[chromedriver] Add a sanity check during session initiation

chrome/test/chromedriver/session_commands.cc

Index: chrome/test/chromedriver/session_commands.cc
diff --git a/chrome/test/chromedriver/session_commands.cc b/chrome/test/chromedriver/session_commands.cc
index b403124f5d63c31e8d49df11e8063f586ff47d0d..4d8513223a4e579c0582c41dd285be91e8793951 100644
--- a/chrome/test/chromedriver/session_commands.cc
+++ b/chrome/test/chromedriver/session_commands.cc
@@ -12,6 +12,7 @@
 #include "base/logging.h"  // For CHECK macros.
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/values.h"
@@ -105,6 +106,34 @@ scoped_ptr<base::DictionaryValue> CreateCapabilities(Chrome* chrome) {
   return caps.Pass();
 }
 
+Status CheckSessionCreated(Session* session) {
+  WebView* web_view = NULL;
+  Status status = session->GetTargetWindow(&web_view);
+  if (status.IsError())
+    return Status(kSessionNotCreatedException, status);
+
+  status = web_view->ConnectIfNecessary();
+  if (status.IsError())
+    return Status(kSessionNotCreatedException, status);
+
+  base::ListValue args;
+  args.AppendString("ping");
+  scoped_ptr<base::Value> result(new base::StringValue(std::string()));
+  status = web_view->CallFunction(session->GetCurrentFrameId(),
+                                  "function(s){return s.replace('i','o')}",

[stgao, 2015/03/14 00:22:03]

For the purpose of sanity check, maybe a simple "return '1';" is good enough?

[samuong, 2015/03/14 17:17:46]

Done.

+                                  args, &result);
+  if (status.IsError())
+    return Status(kSessionNotCreatedException, status);
+
+  std::string response;
+  if (!result->GetAsString(&response) || response != "pong") {
+    return Status(kSessionNotCreatedException,
+                  base::StringPrintf("unexpected response from browser"));

[stgao, 2015/03/14 00:22:03]

It seems other places use raw strings directly, like line 146 and 189 below. Is
there a special reason to use base::StringPrintf?

[samuong, 2015/03/14 17:17:46]

Done. It's no longer needed, so I've removed it.

+  }
+
+  return Status(kOk);
+}
+
 Status InitSessionHelper(
     const InitSessionParams& bound_params,
     Session* session,
@@ -165,7 +194,7 @@ Status InitSessionHelper(
   session->force_devtools_screenshot = capabilities.force_devtools_screenshot;
   session->capabilities = CreateCapabilities(session->chrome.get());
   value->reset(session->capabilities->DeepCopy());
-  return Status(kOk);
+  return CheckSessionCreated(session);
 }
 
 }  // namespace