1 files changed, 35 insertions, 0 deletions
diff --git a/spec/javascripts/lib/utils/dom_utils_spec.js b/spec/javascripts/lib/utils/dom_utils_spec.js
new file mode 100644
index 00000000000..867bf5912d1
--- /dev/null
+++ b/spec/javascripts/lib/utils/dom_utils_spec.js
@@ -0,0 +1,35 @@
+import { addClassIfElementExists } from '~/lib/utils/dom_utils';
+
+describe('DOM Utils', () => {
+  describe('addClassIfElementExists', () => {
+    const className = 'biology';
+    const fixture = `
+      <div class="parent">
+        <div class="child"></div>
+      </div>
+    `;
+
+    let parentElement;
+
+    beforeEach(() => {
+      setFixtures(fixture);
+      parentElement = document.querySelector('.parent');
+    });
+
+    it('adds class if element exists', () => {
+      const childElement = parentElement.querySelector('.child');
+      expect(childElement).not.toBe(null);
+
+      addClassIfElementExists(childElement, className);
+
+      expect(childElement.classList).toContain(className);
+    });
+
+    it('does not throw if element does not exist', () => {
+      const childElement = parentElement.querySelector('.other-child');
+      expect(childElement).toBe(null);
+
+      addClassIfElementExists(childElement, className);
+    });
+  });
+});