Fix #162: New Rule: No Types

RULES.md

@@ -43,6 +43,7 @@ identified with `(since ...)` for convenience purposes.
 - [No Tabs](doc_rules/elvis_text_style/no_tabs.md)
 - [No throw](doc_rules/elvis_style/no_throw.md)
 - [No Trailing Whitespace](doc_rules/elvis_text_style/no_trailing_whitespace.md)
+- [No Types](doc_rules/elvis_style/no_types.md)
 - [Numeric Format](doc_rules/elvis_style/numeric_format.md)
 - [Operator Spaces](doc_rules/elvis_style/operator_spaces.md)
 - [State Record and Type](doc_rules/elvis_style/state_record_and_type.md)
@@ -63,10 +64,10 @@ identified with `(since ...)` for convenience purposes.
 ## Rulesets
 
 Rulesets in `elvis` are used to group individual rules together and can save a lot of duplication.
-`elvis` currently has four pre-defined rulesets, but gives you the ability to specify custom
+`elvis` currently has five pre-defined rulesets, but gives you the ability to specify custom
 rulesets in the configuration file.
 
-The four pre-defined rulesets are:
+The five pre-defined rulesets are:
 
 - `hrl_files`, for Erlang header files.
 - `erl_files`, for Erlang source files.

config/elvis-test-hrl-files.config

@@ -1,5 +1,5 @@
 [{elvis,
   [{config,
     [#{dirs => ["../../_build/test/lib/elvis_core/test/examples/"],
-       filter => "*.hrl",
+       filter => "test-*.hrl",
        ruleset => hrl_files}]}]}].

doc_rules/elvis_style/no_types.md

@@ -0,0 +1,26 @@
+# No Types
+
+(since [2.1.0](https://github.com/inaka/elvis_core/releases/tag/2.1.0))
+
+Avoid `-type` attributes.
+
+This rule is meant to be used on header files only.
+Defining types in public header files (especially those intended for inclusion via -include_lib())
+might lead to type name clashes between projects and even modules of a single big project.
+Instead, types should be defined in the modules which they correspond to
+(using `-export_type()` appropriately) and, in this way, take advantage of the namespacing offered
+by module names.
+In other words, this rule means that we will always need to use `some_mod:some_type()` unless
+we're referring to a type defined in the same module.
+
+> Works on `.beam` file? Yes, but it's not useful there. This rule is meant to be used for header files.
+
+## Options
+
+- None.
+
+## Example
+
+```erlang
+{elvis_style, no_types}
+```

src/elvis_rulesets.erl

@@ -34,7 +34,8 @@ rules(hrl_files) ->
                {elvis_style, no_dollar_space},
                {elvis_style, no_author},
                {elvis_style, no_catch_expressions},
-               {elvis_style, numeric_format}]);
+               {elvis_style, numeric_format},
+               {elvis_style, no_types}]);
 rules(erl_files) ->
     lists:map(fun({Mod, Rule}) -> {Mod, Rule, apply(Mod, default, [Rule])} end,
               [{elvis_text_style, line_length},

src/elvis_style.erl

@@ -1,7 +1,7 @@
 -module(elvis_style).
 
 -export([default/1, function_naming_convention/3, variable_naming_convention/3,
-         macro_names/3, macro_module_names/3, no_macros/3, no_block_expressions/3,
+         macro_names/3, macro_module_names/3, no_macros/3, no_types/3, no_block_expressions/3,
          operator_spaces/3, no_space/3, nesting_level/3, god_modules/3, no_if_expression/3,
          invalid_dynamic_call/3, used_ignored_variable/3, no_behavior_info/3,
          module_naming_convention/3, state_record_and_type/3, no_spec_with_records/3,
@@ -23,6 +23,7 @@
 -define(MACRO_AS_FUNCTION_NAME_MSG,
         "Don't use macros (like ~s on line ~p) as function names.").
 -define(NO_MACROS_MSG, "Unexpected macro (~p) used on line ~p.").
+-define(NO_TYPES_MSG, "Unexpected type (~p) defined on line ~p.").
 -define(NO_BLOCK_EXPRESSIONS_MSG,
         "Unexpected block expression (begin-end) used on line ~p.").
 -define(MISSING_SPACE_MSG, "Missing space to the ~s of ~p on line ~p").
@@ -167,6 +168,7 @@ default(consistent_generic_type) ->
 default(RuleWithEmptyDefault)
     when RuleWithEmptyDefault == macro_module_names;
          RuleWithEmptyDefault == no_macros;
+         RuleWithEmptyDefault == no_types;
          RuleWithEmptyDefault == no_block_expressions;
          RuleWithEmptyDefault == no_if_expression;
          RuleWithEmptyDefault == no_nested_try_catch;
@@ -321,6 +323,26 @@ no_macros(ElvisConfig, RuleTarget, RuleConfig) ->
 is_macro_node(Node) ->
     ktn_code:type(Node) =:= macro.
 
