diff --git a/tests/auth.spec.ts b/tests/auth.spec.ts
index 1ff6b55..61e5543 100644
--- a/tests/auth.spec.ts
+++ b/tests/auth.spec.ts
@@ -44,6 +44,33 @@ test("Test registration error: password mismatch", async ({ page }) => {
   );
 });
 
+test("Test registration error: dupe user", async ({ page }) => {
+  const user = new User("dupeuser");
+
+  // pre-register user for duplicate user test
+  await user.register(page);
+  await user.logout(page);
+  await expect(page).toHaveTitle("Forgejo: Beyond coding. We forge.");
+
+  await page.getByRole("link", { name: "Register" }).click();
+  await page.waitForURL("**/user/sign_up");
+
+  await page.getByLabel("Username").fill(user.username);
+  await page.getByLabel("Email Address").fill(user.email);
+  await page.getByLabel("Password", { exact: true }).fill(user.password);
+  await page.getByLabel("Confirm Password").fill(user.password);
+
+  await page.getByRole("button", { name: "Register Account" }).click();
+
+  await expect(page).toHaveTitle(
+    "Register - Forgejo: Beyond coding. We forge."
+  );
+  await page.locator(".negative > p:nth-child(1)").waitFor();
+  expect(page.locator(".negative > p:nth-child(1)")).toContainText(
+    "The username is already taken."
+  );
+});
+
 test("Test successful registration", async ({ page }) => {
   const user = new User("register");