Fix maximumSelectionLength being ignored by closeOnSelect

There was a bug where the `maximumSelectionLength` option would not
kick in if the `closeOnSelect` option was enabled. Normally, this
was enabled by someone in their global configuration, but it could
also be seen when somoene selected an option while holding the
meta/ctrl/alt keys. This would implicitly enable the `closeOnSelect`
behaviour, even when it was not globally enabled, and cause the bug.

This fixes that issue by listening to the `select` event which is
triggered whenever an option is selected, and triggers the "maximum
selected" message based on that event. This should now force the
message to be displayed, even when the results did not have to be
queried another time.

Fixes #3514
Fixes #3860
Closes #5333

src/js/select2/data/maximumSelectionLength.js

@@ -7,10 +7,30 @@ define([
     decorated.call(this, $e, options);
   }
 
+  MaximumSelectionLength.prototype.bind =
+    function (decorated, container, $container) {
+      var self = this;
+
+      decorated.call(this, container, $container);
+
+      container.on('select', function () {
+        self._checkIfMaximumSelected();
+      });
+  };
+
   MaximumSelectionLength.prototype.query =
     function (decorated, params, callback) {
       var self = this;
 
+      this._checkIfMaximumSelected(function () {
+        decorated.call(self, params, callback);
+      });
+  };
+
+  MaximumSelectionLength.prototype._checkIfMaximumSelected =
+    function (_, successCallback) {
+      var self = this;
+
       this.current(function (currentData) {
         var count = currentData != null ? currentData.length : 0;
         if (self.maximumSelectionLength > 0 &&
@@ -23,7 +43,10 @@ define([
           });
           return;
         }
-        decorated.call(self, params, callback);
+
+        if (successCallback) {
+          successCallback();
+        }
       });
   };
 

tests/data/maximumSelectionLength-tests.js

@@ -125,3 +125,28 @@ test('triggers when >= 1 selection' , function (assert) {
     assert.ok(false, 'The results should not be queried');
   });
 });
+
+test('triggers after selection' , function (assert) {
+  assert.expect(1);
+
+  var $select = $('#qunit-fixture .multiple');
+
+  var maxOfOneOptions = new Options({
+    maximumSelectionLength: 1
+  });
+
+  var container = new MockContainer();
+  var data = new MaximumSelectionData($select, maxOfOneOptions);
+
+  data.bind(container, null);
+
+  data.on('results:message', function () {
+    assert.ok(true, 'The message should be displayed');
+  });
+
+  $select.val(['One']);
+
+  container.trigger('select', {
+    data: {}
+  });
+});