diff --git a/x-pack/plugins/ml/public/components/chart_tooltip/__tests__/chart_tooltip.js b/x-pack/plugins/ml/public/components/chart_tooltip/__tests__/chart_tooltip.js
new file mode 100644
index 000000000000..5f5c1c465947
--- /dev/null
+++ b/x-pack/plugins/ml/public/components/chart_tooltip/__tests__/chart_tooltip.js
@@ -0,0 +1,26 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import ngMock from 'ng_mock';
+import expect from 'expect.js';
+
+describe('ML - mlChartTooltipService', () => {
+  let mlChartTooltipService;
+
+  beforeEach(ngMock.module('kibana'));
+  beforeEach(() => {
+    ngMock.inject(function ($injector) {
+      mlChartTooltipService = $injector.get('mlChartTooltipService');
+    });
+  });
+
+  it('service API duck typing', () => {
+    expect(mlChartTooltipService).to.be.an('object');
+    expect(mlChartTooltipService.show).to.be.a('function');
+    expect(mlChartTooltipService.hide).to.be.a('function');
+  });
+
+});
diff --git a/x-pack/plugins/ml/public/components/chart_tooltip/chart_tooltip.js b/x-pack/plugins/ml/public/components/chart_tooltip/chart_tooltip.js
index 1a0a66fb4efb..8f2861a0aad3 100644
--- a/x-pack/plugins/ml/public/components/chart_tooltip/chart_tooltip.js
+++ b/x-pack/plugins/ml/public/components/chart_tooltip/chart_tooltip.js
@@ -68,20 +68,20 @@ module.directive('mlChartTooltip', function (mlChartTooltipService) {
           'display': 'block'
         });
       }
+    };
 
-      this.hide = function () {
-        if (this.element !== null) {
-          this.element.css({
-            'opacity': '0',
-          });
+    this.hide = function () {
+      if (this.element !== null) {
+        this.element.css({
+          'opacity': '0',
+        });
 
-          // after the fade out transition has finished, set the display to
-          // none so it doesn't block any mouse events underneath it.
-          this.fadeTimeout = $timeout(() => {
-            this.element.css('display', 'none');
-            this.fadeTimeout = null;
-          }, FADE_TIMEOUT_MS);
-        }
-      };
+        // after the fade out transition has finished, set the display to
+        // none so it doesn't block any mouse events underneath it.
+        this.fadeTimeout = $timeout(() => {
+          this.element.css('display', 'none');
+          this.fadeTimeout = null;
+        }, FADE_TIMEOUT_MS);
+      }
     };
   });