title: function is undefined in elixir (mix test)
body: <p>I'm trying to install <a href="https://github.com/pprzetacznik/IElixir" rel="nofollow noreferrer">IElixir</a> Jupyter notebook kernel on Xubuntu 16.04. I've successfully done it before on another machine with Xubuntu 16.04.</p>
  
  <p>I have the latest erlang otp 19.3 and elixir 1.4.4 (installed using kiex).</p>
  
  <p>After executing <code>mix test</code> i get an error about undefined <code>:erlzmq_nif.context/1</code> function:</p>
  
  <pre><code>** (Mix) Could not start application ielixir: exited in: IElixir.start(:normal, [])
      ** (EXIT) an exception was raised:
          ** (UndefinedFunctionError) function :erlzmq_nif.context/1 is undefined (module :erlzmq_nif is not available)
              :erlzmq_nif.context(1)
              (ielixir) lib/ielixir.ex:13: IElixir.start/2
              (kernel) application_master.erl:273: :application_master.start_it_old/4
  </code></pre>
  
  <p>The thing is all the dependencies are succesfully installed and I am able to use <code>:erlzmq_nif.context/1</code> in <code>iex</code>:</p>
  
  <pre><code>iex(1)&gt; :erlzmq_nif.context 1
  {:ok, ""}
  iex(2)&gt; 
  </code></pre>
  
  <p>I've copied my build of <code>erlzmq</code> to <code>/usr/lib/erlang/lib</code> so that I can use it in erlang too:</p>
  
  <pre><code>1&gt; erlzmq_nif:context(3).
  {ok,&lt;&lt;&gt;&gt;}
  2&gt; 
  </code></pre>
  
  <p>Why is this lib not visible to elixir when using mix?</p>