Bug 711903 part.1 EventUtils.synthesizeKey() shouldn't dispatch keypress event for modifier keys if the event type isn't specified r=smaug

testing/mochitest/tests/SimpleTest/EventUtils.js

@@ -307,6 +307,40 @@ function _computeKeyCodeFromChar(aChar)
   }
 }
 
+/**
+ * isKeypressFiredKey() returns TRUE if the given key should cause keypress
+ * event when widget handles the native key event.  Otherwise, FALSE.
+ *
+ * aDOMKeyCode should be one of consts of nsIDOMKeyEvent::DOM_VK_*, or a key
+ * name begins with "VK_", or a character.
+ */
+function isKeypressFiredKey(aDOMKeyCode)
+{
+  if (typeof(aDOMKeyCode) == "string") {
+    if (aDOMKeyCode.indexOf("VK_") == 0) {
+      aDOMKeyCode = KeyEvent["DOM_" + aDOMKeyCode];
+      if (!aDOMKeyCode) {
+        throw "Unknown key: " + aDOMKeyCode;
+      }
+    } else {
+      // If the key generates a character, it must cause a keypress event.
+      return true;
+    }
+  }
+  switch (aDOMKeyCode) {
+    case KeyEvent.DOM_VK_SHIFT:
+    case KeyEvent.DOM_VK_CONTROL:
+    case KeyEvent.DOM_VK_ALT:
+    case KeyEvent.DOM_VK_CAPS_LOCK:
+    case KeyEvent.DOM_VK_NUM_LOCK:
+    case KeyEvent.DOM_VK_SCROLL_LOCK:
+    case KeyEvent.DOM_VK_META:
+      return false;
+    default:
+      return true;
+  }
+}
+
 /**
  * Synthesize a key event. It is targeted at whatever would be targeted by an
  * actual keypress by the user, typically the focused element.
@@ -347,9 +381,10 @@ function synthesizeKey(aKey, aEvent, aWindow)
     } else {
       var keyDownDefaultHappened =
           utils.sendKeyEvent("keydown", keyCode, 0, modifiers);
-      // XXX Shouldn't dispatch keypress event if the key is a modifier key.
-      utils.sendKeyEvent("keypress", charCode ? 0 : keyCode, charCode,
-                         modifiers, !keyDownDefaultHappened);
+      if (isKeypressFiredKey(keyCode)) {
+        utils.sendKeyEvent("keypress", charCode ? 0 : keyCode, charCode,
+                           modifiers, !keyDownDefaultHappened);
+      }
       utils.sendKeyEvent("keyup", keyCode, 0, modifiers);
     }
   }