1 files changed, 21 insertions, 0 deletions
diff --git a/spec/frontend/lib/utils/scroll_utils_spec.js b/spec/frontend/lib/utils/scroll_utils_spec.js
new file mode 100644
index 00000000000..d42e25b929c
--- /dev/null
+++ b/spec/frontend/lib/utils/scroll_utils_spec.js
@@ -0,0 +1,21 @@
+import { isScrolledToBottom } from '~/lib/utils/scroll_utils';
+
+describe('isScrolledToBottom', () => {
+  const setScrollGetters = (getters) => {
+    Object.entries(getters).forEach(([name, value]) => {
+      jest.spyOn(Element.prototype, name, 'get').mockReturnValue(value);
+    });
+  };
+
+  it.each`
+    context                                                           | scrollTop | scrollHeight | result
+    ${'returns false when not scrolled to bottom'}                    | ${0}      | ${2000}      | ${false}
+    ${'returns true when scrolled to bottom'}                         | ${1000}   | ${2000}      | ${true}
+    ${'returns true when scrolled to bottom with subpixel precision'} | ${999.25} | ${2000}      | ${true}
+    ${'returns true when cannot scroll'}                              | ${0}      | ${500}       | ${true}
+  `('$context', ({ scrollTop, scrollHeight, result }) => {
+    setScrollGetters({ scrollTop, clientHeight: 1000, scrollHeight });
+
+    expect(isScrolledToBottom()).toBe(result);
+  });
+});