Fix hover-tooltip flickering when mouse re-enters

- is(':visible') seems to be the only reliable check, without a refactoring of how hoverState is used
- tests need improvement

js/tests/unit/tooltip.js

@@ -775,4 +775,65 @@ $(function () {
     $circle.bootstrapTooltip('show')
   })
 
+  test('should not reload the tooltip on subsequent mouseenter events', function () {
+    var titleHtml = function () {
+      var uid = $.fn.bootstrapTooltip.Constructor.prototype.getUID('tooltip')
+      return '<p id="tt-content">' + uid + '</p><p>' + uid + '</p><p>' + uid + '</p>'
+    }
+
+    var $tooltip = $('<span id="tt-outer" rel="tooltip" data-trigger="hover" data-placement="top">some text</span>')
+      .appendTo('#qunit-fixture')
+
+    $tooltip.bootstrapTooltip({
+      html: true,
+      animation: false,
+      trigger: 'hover',
+      delay: { show: 0, hide: 500 },
+      container: $tooltip,
+      title: titleHtml
+    })
+
+    $('#tt-outer').trigger('mouseenter')
+
+    var currentUid = $('#tt-content').text()
+
+    $('#tt-content').trigger('mouseenter')
+    equal(currentUid, $('#tt-content').text())
+  })
+
+  test('should not reload the tooltip if the mouse leaves and re-enters before hiding', function () {
+    var titleHtml = function () {
+      var uid = $.fn.bootstrapTooltip.Constructor.prototype.getUID('tooltip')
+      return '<p id="tt-content">' + uid + '</p><p>' + uid + '</p><p>' + uid + '</p>'
+    }
+
+    var $tooltip = $('<span id="tt-outer" rel="tooltip" data-trigger="hover" data-placement="top">some text</span>')
+      .appendTo('#qunit-fixture')
+
+    $tooltip.bootstrapTooltip({
+      html: true,
+      animation: false,
+      trigger: 'hover',
+      delay: { show: 0, hide: 500 },
+      container: $tooltip,
+      title: titleHtml
+    })
+
+    var obj = $tooltip.data('bs.tooltip')
+
+    $('#tt-outer').trigger('mouseenter')
+
+    var currentUid = $('#tt-content').text()
+
+    $('#tt-outer').trigger('mouseleave')
+    equal(currentUid, $('#tt-content').text())
+
+    ok(obj.hoverState == 'out', 'the tooltip hoverState should be set to "out"')
+
+    $('#tt-content').trigger('mouseenter')
+    ok(obj.hoverState == 'in', 'the tooltip hoverState should be set to "in"')
+
+    equal(currentUid, $('#tt-content').text())
+  })
+
 })

js/tooltip.js

@@ -105,6 +105,11 @@
     var self = obj instanceof this.constructor ?
       obj : $(obj.currentTarget).data('bs.' + this.type)
 
+    if (self && self.$tip && self.$tip.is(':visible')) {
+      self.hoverState = 'in'
+      return
+    }
+
     if (!self) {
       self = new this.constructor(obj.currentTarget, this.getDelegateOptions())
       $(obj.currentTarget).data('bs.' + this.type, self)