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: tracer_test.go
    path of file: ./repos/kratos/middleware/tracing
    
    the code of the file until where you have to start completion: package tracing

import (
	"context"
	"errors"
	"testing"

	"go.opentelemetry.io/otel/trace"

	"github.com/go-kratos/kratos/v2/internal/testdata/binding"
)

func TestNewTracer(t *testing.T) {
	tr
    
func TestNewTracer(t *testing.T) {
	tracer := NewTracer(trace.SpanKindClient, func(o *options) {
		o.tracerProvider = trace.NewNoopTracerProvider()
	})

	if tracer.kind != trace.SpanKindClient {
		t.Errorf("The tracer kind must be equal to trace.SpanKindClient, %v given.", tracer.kind)
	}

	defer func() {
		if recover() == nil {
			t.Error("The NewTracer with an invalid SpanKindMustCrash must panic")
		}
	}()
	_ = NewTracer(666, func(o *options) {
		o.tracerProvider = trace.NewNoopTracerProvider()
	})
}