diff --git a/tests/e2e/.gitkeep b/tests/e2e/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/.gitkeep b/tests/integration/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/unit/example_test.ts b/tests/unit/example_test.ts
new file mode 100644
index 0000000..1de45e0
--- /dev/null
+++ b/tests/unit/example_test.ts
@@ -0,0 +1,61 @@
+import { assertEquals, assertExists } from "@std/assert";
+import { mockFetch, restoreFetch } from "../helpers/api_mock.ts";
+import { notes, students } from "../helpers/fixtures.ts";
+import { cleanupDOM, setupDOM } from "../helpers/render.ts";
+
+Deno.test("fixtures - students have expected shape", () => {
+  assertEquals(students.length, 3);
+  assertEquals(students[0].nom, "Dupont");
+  assertExists(students[0].numEtud);
+});
+
+Deno.test("mockFetch - returns mocked data for matching route", async () => {
+  mockFetch({
+    "/students": students,
+    "/notes": notes,
+  });
+
+  try {
+    const res = await fetch("http://localhost/api/students");
+    assertEquals(res.status, 200);
+
+    const data = await res.json();
+    assertEquals(data.length, 3);
+    assertEquals(data[0].nom, "Dupont");
+  } finally {
+    restoreFetch();
+  }
+});
+
+Deno.test("mockFetch - returns 404 for unknown routes", async () => {
+  mockFetch({});
+
+  try {
+    const res = await fetch("http://localhost/api/unknown");
+    assertEquals(res.status, 404);
+  } finally {
+    restoreFetch();
+  }
+});
+
+Deno.test({
+  name: "happy-dom - document is available after setup",
+  sanitizeResources: false,
+  sanitizeOps: false,
+  fn() {
+  setupDOM();
+
+  try {
+    const doc = globalThis.document;
+    assertExists(doc);
+
+    const div = doc.createElement("div");
+    div.textContent = "hello";
+    doc.body.appendChild(div);
+
+    assertEquals(doc.body.textContent, "hello");
+  } finally {
+    cleanupDOM();
+  }
+  },
+});