Add a test for a successful redirect (#318)

Author: natebosch

test/io/request_test.dart

@@ -46,6 +46,15 @@ void main() {
     expect(response.statusCode, equals(302));
   });
 
+  test('with redirects', () async {
+    final request = http.Request('GET', serverUrl.resolve('/redirect'));
+    final response = await request.send();
+
+    expect(response.statusCode, equals(200));
+    final bytesString = await response.stream.bytesToString();
+    expect(bytesString, parse(containsPair('path', '/')));
+  });
+
   test('exceeding max redirects', () async {
     final request = http.Request('GET', serverUrl.resolve('/loop?1'))
       ..maxRedirects = 2;