chore: Add an integration test for SigV4A signing region

IntegrationTests/Services/AWSS3IntegrationTests/SigV4ASigningRegionTest.swift

@@ -0,0 +1,64 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import AWSS3
+import AWSSDKHTTPAuth
+import ClientRuntime
+import Smithy
+import SmithyHTTPAPI
+import SmithyHTTPAuthAPI
+import SmithyTestUtil
+import XCTest
+
+// Checks that S3's rules-based SigV4A operations resolve signing region to "*" using PutObject with MRAP ARN.
+class SigV4ASigningRegionTest: XCTestCase {
+    private var sigv4aClient: S3Client!
+    private var sigv4aConfig: S3Client.S3ClientConfiguration!
+
+    override func setUp() async throws {
+        sigv4aConfig = try await S3Client.S3ClientConfiguration(region: "dummy-region")
+        sigv4aConfig.authSchemes = [SigV4AAuthScheme()]
+        sigv4aConfig.httpClientEngine = ProtocolTestClient() // Mock HTTP client that doesn't actually send a request
+        sigv4aConfig.addInterceptorProvider(SigningRegionAssertInterceptorProvider())
+        sigv4aClient = S3Client(config: sigv4aConfig)
+    }
+
+    func testResolvedSigningRegionIsAsterisk() async throws {
+        do {
+            // Providing input.bucket value in the format of MRAP ARN causes endpoint to resolve to MRAP endpoint with
+            //  auth schemes property that has SigV4A.
+            // Then, when signing properties are resolved by the auth scheme, signing region resolved by the service's
+            //  AuthSchemeResolver, saved in AuthOption, supersedes the one provided in config, saved in context.
+            _ = try await sigv4aClient.putObject(input: PutObjectInput(
+                body: ByteStream.data(Data()),
+                bucket: "arn:aws:s3::123456789012:accesspoint/mfzwi23gnjvgw.mrap", // Dummy ARN for MRAP
+                key: "dummy-key"
+            ))
+        } catch is TestCheckError {
+            // This is the expected error thrown by Mock HTTP client; no-op.
+        }
+    }
+}
+
+class SigningRegionAssertInterceptor<InputType, OutputType>: Interceptor {
+    typealias RequestType = HTTPRequest
+    typealias ResponseType = HTTPResponse
+
+    func readBeforeSigning(context: some AfterSerialization<InputType, RequestType>) async throws {
+        let resolvedSigningRegion = context.getAttributes().selectedAuthScheme?.signingProperties?.get(
+            key: SigningPropertyKeys.signingRegion
+        )
+        XCTAssertNotNil(resolvedSigningRegion)
+        XCTAssertEqual(resolvedSigningRegion!, "*") // Assert that the resolved signing region is "*", as expected.
+    }
+}
+
+class SigningRegionAssertInterceptorProvider: HttpInterceptorProvider {
+  func create<InputType, OutputType>() -> any Interceptor<InputType, OutputType, HTTPRequest, HTTPResponse> {
+      return SigningRegionAssertInterceptor()
+  }
+}