write unit tests for currently implemented code

TypeScript/test/jest/gilded-rose.spec.ts

@@ -1,9 +1,150 @@
 import { Item, GildedRose } from "@/gilded-rose";
 
 describe("Gilded Rose", () => {
-  it("should foo", () => {
-    const gildedRose = new GildedRose([new Item("foo", 0, 0)]);
+  it("should have an empty array as items when no constructor parameter is provided", () => {
+    const gildedRose = new GildedRose();
+    expect(gildedRose.items).toEqual([]);
+  });
+
+  it("should degrade sell inn and quality each day", () => {
+    const gildedRose = new GildedRose([new Item("standard item", 1, 1)]);
+
     const items = gildedRose.updateQuality();
-    expect(items[0].name).toBe("foo");
+
+    expect(items[0]).toMatchObject({
+      name: "standard item",
+      sellIn: 0,
+      quality: 0,
+    });
+  });
+
+  it("should degrade quality twice as fast after sell in date", () => {
+    const gildedRose = new GildedRose([new Item("standard item", 0, 2)]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "standard item",
+      sellIn: -1,
+      quality: 0,
+    });
+  });
+
+  it("should not degrade quality below 0", () => {
+    const gildedRose = new GildedRose([new Item("standard item", 1, 0)]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "standard item",
+      sellIn: 0,
+      quality: 0,
+    });
+  });
+
+  it("should increase quality of Aged Brie as it gets older", () => {
+    const gildedRose = new GildedRose([new Item("Aged Brie", 1, 1)]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Aged Brie",
+      sellIn: 0,
+      quality: 2,
+    });
+  });
+
+  it("should increase quality of Aged Brie twice as fast after sell in date", () => {
+    const gildedRose = new GildedRose([new Item("Aged Brie", 0, 1)]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Aged Brie",
+      sellIn: -1,
+      quality: 3,
+    });
+  });
+
+  it("should never increase quality of Aged Brie over 50", () => {
+    const gildedRose = new GildedRose([new Item("Aged Brie", 0, 50)]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Aged Brie",
+      sellIn: -1,
+      quality: 50,
+    });
+  });
+
+  it("should not change quality of Sulfuras", () => {
+    const gildedRose = new GildedRose([
+      new Item("Sulfuras, Hand of Ragnaros", 0, 80),
+    ]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Sulfuras, Hand of Ragnaros",
+      sellIn: 0,
+      quality: 80,
+    });
+  });
+
+  it("should increase quality of Backstage passes by 1 if sell in date is more than 10 days away", () => {
+    const gildedRose = new GildedRose([
+      new Item("Backstage passes to a TAFKAL80ETC concert", 11, 20),
+    ]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Backstage passes to a TAFKAL80ETC concert",
+      sellIn: 10,
+      quality: 21,
+    });
+  });
+
+  it("should increase quality of Backstage passes by 2 if sell in date is less than 10 days away but more than 5", () => {
+    const gildedRose = new GildedRose([
+      new Item("Backstage passes to a TAFKAL80ETC concert", 9, 20),
+    ]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Backstage passes to a TAFKAL80ETC concert",
+      sellIn: 8,
+      quality: 22,
+    });
+  });
+
+  it("should increase quality of Backstage passes by 3 if sell in date is less than 5 days away", () => {
+    const gildedRose = new GildedRose([
+      new Item("Backstage passes to a TAFKAL80ETC concert", 4, 20),
+    ]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Backstage passes to a TAFKAL80ETC concert",
+      sellIn: 3,
+      quality: 23,
+    });
+  });
+
+  it("should drop quality of Backstage passes to 0 after sell in date", () => {
+    const gildedRose = new GildedRose([
+      new Item("Backstage passes to a TAFKAL80ETC concert", 0, 20),
+    ]);
+
+    const items = gildedRose.updateQuality();
+
+    expect(items[0]).toMatchObject({
+      name: "Backstage passes to a TAFKAL80ETC concert",
+      sellIn: -1,
+      quality: 0,
+    });
   });
 });