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: postgres_test.go
    path of file: ./repos/go-cloud/postgres
    
    the code of the file until where you have to start completion: // Copyright 2019 The Go Cloud Development Kit 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
//
//     https://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 postgres

import (
	"bytes"
	"context"
	"fmt"
	"io/ioutil"
	"net/url"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"runtime"
	"testing"
	"time"
)

func TestOpen(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("Can't use Unix sockets on Windows")
	}
	postgresPath, err := exec.LookPath("postgres")
	if err != nil {
		t.Skip("Can't find postgres:", err)
	}
	initdbPath, err := exec.LookPath("initdb")
	if err != nil {
		t.Skip("Can't find initdb:", err)
	}

	// Create a temporary database data directory.
	currUser, err := user.Current()
	if err != nil {
		t.Fatal(err)
	}
	dir, err := ioutil.TempDir("", "gocloud_postgres_test")
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := os.RemoveAll(dir); err != nil {
			t.Errorf("Cleaning up: %v", err)
		}
	}()
	dataDir := filepath.Join(dir, "data")
	initdbCmd := exec.Command(initdbPath, "-U", currUser.Username, "-D", dataDir)
	initdbOutput := new(bytes.Buffer)
	initdbCmd.Stdout = initdbOutput
	initdbCmd.Stderr = initdbOutput
	err = initdbCmd.Run()
	if err != nil {
		t.Log(initdbOutput)
		t.Fatal(err)
	}

	// Configure the database server to listen on a Unix socket located in the temporary directory.
	socketDir, err := filepath.Abs(filepath.Join(dir, "socket"))
	if err != nil {
		t.Fatal(err)
	}
	if err := os.Mkdir(socketDir, 0777); err != nil {
		t.Fatal(err)
	}
	confData := new(bytes.Buffer)
	fmt.Fprintf(confData, "unix_socket_directories = '%s'\n", socketDir)
	err = ioutil.WriteFile(filepath.Join(dataDir, "postgresql.conf"), confData.Bytes(), 0666)
	if err != nil {
		t.Fatal(err)
	}

	// Start the database server (and arrange for it to be stopped at test end).
	server := exec.Command(postgresPath, "-D", dataDir)
	serverOutput := new(bytes.Buffer)
	server.Stdout = serverOutput
	server.Stderr = serverOutput
	if err := server.Start(); err != nil {
		t.Fatal(err)
	}
	serverSignaled := false
	defer func() {
		if !serverSignaled {
			if err := server.Process.Kill(); err != nil {
				t.Error("Stopping server:", err)
			}
		}
		// Wait for server to exit, but ignore the expected failure error code.
		server.Wait()
		if t.Failed() {
			t.Log(serverOutput)
		}
	}()

	// Now the actual test: can we connect to the database via URL opener?
	ctx := context.Backgrou
    
func TestOpen(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("Can't use Unix sockets on Windows")
	}
	postgresPath, err := exec.LookPath("postgres")
	if err != nil {
		t.Skip("Can't find postgres:", err)
	}
	initdbPath, err := exec.LookPath("initdb")
	if err != nil {
		t.Skip("Can't find initdb:", err)
	}

	// Create a temporary database data directory.
	currUser, err := user.Current()
	if err != nil {
		t.Fatal(err)
	}
	dir, err := ioutil.TempDir("", "gocloud_postgres_test")
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := os.RemoveAll(dir); err != nil {
			t.Errorf("Cleaning up: %v", err)
		}
	}()
	dataDir := filepath.Join(dir, "data")
	initdbCmd := exec.Command(initdbPath, "-U", currUser.Username, "-D", dataDir)
	initdbOutput := new(bytes.Buffer)
	initdbCmd.Stdout = initdbOutput
	initdbCmd.Stderr = initdbOutput
	err = initdbCmd.Run()
	if err != nil {
		t.Log(initdbOutput)
		t.Fatal(err)
	}

	// Configure the database server to listen on a Unix socket located in the temporary directory.
	socketDir, err := filepath.Abs(filepath.Join(dir, "socket"))
	if err != nil {
		t.Fatal(err)
	}
	if err := os.Mkdir(socketDir, 0777); err != nil {
		t.Fatal(err)
	}
	confData := new(bytes.Buffer)
	fmt.Fprintf(confData, "unix_socket_directories = '%s'\n", socketDir)
	err = ioutil.WriteFile(filepath.Join(dataDir, "postgresql.conf"), confData.Bytes(), 0666)
	if err != nil {
		t.Fatal(err)
	}

	// Start the database server (and arrange for it to be stopped at test end).
	server := exec.Command(postgresPath, "-D", dataDir)
	serverOutput := new(bytes.Buffer)
	server.Stdout = serverOutput
	server.Stderr = serverOutput
	if err := server.Start(); err != nil {
		t.Fatal(err)
	}
	serverSignaled := false
	defer func() {
		if !serverSignaled {
			if err := server.Process.Kill(); err != nil {
				t.Error("Stopping server:", err)
			}
		}
		// Wait for server to exit, but ignore the expected failure error code.
		server.Wait()
		if t.Failed() {
			t.Log(serverOutput)
		}
	}()

	// Now the actual test: can we connect to the database via URL opener?
	ctx := context.Background()
	dbURL := &url.URL{
		Scheme: "blablabla", // Intentionally not "postgres" to ensure any scheme works.
		User:   url.User(currUser.Username),
		Path:   "/postgres",
		// Use the query parameter to avoid https://github.com/lib/pq/issues/796
		RawQuery: url.Values{"host": {socketDir}}.Encode(),
	}
	t.Logf("PostgreSQL URL: %s", dbURL)
	db, err := new(URLOpener).OpenPostgresURL(ctx, dbURL)
	if err != nil {
		t.Fatal(err)
	}
	// Developing a realistic query would be hard, so instead we trust that the
	// PostgreSQL library reports healthy correctly. Since there's no way to
	// synchronize the server start and the ping, we might have to ping a few
	// times before it is healthy. (The overall test runner timeout will interrupt
	// if this takes too long.)
	for {
		err := db.Ping()
		if err == nil {
			break
		}
		t.Log("Ping:", err)
		time.Sleep(100 * time.Millisecond)
	}
	if err := db.Close(); err != nil {
		t.Error("Close:", err)
	}
	server.Process.Signal(os.Interrupt)
	serverSignaled = true
}