diff --git a/packages/middleware-eventstream/src/middleware-eventstream.integ.spec.ts b/packages/middleware-eventstream/src/middleware-eventstream.integ.spec.ts
index 781f563e53004..b8cf25b96cbcf 100644
--- a/packages/middleware-eventstream/src/middleware-eventstream.integ.spec.ts
+++ b/packages/middleware-eventstream/src/middleware-eventstream.integ.spec.ts
@@ -40,7 +40,14 @@ describe("middleware-eventstream", () => {
 
   describe(RekognitionStreaming.name, () => {
     it("should set streaming headers", async () => {
-      const client = new RekognitionStreaming({ region: "us-west-2", logger });
+      const client = new RekognitionStreaming({
+        region: "us-west-2",
+        logger,
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
 
       requireRequestsFrom(client).toMatch({
         headers: {
diff --git a/packages/middleware-flexible-checksums/src/middleware-flexible-checksums.integ.spec.ts b/packages/middleware-flexible-checksums/src/middleware-flexible-checksums.integ.spec.ts
index 7dae9a2145fb3..5d304c5a467fe 100644
--- a/packages/middleware-flexible-checksums/src/middleware-flexible-checksums.integ.spec.ts
+++ b/packages/middleware-flexible-checksums/src/middleware-flexible-checksums.integ.spec.ts
@@ -138,7 +138,7 @@ describe("middleware-flexible-checksums", () => {
 
           requireRequestsFrom(client).toMatch({
             headers: {
-              "user-agent": new RegExp(`(.*?) m\/${id},E$`),
+              "user-agent": new RegExp(`(.*?) m\/(.*?)${id}(.*?)$`),
             },
           });
 
diff --git a/packages/middleware-sdk-s3/src/s3-express/middleware-s3-express.integ.spec.ts b/packages/middleware-sdk-s3/src/s3-express/middleware-s3-express.integ.spec.ts
index 7b3727f83959a..6273d3938f530 100644
--- a/packages/middleware-sdk-s3/src/s3-express/middleware-s3-express.integ.spec.ts
+++ b/packages/middleware-sdk-s3/src/s3-express/middleware-s3-express.integ.spec.ts
@@ -94,7 +94,7 @@ describe("middleware-s3-express", () => {
 
       requireRequestsFrom(client).toMatch({
         headers: {
-          "user-agent": /(.*?) m\/J,E$/,
+          "user-agent": /(.*?) m\/(.*?)J(.*?)$/,
         },
       });
 
diff --git a/packages/middleware-user-agent/src/middleware-user-agent.integ.spec.ts b/packages/middleware-user-agent/src/middleware-user-agent.integ.spec.ts
index 0289ad462e1d8..657c7b81ca18d 100644
--- a/packages/middleware-user-agent/src/middleware-user-agent.integ.spec.ts
+++ b/packages/middleware-user-agent/src/middleware-user-agent.integ.spec.ts
@@ -30,6 +30,7 @@ describe("middleware-user-agent", () => {
   describe("features", () => {
     it("should detect DDB mapper, account id, and account id mode", async () => {
       const client = new DynamoDB({
+        region: "us-west-2",
         accountIdEndpointMode: async () => "required" as const,
       });
 
diff --git a/packages/middleware-websocket/src/middleware-websocket.integ.spec.ts b/packages/middleware-websocket/src/middleware-websocket.integ.spec.ts
index 926bac4fb6695..d8d9119dc4b7e 100644
--- a/packages/middleware-websocket/src/middleware-websocket.integ.spec.ts
+++ b/packages/middleware-websocket/src/middleware-websocket.integ.spec.ts
@@ -16,6 +16,10 @@ describe("middleware-websocket", () => {
       const client = new RekognitionStreaming({
         region: "us-west-2",
         logger,
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
       });
       requireRequestsFrom(client).toMatch({
         protocol: "wss:",
diff --git a/private/aws-middleware-test/src/middleware-apply-body-checksum.spec.ts b/private/aws-middleware-test/src/middleware-apply-body-checksum.spec.ts
index 6b8ee965e9c3c..d9fd64247a079 100644
--- a/private/aws-middleware-test/src/middleware-apply-body-checksum.spec.ts
+++ b/private/aws-middleware-test/src/middleware-apply-body-checksum.spec.ts
@@ -1,13 +1,18 @@
-import { test as it, describe, expect } from "vitest";
-
 import { S3Control } from "@aws-sdk/client-s3-control";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../aws-util-test/src";
 
