// expected error when the signature check fails.
	signatureMismatchErr := getAPIError(ErrSignatureDoesNotMatch)
	// expected error the when the uploadID is invalid.
	noSuchUploadErr := getAPIError(ErrNoSuchUpload)
	// expected error the part number marker use in the ListObjectParts request is invalid.
	invalidPartMarkerErr := getAPIError(ErrInvalidPartNumberMarker)

			tc, ok := r.Context().Value(mcontext.ContextTraceKey).(*mcontext.TraceCtxt)
			if ok {
				tc.FuncName = "s3.AppendObject"
				tc.ResponseRecorder.LogErrBody = true
			}

			writeErrorResponse(r.Context(), w, getAPIError(ErrNotImplemented), r.URL)
			return
		}

		tc, ok := r.Context().Value(mcontext.ContextTraceKey).(*mcontext.TraceCtxt)
		if ok {
			tc.FuncName = "s3.ValidRequest"
			tc.ResponseRecorder.LogErrBody = true

	anonReq.Body = readerOne

	// call the HTTP handler.
	apiRouter.ServeHTTP(rec, anonReq)

	// expected error response when the unsigned HTTP request is not permitted.
	accessDenied := getAPIError(ErrAccessDenied).HTTPStatusCode
	if rec.Code != accessDenied {
		t.Fatal(failTestStr(anonTestStr, fmt.Sprintf("Object API Nil Test expected to fail with %d, but failed with %d", accessDenied, rec.Code)))
	}

		// to a meaningful S3 API errors. This is added to aid in
		// debugging unexpected/unhandled errors.
		internalLogIf(ctx, err)
	}

	return apiErr
}

// getAPIError provides API Error for input API error code.
func getAPIError(code APIErrorCode) APIError {
	if apiErr, ok := errorCodes[code]; ok {
		return apiErr
	}
	return errorCodes.ToAPIErr(ErrInternalError)
}