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: logstash_formatter_test.go
    path of file: ./repos/loginsrv/logging
    
    the code of the file until where you have to start completion: package logging

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/url"
	"testing"

	"github.com/sirupsen/logrus"
)

// Taken from github.com/bshuster-repo/logrus-logstash-hook
// MIT License (MIT)
// Copyright (c) 2016 Boaz Shuster

func TestLogstashFormatter(t *testing.T) {
	lf := LogstashFormatter{Type: "abc"}

	someErr := &url.Error{Op: "Get", URL: "http://example.com", Err: fmt.Errorf("The error")}

	fields := logrus.Fields{
		"message": "def",
		"level":   "ijk",
		"type":    "lmn",
		"one":     1,
		"pi":      3.14,
		"bool":    true,
		"error":   someErr,
	}

	entry := logrus.WithFields(fields)
	entry.Message = "msg"
	entry.Level = logrus.InfoLevel

	b, _ := lf.Format(entry)

	var data map[string]interface{}
	dec := json.NewDecoder(bytes.NewReader(b))
	dec.UseNumber()
	dec.Decode(&data)

	// base fields
	if data["@timestamp"] == "" {
		t.Error("expected @timestamp to be not empty")
	}
	tt := []struct {
		expected string
		key      string
	}{
		// ba
    
func TestLogstashFormatter(t *testing.T) {
	lf := LogstashFormatter{Type: "abc"}

	someErr := &url.Error{Op: "Get", URL: "http://example.com", Err: fmt.Errorf("The error")}

	fields := logrus.Fields{
		"message": "def",
		"level":   "ijk",
		"type":    "lmn",
		"one":     1,
		"pi":      3.14,
		"bool":    true,
		"error":   someErr,
	}

	entry := logrus.WithFields(fields)
	entry.Message = "msg"
	entry.Level = logrus.InfoLevel

	b, _ := lf.Format(entry)

	var data map[string]interface{}
	dec := json.NewDecoder(bytes.NewReader(b))
	dec.UseNumber()
	dec.Decode(&data)

	// base fields
	if data["@timestamp"] == "" {
		t.Error("expected @timestamp to be not empty")
	}
	tt := []struct {
		expected string
		key      string
	}{
		// base fields
		{"1", "@version"},
		{"abc", "type"},
		{"msg", "message"},
		{"info", "level"},
		{someErr.Error(), "error"},
		// substituted fields
		{"def", "fields.message"},
		{"ijk", "fields.level"},
		{"lmn", "fields.type"},
	}
	for _, te := range tt {
		if te.expected != data[te.key] {
			t.Errorf("expected data[%s] to be '%s' but got '%s'", te.key, te.expected, data[te.key])
		}
	}

	// formats
	if json.Number("1") != data["one"] {
		t.Errorf("expected one to be '%v' but got '%v'", json.Number("1"), data["one"])
	}
	if json.Number("3.14") != data["pi"] {
		t.Errorf("expected pi to be '%v' but got '%v'", json.Number("3.14"), data["pi"])
	}
	if true != data["bool"] {
		t.Errorf("expected bool to be '%v' but got '%v'", true, data["bool"])
	}
}