if err := checkNewMultipartArgs(ctx, srcBucket, srcObject); err != nil {
		return PartInfo{}, err
	}

	return z.PutObjectPart(ctx, destBucket, destObject, uploadID, partID,
		srcInfo.PutObjReader, dstOpts)
}

		// Test case  1-4.
		// Cases with invalid bucket name.
		{bucketName: ".test", objName: "obj", PartID: 1, expectedError: fmt.Errorf("%s", "Bucket name invalid: .test")},
		{bucketName: "------", objName: "obj", PartID: 1, expectedError: fmt.Errorf("%s", "Bucket name invalid: ------")},
		{
			bucketName: "$this-is-not-valid-too", objName: "obj", PartID: 1,
			expectedError: fmt.Errorf("%s", "Bucket name invalid: $this-is-not-valid-too"),
		},

		var cp []CompletePart
		cumulativeSum := int64(0)
		for i, partLen := range partSizes {
			partID := i + 1
			partSrc := NewDummyDataGen(partLen, cumulativeSum)
			cumulativeSum += partLen
			req, errP := newTestSignedRequestV4(http.MethodPut,
				getPutObjectPartURL("", bucketName, objectName, upID, fmt.Sprintf("%d", partID)),
				partLen, partSrc, creds.AccessKey, creds.SecretKey, metadata)
			if errP != nil {