 describe("middleware-apply-body-checksum", () => {
   describe(S3Control.name, () => {
     it("should add body-checksum", async () => {
-      const client = new S3Control({ region: "us-west-2" });
+      const client = new S3Control({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-md5": /^.{22}(==)?$/i,
diff --git a/private/aws-middleware-test/src/middleware-content-length.spec.ts b/private/aws-middleware-test/src/middleware-content-length.spec.ts
index 2c9d73db112b4..95b19fc468c62 100644
--- a/private/aws-middleware-test/src/middleware-content-length.spec.ts
+++ b/private/aws-middleware-test/src/middleware-content-length.spec.ts
@@ -1,15 +1,20 @@
-import { test as it, describe, expect } from "vitest";
-
 import { AccessAnalyzer } from "@aws-sdk/client-accessanalyzer";
 import { S3 } from "@aws-sdk/client-s3";
 import { XRay } from "@aws-sdk/client-xray";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../../private/aws-util-test/src";
 
 describe("middleware-content-length", () => {
   describe(AccessAnalyzer.name, () => {
     it("should not add content-length if no body", async () => {
-      const client = new AccessAnalyzer({ region: "us-west-2" });
+      const client = new AccessAnalyzer({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-length": /undefined/,
@@ -24,7 +29,13 @@ describe("middleware-content-length", () => {
     });
 
     it("should add content-length if body present", async () => {
-      const client = new AccessAnalyzer({ region: "us-west-2" });
+      const client = new AccessAnalyzer({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-length": /106/,
@@ -42,7 +53,13 @@ describe("middleware-content-length", () => {
 
   describe(S3.name, () => {
     it("should not add content-length if no body", async () => {
-      const client = new S3({ region: "us-west-2" });
+      const client = new S3({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-length": /undefined/,
@@ -58,7 +75,13 @@ describe("middleware-content-length", () => {
     });
 
     it("should add content-length if body present", async () => {
-      const client = new S3({ region: "us-west-2" });
+      const client = new S3({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-length": /4/,
@@ -77,7 +100,13 @@ describe("middleware-content-length", () => {
 
   describe(XRay.name, () => {
     it("should add content-length if body present", async () => {
-      const client = new XRay({ region: "us-west-2" });
+      const client = new XRay({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         headers: {
           "content-length": /24/,
diff --git a/private/aws-middleware-test/src/middleware-endpoint.spec.ts b/private/aws-middleware-test/src/middleware-endpoint.spec.ts
index c3b504b8da6ed..2f2a8eb5aa8b9 100644
--- a/private/aws-middleware-test/src/middleware-endpoint.spec.ts
+++ b/private/aws-middleware-test/src/middleware-endpoint.spec.ts
@@ -1,7 +1,6 @@
-import { test as it, describe, expect } from "vitest";
-
 import { S3 } from "@aws-sdk/client-s3";
 import { S3Control } from "@aws-sdk/client-s3-control";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../aws-util-test/src";
 
@@ -13,6 +12,10 @@ describe("middleware-endpoint", () => {
     it("should resolve endpoints", async () => {
       const client = new S3({
         region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
         useFipsEndpoint: true,
         useDualstackEndpoint: true,
         useArnRegion: true,
@@ -33,6 +36,10 @@ describe("middleware-endpoint", () => {
     it("should resolve endpoints", async () => {
       const client = new S3Control({
         region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
         useFipsEndpoint: true,
         useDualstackEndpoint: true,
         useArnRegion: true,
diff --git a/private/aws-middleware-test/src/middleware-retry.spec.ts b/private/aws-middleware-test/src/middleware-retry.spec.ts
index 83e13baf61bf5..e36ab8b540f99 100644
--- a/private/aws-middleware-test/src/middleware-retry.spec.ts
+++ b/private/aws-middleware-test/src/middleware-retry.spec.ts
@@ -1,6 +1,5 @@
-import { test as it, describe, expect } from "vitest";
-
 import { Lambda } from "@aws-sdk/client-lambda";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../aws-util-test/src";
 
