diff --git a/codegen-client/src/test/kotlin/software/amazon/smithy/rust/codegen/client/smithy/customizations/HttpAuthDecoratorTest.kt b/codegen-client/src/test/kotlin/software/amazon/smithy/rust/codegen/client/smithy/customizations/HttpAuthDecoratorTest.kt
index 76bb3f90b44..b07a3f825d5 100644
--- a/codegen-client/src/test/kotlin/software/amazon/smithy/rust/codegen/client/smithy/customizations/HttpAuthDecoratorTest.kt
+++ b/codegen-client/src/test/kotlin/software/amazon/smithy/rust/codegen/client/smithy/customizations/HttpAuthDecoratorTest.kt
@@ -9,6 +9,7 @@ import org.junit.jupiter.api.Test
 import software.amazon.smithy.rust.codegen.client.testutil.clientIntegrationTest
 import software.amazon.smithy.rust.codegen.core.rustlang.Attribute
 import software.amazon.smithy.rust.codegen.core.rustlang.CargoDependency
+import software.amazon.smithy.rust.codegen.core.rustlang.raw
 import software.amazon.smithy.rust.codegen.core.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType
@@ -98,6 +99,139 @@ class HttpAuthDecoratorTest {
         }
     }
 
+    @Test
+    fun noAuthCustomAuth() {
+        clientIntegrationTest(TestModels.noSchemes) { ctx, rustCrate ->
+            rustCrate.integrationTest("custom_auth_scheme_works") {
+                val moduleName = ctx.moduleUseName()
+                raw(
+                    """
+                    use aws_smithy_runtime_api::client::auth::static_resolver::StaticAuthSchemeOptionResolver;
+                    use aws_smithy_runtime_api::client::auth::AuthScheme;
+                    use aws_smithy_runtime_api::client::auth::{AuthSchemeId, Sign};
+                    use aws_smithy_runtime_api::client::identity::{
+                        IdentityFuture, ResolveIdentity, SharedIdentityResolver,
+                    };
+                    use aws_smithy_runtime_api::client::runtime_components::RuntimeComponents;
+                    use aws_smithy_runtime_api::client::runtime_components::{
+                        GetIdentityResolver, RuntimeComponentsBuilder,
+                    };
+                    use aws_smithy_runtime_api::client::runtime_plugin::RuntimePlugin;
+                    use aws_smithy_types::config_bag::ConfigBag;
+                    use std::borrow::Cow;
+                    #[derive(Debug)]
+                    struct CustomAuthRuntimePlugin {
+                        components: RuntimeComponentsBuilder,
+                    }
+
+                    impl RuntimePlugin for CustomAuthRuntimePlugin {
+                        fn runtime_components(
+                            &self,
+                            _current_components: &RuntimeComponentsBuilder,
+                        ) -> Cow<'_, RuntimeComponentsBuilder> {
+                            Cow::Borrowed(&self.components)
+                        }
+                    }
+
+                    #[derive(Debug)]
+                    struct TestAuthScheme;
+
+                    impl AuthScheme for TestAuthScheme {
+                        fn scheme_id(&self) -> AuthSchemeId {
+                            todo!()
+                        }
+
+                        fn identity_resolver(
+                            &self,
+                            _identity_resolvers: &dyn GetIdentityResolver,
+                        ) -> Option<SharedIdentityResolver> {
+                            todo!()
+                        }
+
+                        fn signer(&self) -> &dyn Sign {
+                            todo!()
+                        }
+                    }
+
+                    #[derive(Debug)]
+                    struct TestResolver;
+                    impl ResolveIdentity for TestResolver {
+                        fn resolve_identity<'a>(
+                            &'a self,
+                            _runtime_components: &'a RuntimeComponents,
+                            _config_bag: &'a ConfigBag,
+                        ) -> IdentityFuture<'a> {
+                            todo!()
+                        }
+                    }
+
+                    impl CustomAuthRuntimePlugin {
+                        pub fn new() -> Self {
+                            let scheme_id = AuthSchemeId::new("basicauth");
+                            Self {
+                                components: RuntimeComponentsBuilder::new("test-auth-scheme")
+                                    // Register our auth scheme
+                                    .with_auth_scheme(TestAuthScheme)
+                                    // Register our identity resolver with our auth scheme ID
+                                    .with_identity_resolver(
+                                        // This scheme ID needs to match the scheme ID returned in the auth scheme implementation
+                                        scheme_id,
+                                        TestResolver,
+                                    )
+                                    // Set the auth scheme option resolver to always use our basic auth auth scheme
+                                    .with_auth_scheme_option_resolver(Some(StaticAuthSchemeOptionResolver::new(vec![
+                                        scheme_id,
+                                    ]))),
+                            }
+                        }
+                    }
+
+                    #[test]
+                    fn compile() {}
+
+                    """,
+
+                )
+                Attribute.TokioTest.render(this)
+                rustTemplate(
+                    """
+                    async fn apply_custom_auth_scheme() {
+                        let (_guard, rx) = #{capture_test_logs}();
+                        let http_client = #{StaticReplayClient}::new(
+                            vec![#{ReplayEvent}::new(
+                                http::Request::builder()
+                                    .header("authorization", "Basic c29tZS11c2VyOnNvbWUtcGFzcw==")
+                                    .uri("http://localhost:1234/SomeOperation")
+                                    .body(#{SdkBody}::empty())
+                                    .unwrap(),
+                                http::Response::builder().status(200).body(#{SdkBody}::empty()).unwrap(),
+                            )],
+                        );
+                        let config = $moduleName::Config::builder()
+                            .endpoint_url("http://localhost:1234")
+                            .http_client(http_client.clone())
+                            .runtime_plugin(CustomAuthRuntimePlugin::new())
+                            .build();
+                        let client = $moduleName::Client::from_conf(config);
+                        let req = client.some_operation()
+                            .send()
+                            .await;
+
+                        println!("{}", rx.contents());
+                        req.unwrap();
+                        panic!()
+
+
+                    }
+                    """,
+                    "capture_test_logs" to CargoDependency.smithyRuntimeTestUtil(ctx.runtimeConfig).toType()
+                        .resolve("test_util::capture_test_logs::capture_test_logs"),
+                    *codegenScope(ctx.runtimeConfig),
+                )
+            }
+        }
+    }
+
     @Test
     fun apiKeyInQueryString() {
         clientIntegrationTest(TestModels.apiKeyInQueryString) { codegenContext, rustCrate ->
@@ -329,6 +463,29 @@ private object TestModels {
         }
     """.asSmithyModel()
 
