Add support for IfModifiedSince headers, in http_servers' VirtualDirectory.

pkg/http_server/test/virtual_directory_test.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:io';
 
 import "package:unittest/unittest.dart";
 import "package:http_server/http_server.dart";
 
 
+Future<int> getStatusCode(int port, String path) {
+  return new HttpClient().get('localhost', port, path)
+      .then((request) => request.close())
+      .then((response) => response.drain().then(
+          (_) => response.statusCode));
+}
+
+Future<HttpHeaders> getHeaders(int port, String path) {
+  return new HttpClient().get('localhost', port, path)
+      .then((request) => request.close())
+      .then((response) => response.drain().then(
+          (_) => response.headers));
+}
+
+
 void main() {
   group('serve-root', () {
     test('dir-exists', () {
       expect(HttpServer.bind('localhost', 0).then((server) {
         var dir = new Directory('').createTempSync();
         var virDir = new VirtualDirectory(dir.path);
 
         virDir.serve(server);
 
-        return new HttpClient().get('localhost', server.port, '/')
-            .then((request) => request.close())
-            .then((response) => response.drain().then(
-                (_) => response.statusCode))
+        return getStatusCode(server.port, '/')
             .whenComplete(() {
               server.close();
               dir.deleteSync();
             });
       }), completion(equals(HttpStatus.NOT_FOUND)));
     });
 
     test('dir-not-exists', () {
       expect(HttpServer.bind('localhost', 0).then((server) {
         var dir = new Directory('').createTempSync();
         dir.deleteSync();
         var virDir = new VirtualDirectory(dir.path);
 
         virDir.serve(server);
 
-        return new HttpClient().get('localhost', server.port, '/')
-            .then((request) => request.close())
-            .then((response) => response.drain().then(
-                (_) => response.statusCode))
+        return getStatusCode(server.port, '/')
             .whenComplete(() {
               server.close();
             });
       }), completion(equals(HttpStatus.NOT_FOUND)));
     });
   });
 
   group('serve-file', () {
     group('top-level', () {
       test('file-exists', () {
         expect(HttpServer.bind('localhost', 0).then((server) {
           var dir = new Directory('').createTempSync();
           var file = new File('${dir.path}/file')..createSync();
           var virDir = new VirtualDirectory(dir.path);
 
           virDir.serve(server);
 
-          return new HttpClient().get('localhost', server.port, '/file')
-              .then((request) => request.close())
-              .then((response) => response.drain().then(
-                  (_) => response.statusCode))
+          return getStatusCode(server.port, '/file')
               .whenComplete(() {
                 server.close();
                 file.deleteSync();
                 dir.deleteSync();
               });
         }), completion(equals(HttpStatus.OK)));
       });
 
       test('file-not-exists', () {
         expect(HttpServer.bind('localhost', 0).then((server) {
           var dir = new Directory('').createTempSync();
           var virDir = new VirtualDirectory(dir.path);
 
           virDir.serve(server);
 
-          return new HttpClient().get('localhost', server.port, '/file')
-              .then((request) => request.close())
-              .then((response) => response.drain().then(
-                  (_) => response.statusCode))
+          return getStatusCode(server.port, '/file')
               .whenComplete(() {
                 server.close();
                 dir.deleteSync();
               });
         }), completion(equals(HttpStatus.NOT_FOUND)));
       });
     });
 
     group('in-dir', () {
       test('file-exists', () {
         expect(HttpServer.bind('localhost', 0).then((server) {
           var dir = new Directory('').createTempSync();
           var dir2 = new Directory('${dir.path}/dir')..createSync();
           var file = new File('${dir2.path}/file')..createSync();
           var virDir = new VirtualDirectory(dir.path);
 
           virDir.serve(server);
 
-          return new HttpClient().get('localhost', server.port, '/dir/file')
-              .then((request) => request.close())
-              .then((response) => response.drain().then(
-                  (_) => response.statusCode))
+          return getStatusCode(server.port, '/dir/file')
               .whenComplete(() {
                 server.close();
                 file.deleteSync();
                 dir2.deleteSync();
                 dir.deleteSync();
               });
         }), completion(equals(HttpStatus.OK)));
       });
 
       test('file-not-exists', () {
         expect(HttpServer.bind('localhost', 0).then((server) {
           var dir = new Directory('').createTempSync();
           var dir2 = new Directory('${dir.path}/dir')..createSync();
           var file = new File('${dir.path}/file')..createSync();
           var virDir = new VirtualDirectory(dir.path);
 
           virDir.serve(server);
 
-          return new HttpClient().get('localhost', server.port, '/dir/file')
-              .then((request) => request.close())
-              .then((response) => response.drain().then(
-                  (_) => response.statusCode))
+          return getStatusCode(server.port, '/dir/file')
               .whenComplete(() {
                 server.close();
                 file.deleteSync();
                 dir2.deleteSync();
                 dir.deleteSync();
               });
         }), completion(equals(HttpStatus.NOT_FOUND)));
       });
     });
   });
+
+  group('last-mofidied', () {
+    group('file', () {
+      test('file-exists', () {
+        expect(HttpServer.bind('localhost', 0).then((server) {
+          var dir = new Directory('').createTempSync();
+          var file = new File('${dir.path}/file')..createSync();
+          var virDir = new VirtualDirectory(dir.path);
+
+          virDir.serve(server);
+
+          return getHeaders(server.port, '/file')
+              .then((headers) {
+                expect(headers.value(HttpHeaders.LAST_MODIFIED), isNotNull);
+                return HttpDate.parse(
+                    headers.value(HttpHeaders.LAST_MODIFIED));
+              })
+              .then((lastModified) {
+                return new HttpClient().get('localhost', server.port, '/file')
+                    .then((request) {
+                      request.headers.ifModifiedSince = lastModified;
+                      return request.close();
+                    })
+                    .then((response) => response.drain().then(
+                      (_) => response.statusCode));
+              })
+              .whenComplete(() {
+                server.close();
+                dir.deleteSync(recursive: true);
+              });
+        }), completion(equals(HttpStatus.NOT_MODIFIED)));
+      });
+
+      test('file-changes', () {
+        expect(HttpServer.bind('localhost', 0).then((server) {
+          var dir = new Directory('').createTempSync();
+          var file = new File('${dir.path}/file')..createSync();
+          var virDir = new VirtualDirectory(dir.path);
+
+          virDir.serve(server);
+
+          return getHeaders(server.port, '/file')
+              .then((headers) {
+                expect(headers.value(HttpHeaders.LAST_MODIFIED), isNotNull);
+                return HttpDate.parse(
+                    headers.value(HttpHeaders.LAST_MODIFIED));
+              })
+              .then((lastModified) {
+                // Fake file changed by moving date back in time.
+                lastModified = lastModified.subtract(
+                  const Duration(seconds: 10));
+                return new HttpClient().get('localhost', server.port, '/file')
+                    .then((request) {
+                      request.headers.ifModifiedSince = lastModified;
+                      return request.close();
+                    })
+                    .then((response) => response.drain().then(
+                      (_) => response.statusCode));
+              })
+              .whenComplete(() {
+                server.close();
+                dir.deleteSync(recursive: true);
+              });
+        }), completion(equals(HttpStatus.OK)));
+      });
+    });
+  });
 }