Schedule: Add unit tests to utils/get-random-item.ts

utils/get-random-item.test.ts

@@ -0,0 +1,131 @@
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-var-requires */
+import { getRandomItem } from "./get-random-item";
+
+describe("getRandomItem", () => {
+  describe("single item array", () => {
+    it("should return the only item in a single-item array", () => {
+      const items = ["only-item"];
+      expect(getRandomItem(items)).toBe("only-item");
+    });
+
+    it("should return the only number in a single-item array", () => {
+      const items = [42];
+      expect(getRandomItem(items)).toBe(42);
+    });
+
+    it("should return the only object in a single-item array", () => {
+      const items = [{ id: 1, name: "test" }];
+      expect(getRandomItem(items)).toEqual({ id: 1, name: "test" });
+    });
+  });
+
+  describe("multiple items array", () => {
+    it("should return an item from the array", () => {
+      const items = ["apple", "banana", "cherry"];
+      const result = getRandomItem(items);
+      expect(items).toContain(result);
+    });
+
+    it("should return a number from the array", () => {
+      const items = [1, 2, 3, 4, 5];
+      const result = getRandomItem(items);
+      expect(items).toContain(result);
+    });
+
+    it("should return an object from the array", () => {
+      const items = [
+        { id: 1, name: "first" },
+        { id: 2, name: "second" },
+        { id: 3, name: "third" },
+      ];
+      const result = getRandomItem(items);
+      expect(items).toContainEqual(result);
+    });
+  });
+
+  describe("different data types", () => {
+    it("should work with string arrays", () => {
+      const items = ["a", "b", "c"];
+      const result = getRandomItem(items);
+      expect(typeof result).toBe("string");
+      expect(items).toContain(result);
+    });
+
+    it("should work with number arrays", () => {
+      const items = [10, 20, 30];
+      const result = getRandomItem(items);
+      expect(typeof result).toBe("number");
+      expect(items).toContain(result);
+    });
+
+    it("should work with boolean arrays", () => {
+      const items = [true, false];
+      const result = getRandomItem(items);
+      expect(typeof result).toBe("boolean");
+      expect(items).toContain(result);
+    });
+
+    it("should work with mixed type arrays", () => {
+      const items = [1, "two", true, null, undefined];
+      const result = getRandomItem(items);
+      expect(items).toContain(result);
+    });
+
+    it("should work with object arrays", () => {
+      const items = [
+        { type: "user", id: 1 },
+        { type: "admin", id: 2 },
+      ];
+      const result = getRandomItem(items);
+      expect(items).toContainEqual(result);
+    });
+
+    it("should work with nested arrays", () => {
+      const items = [
+        [1, 2],
+        [3, 4],
+        [5, 6],
+      ];
+      const result = getRandomItem(items);
+      expect(items).toContainEqual(result);
+    });
+  });
+
+  describe("randomness", () => {
+    it("should be able to return different items over multiple calls", () => {
+      const items = ["a", "b", "c", "d", "e"];
+      const results = new Set<string>();
+
+      // Call the function many times to collect results
+      for (let i = 0; i < 100; i++) {
+        results.add(getRandomItem(items));
+      }
+
+      // With 100 calls on 5 items, we should get at least 2 different items
+      // (probability of getting only 1 item is astronomically low)
+      expect(results.size).toBeGreaterThan(1);
+    });
+
+    it("should potentially return all items given enough calls", () => {
+      const items = [1, 2, 3];
+      const results = new Set<number>();
+
+      // Call the function many times
+      for (let i = 0; i < 1000; i++) {
+        results.add(getRandomItem(items));
+      }
+
+      // With 1000 calls on 3 items, we should get all items
+      // (probability of missing an item is extremely low)
+      expect(results.size).toBe(3);
+    });
+  });
+
+  describe("edge cases", () => {
+    it("should handle empty array", () => {
+      const items: string[] = [];
+      const result = getRandomItem(items);
+      expect(result).toBeUndefined();
+    });
+  });
+});