diff --git a/lib/warden.rb b/lib/warden.rb
index 777e0e2..5919fb7 100644
--- a/lib/warden.rb
+++ b/lib/warden.rb
@@ -39,6 +39,13 @@ def self.test_mode!
           while blk = Warden._on_next_request.shift
             blk.call(proxy)
           end
+          Warden._test_users.each_value do |(user, opts)|
+            opts = opts.dup
+            scope = opts[:scope] || proxy.config.default_scope
+            unless proxy.session_serializer.stored?(scope)
+              proxy.set_user(user, opts)
+            end
+          end
         end
       end
     end
diff --git a/lib/warden/test/helpers.rb b/lib/warden/test/helpers.rb
index cecbc1b..a14312e 100644
--- a/lib/warden/test/helpers.rb
+++ b/lib/warden/test/helpers.rb
@@ -16,10 +16,8 @@ def self.included(_base)
       # @see Warden::Proxy#set_user
       # @api public
       def login_as(user, opts = {})
-        Warden.on_next_request do |proxy|
-          opts[:event] ||= :authentication
-          proxy.set_user(user, opts)
-        end
+        opts[:event] ||= :authentication
+        Warden._test_users[opts[:scope]] = [user, opts]
       end
 
       # Logs out a user from the session.
@@ -28,6 +26,11 @@ def login_as(user, opts = {})
       # @see Warden::Proxy#logout
       # @api public
       def logout(*scopes)
+        if scopes.empty?
+          Warden._test_users.clear
+        else
+          scopes.each { |s| Warden._test_users.delete(s) }
+        end
         Warden.on_next_request do |proxy|
           proxy.logout(*scopes)
         end
diff --git a/lib/warden/test/warden_helpers.rb b/lib/warden/test/warden_helpers.rb
index 9fa46ec..076376d 100644
--- a/lib/warden/test/warden_helpers.rb
+++ b/lib/warden/test/warden_helpers.rb
@@ -31,6 +31,7 @@ def on_next_request(&blk)
       # @api public
       def test_reset!
         _on_next_request.clear
+        _test_users.clear
       end
 
       # A container for the on_next_request items.
@@ -39,6 +40,14 @@ def _on_next_request
         @_on_next_request ||= []
         @_on_next_request
       end
+
+      # A persistent store of test users keyed by scope.
+      # Unlike _on_next_request, these survive across multiple requests,
+      # preventing race conditions with background requests.
+      # @api private
+      def _test_users
+        @_test_users ||= {}
+      end
     end
   end
 end
diff --git a/spec/warden/test/helpers_spec.rb b/spec/warden/test/helpers_spec.rb
index 187bbd3..913027e 100644
--- a/spec/warden/test/helpers_spec.rb
+++ b/spec/warden/test/helpers_spec.rb
@@ -84,6 +84,79 @@
     expect($captures).to eq([:run])
   end
 
+  it "should persist authentication across multiple requests" do
+    user = "A User"
+    session = {}
+    login_as user
+    app = setup_rack(lambda { |e|
+      $captures << e['warden'].user
+      valid_response
+    })
+    app.call(env_with_params("/", {}, "rack.session" => session))
+    app.call(env_with_params("/", {}, "rack.session" => session))
+    expect($captures).to eq(["A User", "A User"])
+  end
+
+  it "should not lose authentication when another session makes a concurrent request" do
+    alice = "Alice"
+    bob   = "Bob"
+
+    alice_session = {}
+    bob_session   = {}
+
+    app = setup_rack(lambda { |e|
+      $captures << e['warden'].user
+      valid_response
+    })
+
+    # 1. Alice logs in and visits a page — her session is established
+    login_as alice
+    app.call(env_with_params("/", {}, "rack.session" => alice_session))
+
+    # 2. Bob logs in
+    login_as bob
+
+    # 3. A background request from Alice's session (e.g. Turbo Frame fetch)
+    app.call(env_with_params("/turbo-frame", {}, "rack.session" => alice_session))
+
+    # 4. Bob's session makes its first request
+    app.call(env_with_params("/", {}, "rack.session" => bob_session))
+
+    expect($captures).to eq(["Alice", "Alice", "Bob"])
+  end
+
+  it "should allow switching users with logout in between" do
+    session = {}
+    app = setup_rack(lambda { |e|
+      $captures << e['warden'].user
+      valid_response
+    })
+
+    login_as "Alice"
+    app.call(env_with_params("/", {}, "rack.session" => session))
+
+    logout
+    login_as "Bob"
+    app.call(env_with_params("/", {}, "rack.session" => session))
+
+    expect($captures).to eq(["Alice", "Bob"])
+  end
+
+  it "should clear persistent state on logout" do
+    user = "A User"
+    login_as user
+    expect(Warden._test_users).not_to be_empty
+    logout
+    expect(Warden._test_users).to be_empty
+  end
+
+  it "should clear only the specified scope on logout" do
+    login_as "Default User"
+    login_as "Foo User", scope: :foo
+    logout :foo
+    expect(Warden._test_users.keys).to eq([nil])
+  end
+
   describe "#asset_paths" do
     it "should default asset_paths to anything asset path regex" do
       expect(Warden.asset_paths).to eq([/^\/assets\//]      )
diff --git a/spec/warden/test/test_mode_spec.rb b/spec/warden/test/test_mode_spec.rb
index ccb4471..3ebef37 100644
--- a/spec/warden/test/test_mode_spec.rb
+++ b/spec/warden/test/test_mode_spec.rb
@@ -63,6 +63,13 @@
     expect($captures).to eq([])
   end
 
+  it "should clear _test_users when test is reset" do
+    Warden._test_users[:default] = ["A User", { event: :authentication }]
+    expect(Warden._test_users).not_to be_empty
+    Warden.test_reset!
+    expect(Warden._test_users).to be_empty
+  end
+
   context "asset requests" do
     it "should not execute on_next_request blocks if this is an asset request" do
       app = setup_rack(@app)