1 files changed, 47 insertions, 0 deletions
diff --git a/spec/frontend/milestones/utils_spec.js b/spec/frontend/milestones/utils_spec.js
new file mode 100644
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+++ b/spec/frontend/milestones/utils_spec.js
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+import { useFakeDate } from 'helpers/fake_date';
+import { sortMilestonesByDueDate } from '~/milestones/utils';
+
+describe('sortMilestonesByDueDate', () => {
+  useFakeDate(2021, 6, 22);
+  const mockMilestones = [
+    {
+      id: 2,
+    },
+    {
+      id: 1,
+      dueDate: '2021-01-01',
+    },
+    {
+      id: 4,
+      dueDate: '2021-02-01',
+      expired: true,
+    },
+    {
+      id: 3,
+      dueDate: `2021-08-01`,
+    },
+  ];
+
+  describe('sorts milestones', () => {
+    it('expired milestones are kept at the bottom of the list', () => {
+      const sortedMilestones = [...mockMilestones].sort(sortMilestonesByDueDate);
+
+      expect(sortedMilestones[2].id).toBe(mockMilestones[1].id); // milestone with id `1` is expired
+      expect(sortedMilestones[3].id).toBe(mockMilestones[2].id); // milestone with id `4` is expired
+    });
+
+    it('milestones with closest due date are kept at the top of the list', () => {
+      const sortedMilestones = [...mockMilestones].sort(sortMilestonesByDueDate);
+
+      // milestone with id `3` & 2021-08-01 is closest to current date i.e. 2021-07-22
+      expect(sortedMilestones[0].id).toBe(mockMilestones[3].id);
+    });
+
+    it('milestones with no due date are kept between milestones with closest due date and expired milestones', () => {
+      const sortedMilestones = [...mockMilestones].sort(sortMilestonesByDueDate);
+
+      // milestone with id `2` has no due date
+      expect(sortedMilestones[1].id).toBe(mockMilestones[0].id);
+    });
+  });
+});