test: add unit test for useFetch

tests/unit/fetch.test.ts

@@ -0,0 +1,27 @@
+import { assertSpyCall, stub, assertSpyCallArgs } from "https://deno.land/[email protected]/testing/mock.ts";
+import { useVersion, useFetch } from "hooks";
+
+
+Deno.test("fetch user-agent header check", async () => {
+  const url = "https://tea.xyz/tea-cli/";
+  const version = useVersion()
+
+  const fetchStub = stub(
+    globalThis,
+    "fetch",
+    () => Promise.resolve(new Response("")),
+  );
+
+  try {
+    await useFetch(url, {});
+  } finally {
+    fetchStub.restore();
+  }
+
+  const expectedUserAgent = `tea.cli/${version}`;
+
+  assertSpyCallArgs(fetchStub, 0, [url, {
+    headers: {"User-Agent": expectedUserAgent}
+  }]);
+
+});