Fix flutter test target

 class CustomData {
-  const CustomData({this.name = '[your name]'});
+  const CustomData({
+    this.name = '[your name]',
+    this.testing = false,
+  });
 
   final String name;
+
+  final bool testing;
 }

@@ -27,8 +27,12 @@ Future<Uint8List> generateDocument(
     PdfPageFormat format, CustomData data) async {
   final doc = pw.Document(pageMode: PdfPageMode.outlines);
 
-  final font1 = await PdfGoogleFonts.openSansRegular();
-  final font2 = await PdfGoogleFonts.openSansBold();
+  final font1 = data.testing
+      ? pw.Font.helvetica()
+      : await PdfGoogleFonts.openSansRegular();
+  final font2 = data.testing
+      ? pw.Font.helveticaBold()
+      : await PdfGoogleFonts.openSansBold();
   final shape = await rootBundle.loadString('assets/document.svg');
   final swirls = await rootBundle.loadString('assets/swirls2.svg');
 

@@ -7,7 +7,7 @@ import 'package:printing_demo/examples/document.dart';
 
 void main() {
   testWidgets('Pdf Generate the document', (WidgetTester tester) async {
-    const data = CustomData();
+    const data = CustomData(testing: true);
     final doc = await generateDocument(PdfPageFormat.a4, data);
 
     final file = File('document.pdf');

@@ -24,5 +24,9 @@ DeflateCallback defaultDeflate = zlib.encode;
 
 /// The dart:io implementation of [pdfCompute].
 @pragma('vm:prefer-inline')
-Future<R> pdfCompute<R>(Future<R> Function() computation) async =>
-    Isolate.run<R>(computation, debugName: 'dart_pdf');
+Future<R> pdfCompute<R>(Future<R> Function() computation) async {
+  if (Platform.environment.containsKey('FLUTTER_TEST')) {
+    return computation();
+  }
+  return Isolate.run<R>(computation, debugName: 'dart_pdf');
+}