this hopefully fixes build test

Dockerfile

@@ -39,7 +39,8 @@ RUN apt-get update && apt-get install -y \
     screen \
     vim \
     wget \
-    wireless-tools
+    wireless-tools \
+    zlib1g-dev
 
 RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && locale-gen
 ENV LANG en_US.UTF-8

tests/build/Dockerfile

@@ -1,6 +1,18 @@
 FROM ubuntu:16.04
 
-RUN apt-get update && apt-get install -y gcc-arm-none-eabi libnewlib-arm-none-eabi python python-pip gcc g++ git autoconf gperf bison flex automake texinfo wget help2man gawk libtool libtool-bin ncurses-dev unzip unrar-free libexpat-dev sed bzip2
+RUN apt-get update && apt-get install -y gcc-arm-none-eabi libnewlib-arm-none-eabi python python-pip gcc g++ git autoconf gperf bison flex automake texinfo wget help2man gawk libtool libtool-bin ncurses-dev unzip unrar-free libexpat-dev sed bzip2 locales curl zlib1g-dev libffi-dev libssl-dev
+
+RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && locale-gen
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
+RUN curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash
+
+ENV PATH="/root/.pyenv/bin:/root/.pyenv/shims:${PATH}"
+RUN pyenv install 3.7.3
+RUN pyenv global 3.7.3
+RUN pyenv rehash
 
 RUN pip install pycrypto==2.6.1