Add locales

tests/Dockerfile

@@ -12,4 +12,12 @@ RUN apt-get update && apt-get install --yes --no-install-recommends git wget
 #
 #RUN echo "xdebug.mode = debug" >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini
 
+RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y locales
+
+RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && \
+    dpkg-reconfigure --frontend=noninteractive locales && \
+    update-locale LANG=en_US.UTF-8
+
+ENV LANG en_US.UTF-8
+
 RUN wget https://raw.githubusercontent.com/composer/getcomposer.org/76a7060ccb93902cd7576b67264ad91c8a2700e2/web/installer -O - -q | php -- --quiet --install-dir=/usr/local/bin --filename=composer