1 files changed, 52 insertions, 0 deletions
diff --git a/spec/javascripts/lib/utils/sticky_spec.js b/spec/javascripts/lib/utils/sticky_spec.js
new file mode 100644
index 00000000000..c3ee3ef9825
--- /dev/null
+++ b/spec/javascripts/lib/utils/sticky_spec.js
@@ -0,0 +1,52 @@
+import { isSticky } from '~/lib/utils/sticky';
+
+describe('sticky', () => {
+  const el = {
+    offsetTop: 0,
+    classList: {},
+  };
+
+  beforeEach(() => {
+    el.offsetTop = 0;
+    el.classList.add = jasmine.createSpy('spy');
+    el.classList.remove = jasmine.createSpy('spy');
+  });
+
+  describe('classList.remove', () => {
+    it('does not call classList.remove when stuck', () => {
+      isSticky(el, 0, 0);
+
+      expect(
+        el.classList.remove,
+      ).not.toHaveBeenCalled();
+    });
+
+    it('calls classList.remove when not stuck', () => {
+      el.offsetTop = 10;
+      isSticky(el, 0, 0);
+
+      expect(
+        el.classList.remove,
+      ).toHaveBeenCalledWith('is-stuck');
+    });
+  });
+
+  describe('classList.add', () => {
+    it('calls classList.add when stuck', () => {
+      isSticky(el, 0, 0);
+
+      expect(
+        el.classList.add,
+      ).toHaveBeenCalledWith('is-stuck');
+    });
+
+    it('does not call classList.add when not stuck', () => {
+      el.offsetTop = 10;
+      isSticky(el, 0, 0);
+
+      expect(
+        el.classList.add,
+      ).not.toHaveBeenCalled();
+    });
+  });
+});