test: fetchPopulation関数のユニットテストを追加

src/tests/population.test.ts

@@ -0,0 +1,59 @@
+import axios from "axios";
+import { fetchPopulation } from "../api/population";
+import { PopulationCategory } from "../types/population";
+
+jest.mock("axios");
+const mockedAxios = axios as jest.Mocked<typeof axios>;
+
+describe("fetchPopulation", () => {
+  it("正常に人口データを取得できる", async () => {
+    const mockData: PopulationCategory[] = [
+      {
+        label: "年少人口",
+        data: [{ year: 1960, value: 1681479, rate: 33.37 }],
+      },
+    ];
+
+    const mockResponse = {
+      message: "success",
+      result: {
+        boundaryYear: 2020,
+        data: mockData,
+      },
+    };
+
+    mockedAxios.get.mockResolvedValue({ status: 200, data: mockResponse });
+
+    const prefCode = "1";
+
+    const result = await fetchPopulation(prefCode);
+
+    expect(result).toEqual(mockData);
+    expect(mockedAxios.get).toHaveBeenCalledWith(
+      `${process.env.REACT_APP_YUMEMI_API_URL}/population/${prefCode}`,
+      {
+        headers: {
+          "X-API-KEY": process.env.REACT_APP_YUMEMI_API_KEY!,
+        },
+      }
+    );
+  });
+
+  it("APIがエラーを返した場合、エラーをスローする", async () => {
+    mockedAxios.get.mockRejectedValue(new Error("API Error"));
+
+    const prefCode = "1";
+
+    await expect(fetchPopulation(prefCode)).rejects.toThrow(
+      "Error fetching population data: Error: API Error"
+    );
+    expect(mockedAxios.get).toHaveBeenCalledWith(
+      `${process.env.REACT_APP_YUMEMI_API_URL}/population/${prefCode}`,
+      {
+        headers: {
+          "X-API-KEY": process.env.REACT_APP_YUMEMI_API_KEY!,
+        },
+      }
+    );
+  });
+});