add check about network connectivity; don't run the test if it's not available

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60858 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/image/image.cpp

@@ -107,6 +107,12 @@ void ImageTestCase::LoadFromFile()
 
 void ImageTestCase::LoadFromSocketStream()
 {
+    if (!IsNetworkAvailable())      // implemented in test.cpp
+    {
+        wxLogWarning("No network connectivity; skipping the ImageTestCase::LoadFromSocketStream test unit.");
+        return;
+    }
+
     struct {
         const char* url;
         wxBitmapType type;