Elixir unit tests

Running Elixir unit tests

You can run Elixir unit tests with command:

make quicktest

You need to have ejabberd compile with Elixir and tools enabled.

To help with troubleshooting Elixir tests, we have added a special macro in ejabberd logger.hrl include file: ?EXUNIT_LOG

To use this, in test file:

in `setup_all, add:
```
Application.start(:logger)
```
Enable log capture for the test you want to analyse by adding capture_log tag before test implementation:
```
@tag capture_log: true
```

In the ejabberd code, if logger.hrl is included, you can code adds a EXUNIT_LOG macro:

?EXUNIT_LOG("My debug log:~p ~p", [Arg1, Arg2])