Improve tests

@@ -48,3 +48,5 @@ test/diff
 ref
 !test/golden/*.pdf
 .flutter-plugins-dependencies
+
+cache_*

@@ -25,6 +25,8 @@ import 'package:pdf/pdf.dart';
 import 'package:pdf/widgets.dart';
 import 'package:test/test.dart';
 
+import 'utils.dart';
+
 class Message {
   Message(this.image, this.sendPort);
 
@@ -32,16 +34,6 @@ class Message {
   final SendPort sendPort;
 }
 
-Future<Uint8List> download(String url) async {
-  final HttpClient client = HttpClient();
-  final HttpClientRequest request = await client.getUrl(Uri.parse(url));
-  final HttpClientResponse response = await request.close();
-  final BytesBuilder builder = await response.fold(
-      BytesBuilder(), (BytesBuilder b, List<int> d) => b..add(d));
-  final List<int> data = builder.takeBytes();
-  return Uint8List.fromList(data);
-}
-
 void compute(Message message) {
   final Document pdf = Document();
 

@@ -16,15 +16,15 @@
 
 // ignore_for_file: omit_local_variable_types
 
-import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
-import 'dart:typed_data';
 
 import 'package:pdf/pdf.dart';
 import 'package:pdf/widgets.dart';
 import 'package:test/test.dart';
 
+import 'utils.dart';
+
 Document pdf;
 PdfImage image;
 
@@ -118,16 +118,6 @@ void main() {
   });
 }
 
-Future<Uint8List> download(String url) async {
-  final HttpClient client = HttpClient();
-  final HttpClientRequest request = await client.getUrl(Uri.parse(url));
-  final HttpClientResponse response = await request.close();
-  final BytesBuilder builder = await response.fold(
-      BytesBuilder(), (BytesBuilder b, List<int> d) => b..add(d));
-  final List<int> data = builder.takeBytes();
-  return Uint8List.fromList(data);
-}
-
 const List<String> images = <String>[
   '/9j/4AAQSkZJRgABAQEA3ADcAAD/4QAiRXhpZgAASUkqAAgAAAABABIBAwABAAAAAQAAAAAAAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKSj/2wBDAQcHBwoIChMKChMoGhYaKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCj/wAARCABQADADASIAAhEBAxEB/8QAFgABAQEAAAAAAAAAAAAAAAAAAAkI/8QAFBABAAAAAAAAAAAAAAAAAAAAAP/EABQBAQAAAAAAAAAAAAAAAAAAAAD/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwDKgAAAAAAAKqAAAAlWAAACqgAJVgAqoAAACVYAKqAAAA//2Q==',
   '/9j/4AAQSkZJRgABAQEA3ADcAAD/4QAiRXhpZgAASUkqAAgAAAABABIBAwABAAAAAgAAAAAAAAD/2wBDAAYEBQYFBAYGBQYHBwYIChAKCgkJChQODwwQFxQYGBcUFhYaHSUfGhsjHBYWICwgIyYnKSopGR8tMC0oMCUoKSj/2wBDAQcHBwoIChMKChMoGhYaKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCj/wAARCABQADADASIAAhEBAxEB/8QAFgABAQEAAAAAAAAAAAAAAAAAAAkI/8QAFBABAAAAAAAAAAAAAAAAAAAAAP/EABQBAQAAAAAAAAAAAAAAAAAAAAD/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwDKgAAAAAKqAAAAlWACqgAJVgAAAqoAAACVYAKqAAAAlWAD/9k=',

+/*
+ * Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// ignore_for_file: omit_local_variable_types
+
+import 'dart:async';
+import 'dart:io';
+import 'dart:math' as math;
+import 'dart:typed_data';
+
+import 'package:pdf/pdf.dart';
+import 'package:pdf/widgets.dart';
+
+Future<Uint8List> download(
+  String url, {
+  bool cache = true,
+  String prefix = 'cache_',
+  String suffix,
+}) async {
+  File file;
+  if (cache) {
+    if (suffix == null) {
+      final int l = url.lastIndexOf('.');
+      if (l >= 0) {
+        suffix = url.substring(l);
+      }
+    }
+    file = File('$prefix${url.hashCode}$suffix');
+    if (file.existsSync()) {
+      return await file.readAsBytes();
+    }
+  }
+
+  print('Downloading $url');
+  final HttpClient client = HttpClient();
+  final HttpClientRequest request = await client.getUrl(Uri.parse(url));
+  final HttpClientResponse response = await request.close();
+  final BytesBuilder builder = await response.fold(
+      BytesBuilder(), (BytesBuilder b, List<int> d) => b..add(d));
+  final List<int> data = builder.takeBytes();
+
+  if (cache) {
+    await file.writeAsBytes(data);
+  }
+  return Uint8List.fromList(data);
+}
+
+PdfImage generateBitmap(PdfDocument pdf, int w, int h) {
+  final Uint32List bm = Uint32List(w * h);
+  final double dw = w.toDouble();
+  final double dh = h.toDouble();
+  for (int y = 0; y < h; y++) {
+    for (int x = 0; x < w; x++) {
+      bm[y * w + x] = (math.sin(x / dw) * 256).toInt() |
+          (math.sin(y / dh) * 256).toInt() << 8 |
+          (math.sin(x / dw * y / dh) * 256).toInt() << 16 |
+          0xff000000;
+    }
+  }
+
+  return PdfImage(
+    pdf,
+    image: bm.buffer.asUint8List(),
+    width: w,
+    height: h,
+  );
+}
+
+Font loadFont(String filename) {
+  final Uint8List data = File(filename).readAsBytesSync();
+  return Font.ttf(data.buffer.asByteData());
+}

@@ -17,35 +17,14 @@
 // ignore_for_file: omit_local_variable_types
 
 import 'dart:io';
-import 'dart:math' as math;
-import 'dart:typed_data';
 
-import 'package:test/test.dart';
 import 'package:pdf/pdf.dart';
 import 'package:pdf/widgets.dart';
+import 'package:test/test.dart';
 
-Document pdf;
+import 'utils.dart';
 
-PdfImage generateBitmap(PdfDocument pdf, int w, int h) {
-  final Uint32List bm = Uint32List(w * h);
-  final double dw = w.toDouble();
-  final double dh = h.toDouble();
-  for (int y = 0; y < h; y++) {
-    for (int x = 0; x < w; x++) {
-      bm[y * w + x] = (math.sin(x / dw) * 256).toInt() |
-          (math.sin(y / dh) * 256).toInt() << 8 |
-          (math.sin(x / dw * y / dh) * 256).toInt() << 16 |
-          0xff000000;
-    }
-  }
-
-  return PdfImage(
-    pdf,
-    image: bm.buffer.asUint8List(),
-    width: w,
-    height: h,
-  );
-}
+Document pdf;
 
 void main() {
   setUpAll(() {

@@ -17,11 +17,12 @@
 // ignore_for_file: omit_local_variable_types
 
 import 'dart:io';
-import 'dart:typed_data';
 
 import 'package:pdf/pdf.dart';
-import 'package:test/test.dart';
 import 'package:pdf/widgets.dart';
+import 'package:test/test.dart';
+
+import 'utils.dart';
 
 Document pdf;
 Font openSans;
@@ -30,11 +31,6 @@ Font roboto;
 Font notoSans;
 Font genyomintw;
 
-Font loadFont(String filename) {
-  final Uint8List data = File(filename).readAsBytesSync();
-  return Font.ttf(data.buffer.asByteData());
-}
-
 void main() {
   setUpAll(() {
     Document.debug = true;