@@ -9,6 +8,10 @@ describe("middleware-retry", () => {
     it("should set retry headers", async () => {
       const client = new Lambda({
         region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
       });
 
       requireRequestsFrom(client).toMatch({
diff --git a/private/aws-middleware-test/src/middleware-serde.spec.ts b/private/aws-middleware-test/src/middleware-serde.spec.ts
index 89c5e26fcbc18..0d2f4ea3cfe21 100644
--- a/private/aws-middleware-test/src/middleware-serde.spec.ts
+++ b/private/aws-middleware-test/src/middleware-serde.spec.ts
@@ -1,16 +1,21 @@
-import { test as it, describe } from "vitest";
-
 import { EC2 } from "@aws-sdk/client-ec2";
 import { S3 } from "@aws-sdk/client-s3";
 import { SageMaker } from "@aws-sdk/client-sagemaker";
 import { SageMakerRuntime } from "@aws-sdk/client-sagemaker-runtime";
+import { describe, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../aws-util-test/src";
 
 describe("middleware-serde", () => {
   describe(S3.name, () => {
     it("should serialize xml", async () => {
-      const client = new S3({ region: "us-west-2" });
+      const client = new S3({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         method: "PUT",
         hostname: "s3.us-west-2.amazonaws.com",
@@ -55,7 +60,13 @@ describe("middleware-serde", () => {
 
   describe(EC2.name, () => {
     it("should serialize query", async () => {
-      const client = new EC2({ region: "us-west-2" });
+      const client = new EC2({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         method: "POST",
         hostname: "ec2.us-west-2.amazonaws.com",
@@ -79,7 +90,13 @@ describe("middleware-serde", () => {
 
   describe(SageMaker.name, () => {
     it("should serialize json", async () => {
-      const client = new SageMaker({ region: "us-west-2" });
+      const client = new SageMaker({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         method: "POST",
         hostname: "api.sagemaker.us-west-2.amazonaws.com",
@@ -102,7 +119,13 @@ describe("middleware-serde", () => {
 
   describe(SageMakerRuntime.name, () => {
     it("should serialize json", async () => {
-      const client = new SageMakerRuntime({ region: "us-west-2" });
+      const client = new SageMakerRuntime({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         method: "POST",
         hostname: "runtime.sagemaker.us-west-2.amazonaws.com",
diff --git a/private/aws-middleware-test/src/util-stream.spec.ts b/private/aws-middleware-test/src/util-stream.spec.ts
index a069a53c7d875..ca897549397ab 100644
--- a/private/aws-middleware-test/src/util-stream.spec.ts
+++ b/private/aws-middleware-test/src/util-stream.spec.ts
@@ -1,18 +1,23 @@
-import { test as it, describe, expect } from "vitest";
-
 import { Lambda } from "@aws-sdk/client-lambda";
 import { HttpHandler, HttpResponse } from "@smithy/protocol-http";
 import { HttpRequest as IHttpRequest } from "@smithy/types";
 import { Uint8ArrayBlobAdapter } from "@smithy/util-stream";
 import { fromUtf8 } from "@smithy/util-utf8";
 import { Readable } from "stream";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../../aws-util-test/src";
 
 describe("util-stream", () => {
   describe(Lambda.name, () => {
     it("should be uniform between string and Uint8Array payloads", async () => {
-      const client = new Lambda({ region: "us-west-2" });
+      const client = new Lambda({
+        region: "us-west-2",
+        credentials: {
+          accessKeyId: "INTEG",
+          secretAccessKey: "INTEG",
+        },
+      });
       requireRequestsFrom(client).toMatch({
         method: "POST",
         hostname: "lambda.us-west-2.amazonaws.com",
@@ -54,6 +59,10 @@ describe("util-stream", () => {
 
     const lambda = new Lambda({
       region: "us-west-2",
+      credentials: {
+        accessKeyId: "INTEG",
+        secretAccessKey: "INTEG",
+      },
     });
 
     requireRequestsFrom(lambda).toMatch({
diff --git a/private/aws-util-test/src/clients/Weather.integ.spec.ts b/private/aws-util-test/src/clients/Weather.integ.spec.ts
index 2efeb8bcdd95e..56851f77d40ce 100644
--- a/private/aws-util-test/src/clients/Weather.integ.spec.ts
+++ b/private/aws-util-test/src/clients/Weather.integ.spec.ts
@@ -1,6 +1,5 @@
-import { test as it, describe, expect } from "vitest";
-
 import { Weather } from "@aws-sdk/weather";
+import { describe, expect, test as it } from "vitest";
 
 import { requireRequestsFrom } from "../requests/test-http-handler";
 
