composer install 报错！！

Question

laravel 项目

执行命令：

ubuntu@ubuntu:/var/www/html/laravel$ composer install

报错如下：

Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for phpunit/php-code-coverage 4.0.8 -> satisfiable by phpunit/php-code-coverage[4.0.8].
    - phpunit/php-code-coverage 4.0.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
  Problem 2
    - Installation request for phpunit/phpunit 5.7.26 -> satisfiable by phpunit/phpunit[5.7.26].
    - phpunit/phpunit 5.7.26 requires ext-dom * -> the requested PHP extension dom is missing from your system.

  To enable extensions, verify that they are enabled in those .ini files:
    - /etc/php/7.0/cli/php.ini
    - /etc/php/7.0/cli/conf.d/10-mysqlnd.ini
    - /etc/php/7.0/cli/conf.d/10-opcache.ini
    - /etc/php/7.0/cli/conf.d/10-pdo.ini
    - /etc/php/7.0/cli/conf.d/20-calendar.ini
    - /etc/php/7.0/cli/conf.d/20-ctype.ini
    - /etc/php/7.0/cli/conf.d/20-curl.ini
    - /etc/php/7.0/cli/conf.d/20-exif.ini
    - /etc/php/7.0/cli/conf.d/20-fileinfo.ini
    - /etc/php/7.0/cli/conf.d/20-ftp.ini
    - /etc/php/7.0/cli/conf.d/20-gd.ini
    - /etc/php/7.0/cli/conf.d/20-gettext.ini
    - /etc/php/7.0/cli/conf.d/20-iconv.ini
    - /etc/php/7.0/cli/conf.d/20-json.ini
    - /etc/php/7.0/cli/conf.d/20-mbstring.ini
    - /etc/php/7.0/cli/conf.d/20-mcrypt.ini
    - /etc/php/7.0/cli/conf.d/20-mysqli.ini
    - /etc/php/7.0/cli/conf.d/20-pdo_mysql.ini
    - /etc/php/7.0/cli/conf.d/20-phar.ini
    - /etc/php/7.0/cli/conf.d/20-posix.ini
    - /etc/php/7.0/cli/conf.d/20-readline.ini
    - /etc/php/7.0/cli/conf.d/20-shmop.ini
    - /etc/php/7.0/cli/conf.d/20-sockets.ini
    - /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
    - /etc/php/7.0/cli/conf.d/20-sysvsem.ini
    - /etc/php/7.0/cli/conf.d/20-sysvshm.ini
    - /etc/php/7.0/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

截图：

Answer 1

报错很明显了，你缺少php的扩展dom，这个东西是用来读取xml的。
centos下面你可以yum install php-xml。
然后重启一下服务

Answer 2

你安装的 phpunit/php-code-coverage 4.0.8 和 phpunit/phpunit 5.7.26 都需要 ext-dom 这个PHP扩展。

安装下 ext-dom 并在 php.ini 里启用即可。