Add MethodDefineMacros option to Naming/PredicateName cop

Follow up for #4855 (comment).

Feature
=======

This PR also add the `MethodDefineMacros` option to check on methods
dynamically defined to `Naming/PredicateName` cop.

The target that RuboCop checks by default is `define_method`. This also
applies to end user application code. The following is config/default.yml.

```yaml
Naming/PredicateName:
  MethodDefineMacros:
    - define_method
    - define_singleton_method
```

`def_node_matcher` is also used for internal affairs of RuboCop
itself. The following is config/.rubocop.yml.

```yaml
Naming/PredicateName:
  MethodDefineMacros:
    - define_method
    - define_singleton_method
    - def_node_matcher
```

The following is the effect applied to the before master branch (995315f) .

```console
% bundle exec rake internal_investigation
Running RuboCop...
Inspecting 1010 files

(snip)

Offenses:

lib/rubocop/cop/rails/has_many_or_has_one_dependent.rb:26:26: C: Rename
has_many_or_has_one_without_options? to many_or_has_one_without_options?.
        def_node_matcher :has_many_or_has_one_without_options?, <<-PATTERN
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/rubocop/cop/rails/has_many_or_has_one_dependent.rb:30:26: C: Rename
has_many_or_has_one_with_options? to many_or_has_one_with_options?.
        def_node_matcher :has_many_or_has_one_with_options?, <<-PATTERN
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
lib/rubocop/cop/rails/has_many_or_has_one_dependent.rb:34:26: C: Rename
has_dependent? to dependent?.
        def_node_matcher :has_dependent?, <<-PATTERN
                         ^^^^^^^^^^^^^^^
lib/rubocop/cop/rails/has_many_or_has_one_dependent.rb:38:26: C: Rename
has_through? to through?.
        def_node_matcher :has_through?, <<-PATTERN
                         ^^^^^^^^^^^^^
lib/rubocop/cop/rails/not_null_column.rb:34:26: C: Rename has_default?
to default?.
        def_node_matcher :has_default?, <<-PATTERN
                         ^^^^^^^^^^^^^

1010 files inspected, 5 offenses detected
RuboCop failed!
```

.rubocop.yml

@@ -10,6 +10,13 @@ AllCops:
     - 'tmp/**/*'
   TargetRubyVersion: 2.1
 
+Naming/PredicateName:
+  # Method define macros for dynamically generated method.
+  MethodDefineMacros:
+    - define_method
+    - define_singleton_method
+    - def_node_matcher
+
 Style/FrozenStringLiteralComment:
   EnforcedStyle: always
 

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [#4663](https://github.com/bbatsov/rubocop/issues/4663): Add new `Style/CommentedKeyword` cop. ([@donjar][])
 * Add `IndentationWidth` configuration for `Layout/Tab` cop. ([@rrosenblum][])
 * [#4854](https://github.com/bbatsov/rubocop/pull/4854): Add new `Lint/RegexpAsCondition` cop. ([@pocke][])
+* [#4862](https://github.com/bbatsov/rubocop/pull/4862): Add `MethodDefineMacros` option to `Naming/PredicateName` cop. ([@koic][])
 
 ### Bug fixes
 

config/default.yml

@@ -638,6 +638,10 @@ Naming/PredicateName:
   # should still be accepted
   NameWhitelist:
     - is_a?
+  # Method define macros for dynamically generated method.
+  MethodDefineMacros:
+    - define_method
+    - define_singleton_method
   # Exclude Rspec specs because there is a strong convention to write spec
   # helpers in the form of `have_something` or `be_something`.
   Exclude:

lib/rubocop/cop/naming/predicate_name.rb

@@ -18,12 +18,33 @@ module Naming
       #   # good
       #   def value? ...
       class PredicateName < Cop
+        def_node_matcher :dynamic_method_define, <<-PATTERN
+          (send nil? #method_define_macros
+            (sym $_)
+            ...)
+        PATTERN
+
+        def on_send(node)
+          dynamic_method_define(node) do |method_name|
+            predicate_prefixes.each do |prefix|
+              next if allowed_method_name?(method_name.to_s, prefix)
+
+              add_offense(
+                node,
+                location: node.first_argument.loc.expression,
+                message: message(method_name,
+                                 expected_name(method_name.to_s, prefix))
+              )
+            end
+          end
+        end
+
         def on_def(node)
           predicate_prefixes.each do |prefix|
             method_name = node.method_name.to_s
-            next unless method_name.start_with?(prefix)
-            next if method_name == expected_name(method_name, prefix)
-            next if predicate_whitelist.include?(method_name)
+
+            next if allowed_method_name?(method_name, prefix)
+
             add_offense(
               node,
               location: :name,
@@ -35,6 +56,12 @@ def on_def(node)
 
         private
 
+        def allowed_method_name?(method_name, prefix)
+          !method_name.start_with?(prefix) ||
+            method_name == expected_name(method_name, prefix) ||
+            predicate_whitelist.include?(method_name)
+        end
+
         def expected_name(method_name, prefix)
           new_name = if prefix_blacklist.include?(prefix)
                        method_name.sub(prefix, '')
@@ -60,6 +87,10 @@ def predicate_prefixes
         def predicate_whitelist
           cop_config['NameWhitelist']
         end
+
+        def method_define_macros(macro_name)
+          cop_config['MethodDefineMacros'].include?(macro_name.to_s)
+        end
       end
     end
   end

manual/cops_naming.md

@@ -256,6 +256,7 @@ Attribute | Value
 NamePrefix | is_, has_, have_
 NamePrefixBlacklist | is_, has_, have_
 NameWhitelist | is_a?
+MethodDefineMacros | define_method, define_singleton_method
 Exclude | spec/\*\*/\*
 
 ### References

spec/rubocop/cop/naming/predicate_name_spec.rb

@@ -73,4 +73,57 @@ def is_a?
       RUBY
     end
   end
+
+  context 'with method definition macros' do
+    let(:cop_config) do
+      { 'NamePrefix' => %w[is_], 'NamePrefixBlacklist' => %w[is_],
+        'MethodDefineMacros' => %w[define_method def_node_matcher] }
+    end
+
+    it 'registers an offense when using `define_method`' do
+      expect_offense(<<-RUBY.strip_indent)
+        define_method(:is_hello) do |method_name|
+                      ^^^^^^^^^ Rename `is_hello` to `hello?`.
+          method_name == 'hello'
+        end
+      RUBY
+    end
+
+    it 'registers an offense when using an internal affair macro' do
+      expect_offense(<<-RUBY.strip_indent)
+        def_node_matcher :is_hello, <<-PATTERN
+                         ^^^^^^^^^ Rename `is_hello` to `hello?`.
+          (send
+            (send nil? :method_name) :==
+            (str 'hello'))
+        PATTERN
+      RUBY
+    end
+  end
+
+  context 'without method definition macros' do
+    let(:cop_config) do
+      { 'NamePrefix' => %w[is_], 'NamePrefixBlacklist' => %w[is_] }
+    end
+
+    it 'registers an offense when using `define_method`' do
+      expect_offense(<<-RUBY.strip_indent)
+        define_method(:is_hello) do |method_name|
+                      ^^^^^^^^^ Rename `is_hello` to `hello?`.
+          method_name == 'hello'
+        end
+      RUBY
+    end
+
+    it 'does not register any offenses when using an internal affair macro' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        def_node_matcher :is_hello, <<-PATTERN
+                         ^^^^^^^^^ Rename `is_hello` to `hello?`.
+          (send
+            (send nil? :method_name) :==
+            (str 'hello'))
+        PATTERN
+      RUBY
+    end
+  end
 end