+    val noSchemes = """
+        namespace test
+
+        use aws.api#service
+        use aws.protocols#restJson1
+
+        @service(sdkId: "Test Api Key Auth")
+        @restJson1
+        service TestService {
+            version: "2023-01-01",
+            operations: [SomeOperation]
+        }
+
+        structure SomeOutput {
+            someAttribute: Long,
+            someVal: String
+        }
+
+        @http(uri: "/SomeOperation", method: "GET")
+        operation SomeOperation {
+            output: SomeOutput
+        }""".asSmithyModel()
+
     val apiKeyInQueryString = """
         namespace test
 
diff --git a/rust-runtime/aws-smithy-runtime-api/src/client/runtime_components.rs b/rust-runtime/aws-smithy-runtime-api/src/client/runtime_components.rs
index 6871f59f22e..e16b24d4bee 100644
--- a/rust-runtime/aws-smithy-runtime-api/src/client/runtime_components.rs
+++ b/rust-runtime/aws-smithy-runtime-api/src/client/runtime_components.rs
@@ -699,6 +699,9 @@ impl GetIdentityResolver for RuntimeComponents {
 #[cfg(all(test, feature = "test-util"))]
 mod tests {
     use super::{BuildError, RuntimeComponentsBuilder, Tracked};
+    use crate::client::identity::{IdentityFuture, ResolveIdentity};
+    use crate::client::runtime_components::RuntimeComponents;
+    use aws_smithy_types::config_bag::ConfigBag;
 
     #[test]
     #[allow(unreachable_pub)]
@@ -829,4 +832,15 @@ mod tests {
     fn building_test_builder_should_not_panic() {
         let _ = RuntimeComponentsBuilder::for_tests().build(); // should not panic
     }
+
+    struct TestResolver;
+    impl ResolveIdentity for TestResolver {
+        fn resolve_identity<'a>(
+            &'a self,
+            runtime_components: &'a RuntimeComponents,
+            config_bag: &'a ConfigBag,
+        ) -> IdentityFuture<'a> {
+            todo!()
+        }
+    }
 }