New elvis_style rule: no_init_lists

RULES.md

@@ -61,6 +61,7 @@ identified with `(since ...)` for convenience purposes.
 - [State Record and Type](doc_rules/elvis_style/state_record_and_type.md)
 - [Used Ignored Variable](doc_rules/elvis_style/used_ignored_variable.md)
 - [Variable Naming Convention](doc_rules/elvis_style/variable_naming_convention.md)
+- [No Init Lists](doc_rules/elvis_style/no_init_lists.md)
 - [Prefer Unquoted Atoms](doc_rules/elvis_text_style/prefer_unquoted_atoms.md)
 
 ## `.gitignore` rules

doc_rules/elvis_style/no_init_lists.md

@@ -0,0 +1,17 @@
+# No Init Lists
+
+Do not use a list as the parameter for the `init/1` callback when implementing `gen_*` behaviours.
+It's semantically clearer to use a tuple or a map.
+[More info](https://erlangforums.com/t/args-in-gen-init-1/3169/5)
+
+> Works on `.beam` files? Yes!
+
+## Options
+
+- None.
+
+## Example
+
+```erlang
+{elvis_style, no_init_lists, #{}}
+```

src/elvis_rulesets.erl

@@ -96,6 +96,7 @@ rules(erl_files_strict) ->
                              max_function_length,
                              max_module_length,
                              no_call,
+                             no_init_lists,
                              no_common_caveats_call,
                              no_macros,
                              state_record_and_type]]);
@@ -118,6 +119,7 @@ rules(beam_files) ->
                no_debug_call,
                no_if_expression,
                no_import,
+               no_init_lists,
                no_match_in_condition,
                no_nested_try_catch,
                no_single_clause_case,

src/elvis_style.erl

@@ -12,7 +12,8 @@
          atom_naming_convention/3, no_throw/3, no_dollar_space/3, no_author/3, no_import/3,
          no_catch_expressions/3, no_single_clause_case/3, numeric_format/3, behaviour_spelling/3,
          always_shortcircuit/3, consistent_generic_type/3, export_used_types/3,
-         no_match_in_condition/3, param_pattern_matching/3, private_data_types/3, option/3]).
+         no_match_in_condition/3, param_pattern_matching/3, private_data_types/3, option/3,
+         no_init_lists/3]).
 
 -export_type([empty_rule_config/0]).
 -export_type([ignorable/0]).
@@ -30,6 +31,8 @@
               no_match_in_condition_config/0, behaviour_spelling_config/0,
               param_pattern_matching_config/0, private_data_type_config/0]).
 
+-define(NO_INIT_LISTS_MSG,
+        "Do not use a list as the parameter for the 'init' callback at position ~p.").
 -define(INVALID_MACRO_NAME_REGEX_MSG,
         "The macro named ~p on line ~p does not respect the format "
         "defined by the regular expression '~p'.").
@@ -144,6 +147,8 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 -spec default(Rule :: atom()) -> DefaultRuleConfig :: term().
+default(no_init_lists) ->
+    #{behaviours => [gen_server, gen_statem]};
 default(macro_names) ->
     #{regex => "^[A-Z](_?[A-Z0-9]+)*$"};
 default(operator_spaces) ->
@@ -1029,6 +1034,52 @@ atom_naming_convention(Config, Target, RuleConfig) ->
     AtomNodes = elvis_code:find(fun is_atom_node/1, Root, #{traverse => all, mode => node}),
     check_atom_names(Regex, RegexEnclosed, AtomNodes, []).
 
+-type no_init_lists_config() :: #{behaviours => [atom()]}.
+
+-spec no_init_lists(elvis_config:config(), elvis_file:file(), no_init_lists_config()) ->
+                       [elvis_result:item()].
+no_init_lists(Config, Target, RuleConfig) ->
+    Root = get_root(Config, Target, RuleConfig),
+    FunListAttributes =
+        case is_rule_behaviour(Root, RuleConfig) of
+            true ->
+                IsFunction = fun(Node) -> ktn_code:type(Node) == function end,
+                FunctionNodes = elvis_code:find(IsFunction, Root),
+                PairFun =
+                    fun(FunctionNode) ->
+                       Name = ktn_code:attr(name, FunctionNode),
+                       Location = ktn_code:attr(location, FunctionNode),
+                       [Content] = ktn_code:content(FunctionNode),
+                       Attributes = ktn_code:node_attr(pattern, Content),
+                       {Name,
+                        Location,
+                        [Attr || #{type := Type} = Attr <- Attributes, Type == cons]}
+                    end,
+                FunListAttributeInfos = lists:map(PairFun, FunctionNodes),
+                FilterFun = fun({Name, _, Args}) -> length(Args) =:= 1 andalso Name =:= init end,
+                lists:filter(FilterFun, FunListAttributeInfos);
+            false ->
+                []
+        end,
+
+    ResultFun =
+        fun({_, Location, _}) ->
+           Info = [Location],
+           Msg = ?NO_INIT_LISTS_MSG,
+           elvis_result:new(item, Msg, Info, Location)
+        end,
+    lists:map(ResultFun, FunListAttributes).
+
+is_rule_behaviour(Root, RuleConfig) ->
+    Behaviors = option(behaviours, RuleConfig, no_init_lists),
+    IsBehaviour = fun(Node) -> ktn_code:type(Node) == behaviour end,
+    case elvis_code:find(IsBehaviour, Root) of
+        [BehaviourNode] ->
+            lists:member(ktn_code:attr(value, BehaviourNode), Behaviors)
+        [] ->
+            false
+    end.
+
 -spec no_throw(elvis_config:config(), elvis_file:file(), empty_rule_config()) ->
                   [elvis_result:item()].
 no_throw(Config, Target, RuleConfig) ->

test/examples/no_init_lists_examples/fail_no_init_lists.erl

@@ -0,0 +1,15 @@
+-module(fail_no_init_lists).
+
+-behaviour(gen_server).
+
+-export([start_link/1, init/1, handle_cast/2, handle_call/3]).
+
+start_link(AParam) ->
+  gen_server:start_link(?MODULE, AParam, []).
+
+init([_AParam]) ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/fail_no_init_lists2.erl

