add: unit and integration testing

app/test/handlesearch.test.js

@@ -0,0 +1,131 @@
+const { handleSearch } = require("../src/search");
+
+describe("handleSearch", () => {
+  let req;
+  let res;
+
+  beforeEach(() => {
+    req = {
+      query: {}
+    };
+
+    // using .mockReturnThis() because of chainable methods
+    res = {
+      status: jest.fn().mockReturnThis(),
+      send: jest.fn().mockReturnThis(),
+      setHeader: jest.fn()
+    };
+  });
+
+  // clean up the observed data after each test
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  test("returns 400 when query is missing", async () => {
+    global.fetch = jest.fn().mockResolvedValue({
+      json: jest.fn().mockResolvedValue({
+        results: [
+          {
+            url: "https://example.com",
+            title: "Example",
+            content: "Content",
+            irrelevant: "removed"
+          }
+        ]
+      })
+    });
+    
+    await handleSearch(req, res);
+
+    expect(res.status).toHaveBeenCalledWith(400);
+    expect(res.send).toHaveBeenCalledWith("Missing search query");
+    expect(global.fetch).not.toHaveBeenCalled();
+  });
+
+  test("fetches search results and sends filtered JSON", async () => {
+    req.query.query = "nodejs testing";
+
+    global.fetch = jest.fn().mockResolvedValue({
+      json: jest.fn().mockResolvedValue({
+        results: [
+          {
+            url: "https://example.com",
+            title: "Example",
+            content: "Content",
+            score: 0.8
+          }
+        ]
+      })
+    });
+
+    await handleSearch(req, res);
+
+    expect(global.fetch).toHaveBeenCalledTimes(1);
+
+    const [url, options] = global.fetch.mock.calls[0];
+
+    expect(url).toContain("/search?");
+    expect(url).toContain("q=nodejs+testing");
+    expect(url).toContain("engines=startpage");
+    expect(url).toContain("format=json");
+    expect(url).not.toContain("score=0.8");
+
+    expect(options).toEqual({
+      headers: {
+        Accept: "application/json"
+      }
+    });
+
+    expect(res.setHeader).toHaveBeenCalledWith(
+      "Content-Type",
+      "application/json; charset=utf-8"
+    );
+
+    expect(res.setHeader).toHaveBeenCalledWith(
+      "Content-Disposition",
+      'attachment; filename="output.json"'
+    );
+
+    expect(res.send).toHaveBeenCalledWith(
+      JSON.stringify(
+        [
+          {
+            url: "https://example.com",
+            title: "Example",
+            content: "Content"
+          }
+        ],
+        null,
+        2
+      )
+    );
+  });
+
+  test("uses an empty array when the API omits results", async () => {
+    req.query.query = "empty";
+
+    global.fetch = jest.fn().mockResolvedValue({
+      json: jest.fn().mockResolvedValue({})
+    });
+
+    await handleSearch(req, res);
+
+    expect(res.send).toHaveBeenCalledWith("[]");
+  });
+
+  test("returns 500 when fetch fails", async () => {
+    req.query.query = "error";
+
+    global.fetch = jest
+      .fn()
+      .mockRejectedValue(new Error("SearxNG unavailable"));
+
+    await handleSearch(req, res);
+
+    expect(res.status).toHaveBeenCalledWith(500);
+    expect(res.send).toHaveBeenCalledWith(
+      "<p><b>Search failed!<br>See the console for the error.</b></p>"
+    );
+  });
+});