Simple Mongo PHP Driver extension installer for Travis CI. Works like a charm for other PECL extensions too.

.travis.yml

before_script:
  - ./path/to/mongo-php-driver-installer.sh

mongo-php-driver-installer.sh

#!/bin/bash

wget http://pecl.php.net/get/mongo-1.2.10.tgz
tar -xzf mongo-1.2.10.tgz
sh -c "cd mongo-1.2.10 && phpize && ./configure && sudo make install"
echo "extension=mongo.so" >> `php --ini | grep "Loaded Configuration" | sed -e "s|.*:\s*||"`

Credits goes to @bergie for grep/sed tricks.

There's an easier way, see https://github.com/FriendsOfSymfony/FOSOAuthServerBundle/pull/88/files

Update:

mongo is the old driver which is not compatible with PHP 7, you need to use new driver mongodb.

https://stackoverflow.com/questions/38036060/pecl-mongo-requires-php-version-5-3-0-version-5-99-99-installed-versio

For php 7 there is recommended to use pecl install -f mongodb-stable

https://github.com/FriendsOfSymfony/FOSOAuthServerBundle/blob/master/.travis.yml