diff --git a/test/basic_auth_plug_test.exs b/test/basic_auth_plug_test.exs
new file mode 100644
index 0000000..6153cb5
--- /dev/null
+++ b/test/basic_auth_plug_test.exs
@@ -0,0 +1,15 @@
+defmodule BasicAuthExercise.BasicAuthPlugTest do
+  use ExUnit.Case
+
+  test "not passing :username raises an error" do
+    assert_raise KeyError, fn ->
+      BasicAuth.init(password: "secret")
+    end
+  end
+
+  test "not passing :password raises an error" do
+    assert_raise KeyError, fn ->
+      BasicAuth.init(username: "user")
+    end
+  end
+end