+-type no_types_config() :: #{allow => [atom()], ignore => [ignorable()]}.
+
+-spec no_types(elvis_config:config(), elvis_file:file(), no_types_config()) ->
+                  [elvis_result:item()].
+no_types(ElvisConfig, RuleTarget, RuleConfig) ->
+    TreeRootNode = get_root(ElvisConfig, RuleTarget, RuleConfig),
+    TypeNodes =
+        elvis_code:find(fun is_type_attribute/1, TreeRootNode, #{traverse => all, mode => node}),
+
+    lists:foldl(fun(TypeNode, Acc) ->
+                   Type = ktn_code:attr(name, TypeNode),
+                   {Line, _Col} = ktn_code:attr(location, TypeNode),
+                   [elvis_result:new(item, ?NO_TYPES_MSG, [Type, Line], Line) | Acc]
+                end,
+                [],
+                TypeNodes).
+
+is_type_attribute(Node) ->
+    ktn_code:type(Node) =:= type_attr.
+
 -type no_block_expressions_config() :: #{ignore => [ignorable()]}.
 
 -spec no_block_expressions(elvis_config:config(),

test/elvis_SUITE.erl

@@ -389,8 +389,8 @@ hrl_ruleset(_Config) ->
     ConfigPath = "../../config/elvis-test-hrl-files.config",
     ElvisConfig = elvis_config:from_file(ConfigPath),
     {fail,
-     [#{file := "../../_build/test/lib/elvis_core/test/examples/good.hrl", rules := []},
-      #{file := "../../_build/test/lib/elvis_core/test/examples/bad.hrl",
+     [#{file := "../../_build/test/lib/elvis_core/test/examples/test-good.hrl", rules := []},
+      #{file := "../../_build/test/lib/elvis_core/test/examples/test-bad.hrl",
         rules := [#{name := line_length}]}]} =
         elvis_core:rock(ElvisConfig),
     ok.

test/examples/fail_no_types.hrl

@@ -0,0 +1 @@
+-type bad_type() :: no | types | should | be | defined | in | header | files.

test/examples/hrl_usage.erl

@@ -1,4 +1,6 @@
 -module hrl_usage.
 
--include("good.hrl").
--include("bad.hrl").
+-include("test-good.hrl").
+-include("test-bad.hrl").
+-include("fail_no_types.hrl").
+-include("pass_no_types.hrl").

test/examples/more_hrl_usage.erl

@@ -1,4 +1,6 @@
 -module more_hrl_usage.
 
--include("good.hrl").
--include("bad.hrl").
+-include("test-good.hrl").
+-include("test-bad.hrl").
+-include("fail_no_types.hrl").
+-include("pass_no_types.hrl").

test/examples/pass_no_types.hrl

@@ -0,0 +1 @@
+-define(THIS_FILE, {has, no, types}).

test/style_SUITE.erl

@@ -24,7 +24,7 @@
          verify_atom_naming_convention/1, verify_no_throw/1, verify_no_dollar_space/1,
          verify_no_author/1, verify_no_catch_expressions/1, verify_numeric_format/1,
          verify_behaviour_spelling/1, verify_always_shortcircuit/1,
-         verify_consistent_generic_type/1]).
+         verify_consistent_generic_type/1, verify_no_types/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,
@@ -381,6 +381,14 @@ verify_no_macros(Config) ->
                               #{allow => ['ALLOWED_MACRO']},
                               PathPass).
 
+-spec verify_no_types(config()) -> any().
+verify_no_types(Config) ->
+    PathFail = "fail_no_types.hrl",
+    [#{line_num := 1}] = elvis_core_apply_rule(Config, elvis_style, no_types, #{}, PathFail),
+
+    PathPass = "pass_no_types.hrl",
+    [] = elvis_core_apply_rule(Config, elvis_style, no_types, #{}, PathPass).
+
 -spec verify_no_block_expressions(config()) -> any().
 verify_no_block_expressions(Config) ->
     Ext = proplists:get_value(test_file_ext, Config, "erl"),