1 files changed, 38 insertions, 0 deletions
diff --git a/browser/components/newtab/test/unit/common/Dedupe.test.js b/browser/components/newtab/test/unit/common/Dedupe.test.js
new file mode 100644
index 0000000000..1c85eafa50
--- /dev/null
+++ b/browser/components/newtab/test/unit/common/Dedupe.test.js
@@ -0,0 +1,38 @@
+import { Dedupe } from "common/Dedupe.sys.mjs";
+
+describe("Dedupe", () => {
+  let instance;
+  beforeEach(() => {
+    instance = new Dedupe();
+  });
+  describe("group", () => {
+    it("should remove duplicates inside the groups", () => {
+      const beforeItems = [
+        [1, 1, 1],
+        [2, 2, 2],
+        [3, 3, 3],
+      ];
+      const afterItems = [[1], [2], [3]];
+      assert.deepEqual(instance.group(...beforeItems), afterItems);
+    });
+    it("should remove duplicates between groups, favouring earlier groups", () => {
+      const beforeItems = [
+        [1, 2, 3],
+        [2, 3, 4],
+        [3, 4, 5],
+      ];
+      const afterItems = [[1, 2, 3], [4], [5]];
+      assert.deepEqual(instance.group(...beforeItems), afterItems);
+    });
+    it("should remove duplicates from groups of objects", () => {
+      instance = new Dedupe(item => item.id);
+      const beforeItems = [
+        [{ id: 1 }, { id: 1 }, { id: 2 }],
+        [{ id: 1 }, { id: 3 }, { id: 2 }],
+        [{ id: 1 }, { id: 2 }, { id: 5 }],
+      ];
+      const afterItems = [[{ id: 1 }, { id: 2 }], [{ id: 3 }], [{ id: 5 }]];
+      assert.deepEqual(instance.group(...beforeItems), afterItems);
+    });
+  });
+});