Change default spec to JsonWire in test.
diff --git a/test/configs/async_io_config.dart b/test/configs/async_io_config.dart
index a20f1fe..480b0da 100644
--- a/test/configs/async_io_config.dart
+++ b/test/configs/async_io_config.dart
@@ -28,7 +28,7 @@
 
 Future<WebDriver> createTestDriver(
     {Map<String, dynamic> additionalCapabilities,
-    WebDriverSpec spec = WebDriverSpec.Auto}) {
+    WebDriverSpec spec = defaultSpec}) {
   final capabilities = getCapabilities(spec);
   if (additionalCapabilities != null) {
     capabilities.addAll(additionalCapabilities);
diff --git a/test/configs/common_config.dart b/test/configs/common_config.dart
index 0933320..7791bf7 100644
--- a/test/configs/common_config.dart
+++ b/test/configs/common_config.dart
@@ -23,6 +23,8 @@
 final Uri _defaultChromeUri = Uri.parse('http://127.0.0.1:4444/wd/hub/');
 final Uri _defaultFirefoxUri = Uri.parse('http://127.0.0.1:4445/');
 
+const WebDriverSpec defaultSpec = WebDriverSpec.JsonWire;
+
 final Matcher isRectangle = const TypeMatcher<Rectangle<int>>();
 final Matcher isPoint = const TypeMatcher<Point<int>>();
 
diff --git a/test/configs/sync_io_config.dart b/test/configs/sync_io_config.dart
index de25457..5c9ce74 100644
--- a/test/configs/sync_io_config.dart
+++ b/test/configs/sync_io_config.dart
@@ -29,7 +29,7 @@
 
 WebDriver createTestDriver(
     {Map<String, dynamic> additionalCapabilities,
-    WebDriverSpec spec = WebDriverSpec.W3c}) {
+    WebDriverSpec spec = defaultSpec}) {
   final capabilities = getCapabilities(spec);
   if (additionalCapabilities != null) {
     capabilities.addAll(additionalCapabilities);