Improve test coverage

Renames test/test_packbeam.erl -> test/packbeam_api_tests.erl to conform to standard eunit naming
conventions, with the test module having the same name as the module is test with `_tests` appended
to the name. This allows testing individual modules with `rebar3 eunit -m MODULE`.

Add packbeam_tests.erl to test the main `packbeam` cli escript. The escript should be assembled in
the `test` profile, as is done in the Makefile `etest` target, before eunit tests are run.

Signed-off-by: Winford <winford@object.stream>

Author: UncleGrumpy

Makefile

@@ -16,6 +16,7 @@ doc:
 	rebar3 as doc ex_doc
 
 etest:
+	rebar3 as test escriptize
 	rebar3 as test eunit --cover
 	rebar3 as test proper --cover
 	rebar3 as test cover --verbose

rebar.config

@@ -32,7 +32,9 @@
 {profiles, [
     {test, [
         {erl_opts, [debug_info]},
+        {extra_src_dirs, ["test"]},
         {cover_enabled, true},
+        {cover_opts, [{verbose, true}]},
         {deps, [
             {proper, "1.4.0"}
         ]},

test/test_packbeam.erl test/packbeam_api_tests.erltest/test_packbeam.erl renamed to test/packbeam_api_tests.erl

@@ -16,7 +16,7 @@
 %%
 %% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
 
--module(test_packbeam).
+-module(packbeam_api_tests).
 
 -include_lib("proper/include/proper.hrl").
 -include_lib("eunit/include/eunit.hrl").