Add tests for the API class

frontend/leeds-beer-quest/src/tests/api.spec.ts

@@ -0,0 +1,73 @@
+import { expect, jest, describe, it } from '@jest/globals';
+import { API } from '../lib/api';
+import { TCategory, TTag } from '../lib/types';
+
+function createFetchMock<T>(returnValue: T) {
+    global.fetch = jest.fn((): Promise<any> => {
+        return Promise.resolve({
+            json: () => Promise.resolve(returnValue)
+        });
+    });
+}
+
+describe("Given the API", () => {
+    describe("when it is calling the category endpoint", () => {
+        it("should return a list of categories", async () => {
+            const api = new API("");
+
+            const categories: TCategory[] = [
+                {
+                    id: 1,
+                    name:"category_one"
+                },
+                {
+                    id: 2,
+                    name:"category_two"
+                },
+                {
+                    id: 3,
+                    name:"category_three"
+                }
+            ];
+            createFetchMock<TCategory[]>(categories);
+
+            const categoriesResponse = await api.getCategories();
+
+            expect(categoriesResponse).toHaveLength(3);
+
+            expect(categoriesResponse[0]).toEqual(categories[0]);
+            expect(categoriesResponse[1]).toEqual(categories[1]);
+            expect(categoriesResponse[2]).toEqual(categories[2]);
+        });
+    });
+
+    describe("when it is calling the tag endpoint", () => {
+        it("should return a list of categories", async () => {
+            const api = new API("");
+
+            const tags: TTag[] = [
+                {
+                    id: 1,
+                    name:"tag_one"
+                },
+                {
+                    id: 2,
+                    name:"tag_two"
+                },
+                {
+                    id: 3,
+                    name:"tag_three"
+                }
+            ];
+            createFetchMock<TTag[]>(tags);
+
+            const tagsResponse = await api.getTags();
+
+            expect(tagsResponse).toHaveLength(3);
+
+            expect(tagsResponse[0]).toEqual(tags[0]);
+            expect(tagsResponse[1]).toEqual(tags[1]);
+            expect(tagsResponse[2]).toEqual(tags[2]);
+        });
+    });
+});