@@ -12,6 +11,7 @@ describe(Weather.name, () => {
         secretAccessKey: "",
       },
       endpoint: "https://localhost",
+      region: "us-west-2",
     });
 
     requireRequestsFrom(client).toMatch({
diff --git a/private/aws-util-test/src/requests/test-http-handler.ts b/private/aws-util-test/src/requests/test-http-handler.ts
index e27282cd780b8..f4bbe7126e2ff 100644
--- a/private/aws-util-test/src/requests/test-http-handler.ts
+++ b/private/aws-util-test/src/requests/test-http-handler.ts
@@ -28,14 +28,6 @@ export type HttpRequestMatcher = {
   log?: boolean;
 };
 
-/**
- * @internal
- */
-const MOCK_CREDENTIALS = {
-  accessKeyId: "MOCK_ACCESS_KEY_ID",
-  secretAccessKey: "MOCK_SECRET_ACCESS_KEY_ID",
-};
-
 /**
  * Supplied to test clients to assert correct requests.
  * @internal
@@ -47,7 +39,30 @@ export class TestHttpHandler implements HttpHandler {
   private client?: Client<any, any, any>;
   private assertions = 0;
 
-  public constructor(public readonly matcher: HttpRequestMatcher) {}
+  public constructor(public readonly matcher: HttpRequestMatcher) {
+    const RESERVED_ENVIRONMENT_VARIABLES = {
+      AWS_DEFAULT_REGION: 1,
+      AWS_REGION: 1,
+      AWS_PROFILE: 1,
+      AWS_ACCESS_KEY_ID: 1,
+      AWS_SECRET_ACCESS_KEY: 1,
+      AWS_SESSION_TOKEN: 1,
+      AWS_CREDENTIAL_EXPIRATION: 1,
+      AWS_CREDENTIAL_SCOPE: 1,
+      AWS_EC2_METADATA_DISABLED: 1,
+      AWS_WEB_IDENTITY_TOKEN_FILE: 1,
+      AWS_ROLE_ARN: 1,
+      AWS_CONTAINER_CREDENTIALS_FULL_URI: 1,
+      AWS_CONTAINER_CREDENTIALS_RELATIVE_URI: 1,
+      AWS_CONTAINER_AUTHORIZATION_TOKEN: 1,
+      AWS_CONTAINER_AUTHORIZATION_TOKEN_FILE: 1,
+    };
+    for (const key in RESERVED_ENVIRONMENT_VARIABLES) {
+      delete process.env[key];
+    }
+    process.env.AWS_ACCESS_KEY_ID = "INTEGRATION_TEST_MOCK";
+    process.env.AWS_SECRET_ACCESS_KEY = "INTEGRATION_TEST_MOCK";
+  }
 
   /**
    * @param client - to watch for requests.
@@ -58,26 +73,6 @@ export class TestHttpHandler implements HttpHandler {
   public watch(client: Client<any, any, any>, matcher: HttpRequestMatcher = this.matcher) {
     this.client = client;
     this.originalRequestHandler = client.config.requestHandler;
-    // mock credentials to avoid default chain lookup.
-    client.config.credentials = async () => MOCK_CREDENTIALS;
-    client.config.credentialDefaultProvider = () => {
-      return async () => {
-        return MOCK_CREDENTIALS;
-      };
-    };
-    const signerProvider = client.config.signer;
-    if (typeof signerProvider === "function") {
-      client.config.signer = async () => {
-        const _signer = await signerProvider();
-        if (typeof _signer.credentialProvider === "function") {
-          // signer is instance of SignatureV4
-          _signer.credentialProvider = async () => {
-            return MOCK_CREDENTIALS;
-          };
-        }
-        return _signer;
-      };
-    }
 
     client.config.requestHandler = new TestHttpHandler(matcher);
     if (!(client as any)[TestHttpHandler.WATCHER]) {
diff --git a/scripts/turbo/index.js b/scripts/turbo/index.js
index 1bf55e046dc3e..b5640e799e7e4 100644
--- a/scripts/turbo/index.js
+++ b/scripts/turbo/index.js
@@ -28,10 +28,7 @@ const runTurbo = async (task, args, { apiSecret, apiEndpoint, apiSignatureKey }
     });
   } catch (error) {
     console.error("Error running turbo:", error);
-    if (args?.length > 0) {
-      // Retry without additional filters
-      return await runTurbo(task, null, apiSecret, apiEndpoint);
-    }
+    throw error;
   }
 };