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: replacer_test.go
    path of file: ./repos/caddy/modules/caddyhttp
    
    the code of the file until where you have to start completion: // Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package caddyhttp

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"encoding/pem"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/caddyserver/caddy/v2"
)

func TestHTTPVarReplacement(t *testing.T) {
	req, _ := http.NewRequest(http.MethodGet, "/foo/bar.tar.gz", nil)
	repl := caddy.NewReplacer()
	ctx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, repl)
	req = req.WithContext(ctx)
	req.Host = "example.com:80"
	req.RemoteAddr = "192.168.159.32:1234"

	clientCert := []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)

	block, _ := pem.Decode(clientCert)
	if block == nil {
		t.Fatalf("failed to decode PEM certificate")
	}

	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		t.Fatalf("failed to decode PEM certificate: %v", err)
	}

	req.TLS = &tls.ConnectionState{
		Version:                    tls.VersionTLS13,
		HandshakeComplete:          true,
		ServerName:                 "example.com",
		CipherSuite:                tls.TLS_AES_256_GCM_SHA384,
		PeerCertificates:           []*x509.Certificate{cert},
		NegotiatedPro
    
func TestHTTPVarReplacement(t *testing.T) {
	req, _ := http.NewRequest(http.MethodGet, "/foo/bar.tar.gz", nil)
	repl := caddy.NewReplacer()
	ctx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, repl)
	req = req.WithContext(ctx)
	req.Host = "example.com:80"
	req.RemoteAddr = "192.168.159.32:1234"

	clientCert := []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)

	block, _ := pem.Decode(clientCert)
	if block == nil {
		t.Fatalf("failed to decode PEM certificate")
	}

	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		t.Fatalf("failed to decode PEM certificate: %v", err)
	}

	req.TLS = &tls.ConnectionState{
		Version:                    tls.VersionTLS13,
		HandshakeComplete:          true,
		ServerName:                 "example.com",
		CipherSuite:                tls.TLS_AES_256_GCM_SHA384,
		PeerCertificates:           []*x509.Certificate{cert},
		NegotiatedProtocol:         "h2",
		NegotiatedProtocolIsMutual: true,
	}

	res := httptest.NewRecorder()
	addHTTPVarsToReplacer(repl, req, res)

	for i, tc := range []struct {
		get    string
		expect string
	}{
		{
			get:    "http.request.scheme",
			expect: "https",
		},
		{
			get:    "http.request.method",
			expect: http.MethodGet,
		},
		{
			get:    "http.request.host",
			expect: "example.com",
		},
		{
			get:    "http.request.port",
			expect: "80",
		},
		{
			get:    "http.request.hostport",
			expect: "example.com:80",
		},
		{
			get:    "http.request.remote.host",
			expect: "192.168.159.32",
		},
		{
			get:    "http.request.remote.host/24",
			expect: "192.168.159.0/24",
		},
		{
			get:    "http.request.remote.host/24,32",
			expect: "192.168.159.0/24",
		},
		{
			get:    "http.request.remote.host/999",
			expect: "",
		},
		{
			get:    "http.request.remote.port",
			expect: "1234",
		},
		{
			get:    "http.request.host.labels.0",
			expect: "com",
		},
		{
			get:    "http.request.host.labels.1",
			expect: "example",
		},
		{
			get:    "http.request.host.labels.2",
			expect: "",
		},
		{
			get:    "http.request.uri.path.file",
			expect: "bar.tar.gz",
		},
		{
			get:    "http.request.uri.path.file.base",
			expect: "bar.tar",
		},
		{
			// not ideal, but also most correct, given that files can have dots (example: index.<SHA>.html) TODO: maybe this isn't right..
			get:    "http.request.uri.path.file.ext",
			expect: ".gz",
		},
		{
			get:    "http.request.tls.cipher_suite",
			expect: "TLS_AES_256_GCM_SHA384",
		},
		{
			get:    "http.request.tls.proto",
			expect: "h2",
		},
		{
			get:    "http.request.tls.proto_mutual",
			expect: "true",
		},
		{
			get:    "http.request.tls.resumed",
			expect: "false",
		},
		{
			get:    "http.request.tls.server_name",
			expect: "example.com",
		},
		{
			get:    "http.request.tls.version",
			expect: "tls1.3",
		},
		{
			get:    "http.request.tls.client.fingerprint",
			expect: "9f57b7b497cceacc5459b76ac1c3afedbc12b300e728071f55f84168ff0f7702",
		},
		{
			get:    "http.request.tls.client.issuer",
			expect: "CN=Caddy Test CA",
		},
		{
			get:    "http.request.tls.client.serial",
			expect: "2",
		},
		{
			get:    "http.request.tls.client.subject",
			expect: "CN=client.localdomain",
		},
		{
			get:    "http.request.tls.client.san.dns_names",
			expect: "[localhost]",
		},
		{
			get:    "http.request.tls.client.san.dns_names.0",
			expect: "localhost",
		},
		{
			get:    "http.request.tls.client.san.dns_names.1",
			expect: "",
		},
		{
			get:    "http.request.tls.client.san.ips",
			expect: "[127.0.0.1]",
		},
		{
			get:    "http.request.tls.client.san.ips.0",
			expect: "127.0.0.1",
		},
		{
			get:    "http.request.tls.client.certificate_pem",
			expect: string(clientCert) + "\n", // returned value comes with a newline appended to it
		},
	} {
		actual, got := repl.GetString(tc.get)
		if !got {
			t.Errorf("Test %d: Expected to recognize the placeholder name, but didn't", i)
		}
		if actual != tc.expect {
			t.Errorf("Test %d: Expected %s to be '%s' but got '%s'",
				i, tc.get, tc.expect, actual)
		}
	}
}