Modernize the example and lint it

Author: paulo-ferraz-oliveira

.github/workflows/ci.yml

@@ -48,7 +48,9 @@ jobs:
           [[ $R == "404" ]] || exit 1
           _build/default/rel/example/bin/example stop
       - name: Format check
-        run: rebar3 format --verify
+        run: |
+          cd example
+          rebar3 format --verify
       - name: check our example
         run: |
           cd example

example/rebar.config

@@ -1,32 +1,36 @@
-%% -*- mode: erlang;erlang-indent-level: 2;indent-tabs-mode: nil -*-
-%% ex: ts=4 sw=4 ft=erlang et
+%% == Compiler and Profiles ==
 
-%% == Erlang Compiler ==
-
-%% Erlang compiler options
 {erl_opts,
- [warn_unused_vars,
-  warn_export_all,
-  warn_shadow_vars,
-  warn_unused_import,
-  warn_unused_function,
-  warn_bif_clash,
-  warn_unused_record,
-  warn_deprecated_function,
-  warn_obsolete_guard,
-  strict_validation,
-  warn_export_vars,
-  warn_exported_vars,
-  warn_untyped_record,
-  debug_info]}.
-
-%% == Dependencies ==
-
-{deps,
- [{mixer, "1.2.0", {pkg, inaka_mixer}},
-  trails]}. % checked out
-
-{project_plugins, [rebar3_lint, rebar3_hank, rebar3_format]}.
+ [warn_unused_import, warn_export_vars, warnings_as_errors, verbose, report, debug_info]}.
+
+{minimum_otp_vsn, "23"}.
+
+{alias, [{test, [compile, format, hank, lint, xref, dialyzer]}]}.
+
+%% == Dependencies and plugins ==
+
+{deps, [{mixer, "1.2.0", {pkg, inaka_mixer}}, trails]}. % checked out
+
+{project_plugins,
+ [{rebar3_hank, "~> 1.4.0"}, {rebar3_format, "~> 1.3.0"}, {rebar3_lint, "~> 3.0.1"}]}.
+
+%% == Format ==
+
+{format, [{files, ["*.config", "src/*"]}]}.
+
+%% == Hank ==
+
+{hank, [{ignore, ["_build/**", "_checkouts"]}]}.
+
+%% == Dialyzer + XRef ==
+
+{dialyzer,
+ [{warnings, [no_return, underspecs, unmatched_returns, error_handling, unknown]}]}.
+
+{xref_checks,
+ [undefined_function_calls, deprecated_function_calls, deprecated_functions]}.
+
+{xref_extra_paths, ["test/**"]}.
 
 %% == Shell (for interactive example) ==
 
@@ -38,17 +42,5 @@
  [{include_src, false},
   {extended_start_script, true},
   {release, {example, "0.1"}, [example, sasl]},
-  {sys_config, "rel/sys.config"}]}.
-
-%% == Alias ==
-
-{alias, [{test, [dialyzer, lint, hank]}]}.
-
-%% == hank ==
-
-{hank, [
-    {ignore, [
-        "_build/**",
-        "_checkouts/**"
-    ]}
-]}.
+  {sys_config, "rel/sys.config"},
+  {vm_args, "rel/vm.args"}]}.

example/rel/vm.args

@@ -0,0 +1,2 @@
+-name example@127.0.0.1
+-setcookie bogus

example/src/example.erl

@@ -29,7 +29,7 @@ stop(_State) ->
     ok = cowboy:stop_listener(example_http).
 
 % start_listeners() ->
--spec start_phase(atom(), application:start_type(), []) -> ok | {error, term()}.
+-spec start_phase(atom(), application:start_type(), []) -> ok.
 start_phase(start_trails_http, _StartType, []) ->
     {ok, Port} = application:get_env(example, http_port),
     {ok, ListenerCount} = application:get_env(example, http_listener_count),