You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: tracing_test.go
    path of file: ./repos/azure-sdk-for-go/sdk/data/aztables
    
    the code of the file until where you have to start completion: // Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

package aztables

import (
	"context"
	"testing"

	"github.com/Azure/azure-sdk-for-go/sdk/azcore/tracing"
	"github.com/stretchr/testify/require"
)

// NewSpanValidator creates a tracing.Provider that verifies a span was created
    
func (mt *matchingTracer) Start(ctx context.Context, spanName string, kind tracing.SpanKind) (context.Context, tracing.Span) {
	if spanName != mt.matcher.Name {
		return ctx, tracing.Span{}
	}
	// span name matches our matcher, track it
	mt.match = &span{
		name: spanName,
	}
	return ctx, tracing.NewSpan(tracing.SpanImpl{
		End:       mt.match.End,
		SetStatus: mt.match.SetStatus,
	})
}