diff --git a/test/controllers/concerns/current_timezone_test.rb b/test/controllers/concerns/current_timezone_test.rb
new file mode 100644
index 000000000..4f0d583fe
--- /dev/null
+++ b/test/controllers/concerns/current_timezone_test.rb
@@ -0,0 +1,17 @@
+require "test_helper"
+
+class CurrentTimezoneTest < ActionDispatch::IntegrationTest
+  test "includes the timezone cookie in the ETag" do
+    cookies[:timezone] = "America/New_York"
+    get user_avatar_path(users(:kevin))
+    etag = response.headers.fetch("ETag")
+
+    get user_avatar_path(users(:kevin)), headers: { "If-None-Match" => etag }
+    assert_equal 304, response.status
+
+    cookies[:timezone] = "America/Los_Angeles"
+    get user_avatar_path(users(:kevin)), headers: { "If-None-Match" => etag }
+    assert_response :success
+    assert_not_equal etag, response.headers.fetch("ETag")
+  end
+end
diff --git a/test/middleware/account_slug_extractor_test.rb b/test/middleware/account_slug_extractor_test.rb
new file mode 100644
index 000000000..79a1c6ab9
--- /dev/null
+++ b/test/middleware/account_slug_extractor_test.rb
@@ -0,0 +1,65 @@
+require "test_helper"
+require "rack/mock"
+
+class AccountSlugExtractorTest < ActiveSupport::TestCase
+  test "moves account prefix from PATH_INFO to SCRIPT_NAME" do
+    account = accounts(:initech)
+    slug = AccountSlug.encode(account.external_account_id)
+
+    captured = call_with_env "/#{slug}/boards"
+
+    assert_equal "/#{slug}", captured.fetch(:script_name)
+    assert_equal "/boards", captured.fetch(:path_info)
+    assert_equal account.external_account_id, captured.fetch(:external_account_id)
+    assert_equal account, captured.fetch(:current_account)
+  end
+
+  test "treats a bare account prefix as the root path" do
+    account = accounts(:initech)
+    slug = AccountSlug.encode(account.external_account_id)
+
+    captured = call_with_env "/#{slug}"
+
+    assert_equal "/#{slug}", captured.fetch(:script_name)
+    assert_equal "/", captured.fetch(:path_info)
+  end
+
+  test "detects the account prefix when already in SCRIPT_NAME" do
+    account = accounts(:initech)
+    slug = AccountSlug.encode(account.external_account_id)
+
+    captured = call_with_env "/boards", "SCRIPT_NAME" => "/#{slug}"
+
+    assert_equal "/#{slug}", captured.fetch(:script_name)
+    assert_equal "/boards", captured.fetch(:path_info)
+    assert_equal account, captured.fetch(:current_account)
+  end
+
+  test "clears Current.account when no account prefix is present" do
+    captured = call_with_env "/boards"
+
+    assert_equal "", captured.fetch(:script_name)
+    assert_equal "/boards", captured.fetch(:path_info)
+    assert_nil captured.fetch(:external_account_id)
+    assert_nil captured.fetch(:current_account)
+  end
+
+  private
+    def call_with_env(path, extra_env = {})
+      captured = {}
+      extra_env = { "action_dispatch.routes" => Rails.application.routes }.merge(extra_env)
+
+      app = ->(env) do
+        captured[:script_name] = env["SCRIPT_NAME"]
+        captured[:path_info] = env["PATH_INFO"]
+        captured[:external_account_id] = env["fizzy.external_account_id"]
+        captured[:current_account] = Current.account
+        [ 200, {}, [ "ok" ] ]
+      end
+
+      middleware = AccountSlug::Extractor.new(app)
+      middleware.call Rack::MockRequest.env_for(path, extra_env.merge(method: "GET"))
+
+      captured
+    end
+end