Bug 1117001 - xpcshell tests now log console messages. r=chmanchester

testing/xpcshell/head.js

@@ -111,6 +111,30 @@ try {
 }
 catch (e) { }
 
+// Configure a console listener so messages sent to it are logged as part
+// of the test.
+try {
+  let levelNames = {}
+  for (let level of ["debug", "info", "warn", "error"]) {
+    levelNames[Components.interfaces.nsIConsoleMessage[level]] = level;
+  }
+
+  let listener = {
+    QueryInterface : function(iid) {
+      if (!iid.equals(Components.interfaces.nsISupports) &&
+          !iid.equals(Components.interfaces.nsIConsoleListener)) {
+        throw Components.results.NS_NOINTERFACE;
+      }
+      return this;
+    },
+    observe : function (msg) {
+      do_print("CONSOLE_MESSAGE: (" + levelNames[msg.logLevel] + ") " + msg.toString());
+    }
+  };
+  Components.classes["@mozilla.org/consoleservice;1"]
+            .getService(Components.interfaces.nsIConsoleService)
+            .registerListener(listener);
+} catch (e) {}
 /**
  * Date.now() is not necessarily monotonically increasing (insert sob story
  * about times not being the right tool to use for measuring intervals of time,