestContext req, ResponseContext res) async {
+    // _printDebug('Sending file ${file.absolute.path}...');
+    // _printDebug('MIME type for ${file.path}: ${lookupMimeType(file.path)}');
+    res.statusCode = 200;
+
+    if (callback != null) {
+      var r = callback(file, req, res);
+      r = r is Future ? await r : r;
+      if (r != null && r != true) return r;
+    }
+
+    var type = lookupMimeType(file.path);
+    _ensureContentTypeAllowed(type, req);
+    res.headers[HttpHeaders.CONTENT_TYPE] = type;
+
+    if (streamToIO == true) {
+      res
+        ..io.headers.set(HttpHeaders.CONTENT_TYPE, lookupMimeType(file.path))
+        ..io.headers.set(HttpHeaders.CONTENT_ENCODING, 'gzip')
+        ..end()
+        ..willCloseItself = true;
+
+      await file.openRead().transform(GZIP.encoder).pipe(res.io);
+    } else
+      await res.sendFile(file);
+    return false;
+  }
+
+  Future<bool> serveAsset(
+      FileInfo fileInfo, RequestContext req, ResponseContext res) async {
+    var file = await compileAsset(fileInfo);
+    if (file == null) return true;
+    _ensureContentTypeAllowed(file.mimeType, req);
+    res.headers[HttpHeaders.CONTENT_TYPE] = file.mimeType;
+    res.statusCode = 200;
+
+    if (streamToIO == true) {
+      res
+        ..statusCode = 200
+        ..io.headers.set(HttpHeaders.CONTENT_TYPE, file.mimeType)
+        ..io.headers.set(HttpHeaders.CONTENT_ENCODING, 'gzip')
+        ..end()
+        ..willCloseItself = true;
+      await file.content.transform(GZIP.encoder).pipe(res.io);
+    } else {
+      await file.content.forEach(res.buffer.add);
+    }
+
+    return false;
+  }
+
+  /// Applies all [_transformers] to an input [file], if any.
+  Future<FileInfo> compileAsset(FileInfo file) async {
+    var iterations = 0;
+    FileInfo result = file;
+    bool wasTransformed = false;
+
+    do {
+      wasTransformed = false;
+      String originalName = file.filename;
+      for (var transformer in _transformers) {
+        if (++iterations >= 100) {
+          print(
+              'VirtualDirectory has tried 100 times to compile ${file.filename}. Perhaps one of your transformers is not changing the output file\'s extension.');
+          throw new AngelHttpException(new StackOverflowError(),
+              statusCode: 500);
+        } else if (iterations < 100) iterations++;
+        var claimed = transformer.declareOutput(result);
+        if (claimed != null) {
+          result = await transformer.transform(result);
+          wasTransformed = true;
         }
       }
 
-    return true;
+      // Don't re-compile infinitely...
+      if (result.filename == originalName) wasTransformed = false;
+    } while (wasTransformed);
+
+    return result == file ? null : result;
+  }
+
+  /// Builds assets to disk using [transformers].
+  Future buildToDisk() async {
+    var l = new cli.Logger.standard();
+    print('Building assets in "${source.absolute.path}"...');
+
+    await for (var entity in source.list(recursive: true)) {
+      if (entity is File) {
+        var p = l.progress('Building "${entity.absolute.path}"');
+
+        try {
+          var asset = new FileInfo.fromFile(entity);
+          var compiled = await compileAsset(asset);
+          if (compiled == null)
+            p.finish(message: '"${entity.absolute.path}" did not require compilation; skipping it.');
+          else {
+            p.finish(
+                message:
+                    'Built "${entity.absolute.path}" to "${compiled.filename}".',
+                showTiming: true);
+          }
+        } on AngelHttpException {
+          // Ignore 500
+        } catch (e, st) {
+          p.finish(message: 'Failed to build "${entity.absolute.path}".');
+          stderr..writeln(e)..writeln(st);
+        }
+      }
+    }
+
+    print('Build of assets in "${source.absolute.path}" complete.');
   }
 }

pubspec.yaml

@@ -2,13 +2,20 @@ name: angel_static
 description: Static server middleware for Angel.
 environment:
   sdk: ">=1.19.0"
-homepage: https://github.com/angel-dart/angel_static
-author: thosakwe <thosakwe@gmail.com>
-version: 1.1.4+2
+homepage: https://github.com/angel-dart/static
+author: Tobe O <thosakwe@gmail.com>
+version: 1.2.0
 dependencies:
   angel_framework: ^1.0.0-dev
+  cli_util: ^0.1.1
+  crypto: ^2.0.0
   intl: ">=0.0.0 <1.0.0"
   mime: ^0.9.3
+  path: ^1.4.2
+  pool: ^1.0.0
+  watcher: ^0.9.7
 dev_dependencies:
+  angel_diagnostics: ^1.0.0
+  angel_test: ^1.0.0
   http: ^0.11.3
   test: ^0.12.13

test/all_test.dart

@@ -1,4 +1,5 @@
 import 'dart:io';
+import 'package:angel_diagnostics/angel_diagnostics.dart';
 import 'package:angel_framework/angel_framework.dart';
 import 'package:angel_static/angel_static.dart';
 import 'package:http/http.dart' show Client;
@@ -24,10 +25,11 @@ main() {
         source: testDir,
         indexFileNames: ['index.php', 'index.txt']));
 
-    app.get('*', 'Fallback');
+    app.after.add('Fallback');
 
     app.dumpTree(showMatchers: true);
 
+    await app.configure(logRequests());
     await app.startServer(InternetAddress.LOOPBACK_IP_V4, 0);
     url = "http://${app.httpServer.address.host}:${app.httpServer.port}";
   });

test/transformer_test.dart

@@ -0,0 +1,41 @@
+import 'dart:async';
+import 'dart:io';
+import 'package:angel_framework/angel_framework.dart';
+import 'package:angel_static/angel_static.dart';
+import 'package:angel_test/angel_test.dart';
+import 'package:test/test.dart';
+
+main() {
+  TestClient client;
+
+  setUp(() async {
+    var app = new Angel();
+    var vDir = new CachingVirtualDirectory(
+        source: new Directory('test'),
+        transformers: [new ExtensionTransformer()]);
+    await app.configure(vDir);
+    await vDir.transformersLoaded.then((map) {
+      print('Loaded transformer map: $map');
+    });
+    client = await connectTo(app);
+  });
+
+  tearDown(() => client.close());
+
+  test('foo', () async {
+    var response = await client.get('/index.ext');
+    print('Response: ${response.body}');
+    expect(response, hasBody('.txt'));
+  });
+}
+
+class ExtensionTransformer implements FileTransformer {
+  @override
+  FileInfo declareOutput(FileInfo file) {
+    return file.extension == '.ext' ? null : file.changeExtension('.ext');
+  }
+
+  @override
+  FutureOr<FileInfo> transform(FileInfo file) =>
+      file.changeText(file.extension).changeExtension('.ext');
+}