From https://once.com/writebook

test/controllers/sessions_controller_test.rb

@@ -0,0 +1,52 @@
+require "test_helper"
+
+class SessionsControllerTest < ActionDispatch::IntegrationTest
+  ALLOWED_BROWSER    = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Safari/605.1.15"
+  DISALLOWED_BROWSER = "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/114.0"
+
+  test "new" do
+    get new_session_url
+    assert_response :success
+  end
+
+  test "new redirects to first run when no users exist" do
+    User.destroy_all
+
+    get new_session_url
+
+    assert_redirected_to first_run_url
+  end
+
+  test "new denied with incompatible browser" do
+    get new_session_url, env: { "HTTP_USER_AGENT" => DISALLOWED_BROWSER }
+    assert_select "svg", message: /Your browser is not supported/
+  end
+
+  test "new allowed with compatible browser" do
+    get new_session_url, env: { "HTTP_USER_AGENT" => ALLOWED_BROWSER }
+    assert_select "svg", message: /Your browser is not supported/, count: 0
+  end
+
+  test "create with valid credentials" do
+    post session_url, params: { email_address: "david@37signals.com", password: "secret123456" }
+
+    assert_redirected_to root_url
+    assert parsed_cookies.signed[:session_token]
+  end
+
+  test "create with invalid credentials" do
+    post session_url, params: { email_address: "david@37signals.com", password: "wrong" }
+
+    assert_response :unauthorized
+    assert_nil parsed_cookies.signed[:session_token]
+  end
+
+  test "destroy" do
+    sign_in :david
+
+    delete session_url
+
+    assert_redirected_to root_url
+    assert_not cookies[:session_token].present?
+  end
+end