// construct HTTP request for copy object.
			req, err = newTestSignedRequestV4(http.MethodPut, getCopyObjectPartURL("", testCase.bucketName, testObject, testCase.uploadID, "1"), 0, nil, testCase.accessKey, testCase.secretKey, nil)
		case testCase.invalidPartNumber:

	if signer == signerV2 {
		return newTestSignedRequestV2(method, urlStr, contentLength, body, accessKey, secretKey, nil)
	}
	return newTestSignedRequestV4(method, urlStr, contentLength, body, accessKey, secretKey, nil)
}

// Returns request with correct signature but with incorrect SHA256.