diff --git a/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts b/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts
new file mode 100644
index 0000000..6a7a50f
--- /dev/null
+++ b/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts
@@ -0,0 +1,61 @@
+import { beforeEach, describe, expect, test } from "@jest/globals";
+import { UnoptimizedInMemoryRepository } from "../../src/repositories/UnoptimizedInMemoryRepository";
+
+// For repositories created in the future, reuse core testing
+// logic from here and differentiate setup (e.g. creating mocks)
+// Do this by creating a function which takes a GetterRepository
+// or GetterSetterRepository instance
+
+describe("UnoptimizedInMemoryRepository", () => {
+  let repository: UnoptimizedInMemoryRepository;
+
+  beforeEach(() => {
+    repository = new UnoptimizedInMemoryRepository();
+  });
+
+  describe("getSystems", () => {
+    test("gets the systems stored in the repository", async () => {
+      const mockSystems = [
+        { id: "1", name: "System A" },
+        { id: "2", name: "System B" },
+      ];
+      await repository.addOrUpdateSystem(mockSystems[0]);
+      await repository.addOrUpdateSystem(mockSystems[1]);
+
+      const result = await repository.getSystems();
+
+      expect(result).toEqual(mockSystems);
+    });
+
+    test("gets an empty list if there are no systems stored", async () => {
+      const result = await repository.getSystems();
+
+      expect(result).toEqual([]);
+    });
+  });
+
+  describe("getSystemById", () => {
+    test("gets a system by the ID if it exists", async () => {
+      const mockSystems = [
+        { id: "1", name: "System A" },
+        { id: "2", name: "System B" },
+        { id: "3", name: "System C" },
+      ];
+      for (const system of mockSystems) {
+        await repository.addOrUpdateSystem(system);
+      }
+
+      const result = await repository.getSystemById("2");
+
+      expect(result).toEqual(mockSystems[1]); // Ensure it retrieves the correct system
+    });
+
+    test("returns null if the system doesn't exist", async () => {
+      const result = await repository.getSystemById("nonexistent-id");
+
+      expect(result).toBeNull();
+    });
+  });
+
+
+});
\ No newline at end of file