@@ -0,0 +1,15 @@
+-module(fail_no_init_lists2).
+
+-behaviour(gen_server).
+
+-export([start_link/1, init/1, handle_cast/2, handle_call/3]).
+
+start_link(AParam) ->
+  gen_server:start_link(?MODULE, AParam, []).
+
+init(_A = [1, 2, 3]) ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/fail_no_init_lists3.erl

@@ -0,0 +1,21 @@
+-module(fail_no_init_lists3).
+
+-behaviour(gen_server).
+
+-export([start_link/1, init/1, handle_cast/2, handle_call/3]).
+
+start_link(AParam) ->
+  gen_server:start_link(?MODULE, AParam, []).
+
+init([_]) ->
+  ok;
+
+init(_A = [1, 2, 3]) ->
+  ok;
+
+init([undefined]) ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/pass_no_init_lists.erl

@@ -0,0 +1,21 @@
+-module(pass_no_init_lists).
+
+-behaviour(gen_server).
+
+-export([start_link/0, init/1, handle_cast/2, handle_call/3]).
+
+start_link() ->
+  gen_server:start_link(?MODULE, 1, []).
+
+init(1) ->
+  ok;
+
+init([undefined]) ->
+  ok;
+
+init([_]) ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/pass_no_init_lists2.erl

@@ -0,0 +1,18 @@
+-module(pass_no_init_lists2).
+
+-behaviour(gen_server).
+
+-export([start_link/0, init/1, init/2, handle_cast/2, handle_call/3]).
+
+start_link() ->
+  gen_server:start_link(?MODULE, #{a => map}, []).
+
+init(#{}) ->
+  ok.
+
+init([_], udnefined) ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/pass_no_init_lists3.erl

@@ -0,0 +1,18 @@
+-module(pass_no_init_lists3).
+
+-behaviour(gen_server).
+
+-export([start_link/0, init/0, init/1, handle_cast/2, handle_call/3]).
+
+start_link() ->
+  gen_server:start_link(?MODULE, {1, 2}, []).
+
+init({1, 2}) ->
+  ok.
+
+init() ->
+  ok.
+
+handle_cast(_, _) -> ok.
+
+handle_call(_, _, _) -> ok.

test/examples/no_init_lists_examples/pass_no_init_lists4.erl

@@ -0,0 +1,8 @@
+-module(pass_no_init_lists4).
+
+-export([start_link/1, init/1]).
+
+start_link(AParam) ->
+  gen_server:start_link(?MODULE, [AParam], []).
+
+init([_AParam]) -> ok.

test/style_SUITE.erl

@@ -25,7 +25,7 @@
          verify_always_shortcircuit/1, verify_consistent_generic_type/1, verify_no_types/1,
          verify_no_specs/1, verify_export_used_types/1, verify_consistent_variable_casing/1,
          verify_no_match_in_condition/1, verify_param_pattern_matching/1,
-         verify_private_data_types/1, verify_unquoted_atoms/1]).
+         verify_private_data_types/1, verify_unquoted_atoms/1, verify_no_init_lists/1]).
 %% -elvis attribute
 -export([verify_elvis_attr_atom_naming_convention/1, verify_elvis_attr_numeric_format/1,
          verify_elvis_attr_dont_repeat_yourself/1, verify_elvis_attr_function_naming_convention/1,
@@ -1448,6 +1448,27 @@ verify_atom_naming_convention(Config) ->
                                           FailPath)
         end.
 
+-spec verify_no_init_lists(config()) -> any().
+verify_no_init_lists(Config) ->
+    Ext = proplists:get_value(test_file_ext, Config, "erl"),
+
+    ExamplesDir = "no_init_lists_examples/",
+    FailPath = ExamplesDir ++ "fail_no_init_lists." ++ Ext,
+    % FailPath2 = ExamplesDir ++ "fail_no_init_lists2." ++ Ext,
+    % FailPath3 = ExamplesDir ++ "fail_no_init_lists3." ++ Ext,
+    [_] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, FailPath).
+
+    % [_] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, FailPath2),
+    % [_, _, _] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, FailPath3),
+    % PassPath = ExamplesDir ++ "pass_no_init_lists." ++ Ext,
+    % PassPath2 = ExamplesDir ++ "pass_no_init_lists2." ++ Ext,
+    % PassPath3 = ExamplesDir ++ "pass_no_init_lists3." ++ Ext,
+    % PassPath4 = ExamplesDir ++ "pass_no_init_lists4." ++ Ext,
+    % [] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, PassPath).
+    % [] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, PassPath2).
+    % [] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, PassPath3),
+    % [] = elvis_core_apply_rule(Config, elvis_style, no_init_lists, #{}, PassPath4).
+
 -spec verify_no_throw(config()) -> any().
 verify_no_throw(Config) ->
     _Group = proplists:get_value(group, Config, erl_files),