[#69] [#70] Fix bugs related to regex cope

Rewrite regex cop code to find regexes usings and then filter already
defined constants.
Additionally added rescue for regex samples with illegal syntax

DOCUMENTATION.md

@@ -987,6 +987,14 @@ puts "hi" if name =~ /john/
 
 ```
 
+![](https://placehold.it/10/f03c15/000000?text=+) raises if somewhere in code used regex but defined another const
+```ruby
+
+ANOTHER_CONST = /ivan/
+puts "hi" if name =~ /john/
+
+```
+
 ![](https://placehold.it/10/2cbe4e/000000?text=+) ignores matching constants
 ```ruby
 
@@ -996,6 +1004,14 @@ puts "hi" if name =~ REGEX
 
 ```
 
+![](https://placehold.it/10/2cbe4e/000000?text=+) ignores freeze calling
+```ruby
+
+REGEX = /john/.freeze
+puts "hi" if name =~ REGEX
+
+```
+
 ![](https://placehold.it/10/2cbe4e/000000?text=+) ignores named ruby constants
 ```ruby
 
@@ -1010,6 +1026,14 @@ puts "hi" if name =~ /[[:alpha:]]/
 name = "john"
 puts "hi" if name =~ /.{#{name.length}}/
 
+```
+
+![](https://placehold.it/10/2cbe4e/000000?text=+) rescue dynamic regexes dynamic regexs
+```ruby
+
+name = "john"
+puts "hi" if name =~ /foo(?=bar)/
+
 ```
 ## Ducalis::RestOnlyCop
 

lib/ducalis/cops/regex_cop.rb

@@ -5,6 +5,8 @@
 
 module Ducalis
   class RegexCop < RuboCop::Cop::Cop
+    include RuboCop::Cop::DefNode
+
     OFFENSE = <<-MESSAGE.gsub(/^ +\|\s/, '').strip
       | It's better to move regex to constants with example instead of direct using it. It will allow you to reuse this regex and provide instructions for others.
 
@@ -34,22 +36,47 @@ class RegexCop < RuboCop::Cop::Cop
     DETAILS = "Available regexes are:
       #{SELF_DESCRIPTIVE.map { |name| "`#{name}`" }.join(', ')}"
 
-    def on_regexp(node)
-      return if node.parent.type == :casgn
-      return if SELF_DESCRIPTIVE.include?(node.source)
-      return if node.child_nodes.any? { |child_node| child_node.type == :begin }
-      add_offense(node, :expression, format(OFFENSE, present_node(node)))
+    DEFAULT_EXAMPLE = 'some_example'
+
+    def on_begin(node)
+      not_defined_regexes(node).each do |regex|
+        next if SELF_DESCRIPTIVE.include?(regex.source) || const_dynamic?(regex)
+        add_offense(regex, :expression, format(OFFENSE, present_node(regex)))
+      end
     end
 
     private
 
+    def_node_search :const_using, '(regexp $_ ... (regopt))'
+    def_node_search :const_definition, '(casgn ...)'
+
+    def not_defined_regexes(node)
+      const_using(node).reject do |regex|
+        defined_as_const?(regex, const_definition(node))
+      end.map(&:parent)
+    end
+
+    def defined_as_const?(regex, definitions)
+      definitions.any? { |node| const_using(node).any? { |use| use == regex } }
+    end
+
+    def const_dynamic?(node)
+      node.child_nodes.any?(&:begin_type?)
+    end
+
     def present_node(node)
       {
         constant: node.source,
         fixed_string: node.source_range.source_line
                           .sub(node.source, 'CONST_NAME').lstrip,
-        example: Regexp.new(node.to_a.first.to_a.first).examples.sample
+        example: regex_sample(node)
       }
     end
+
+    def regex_sample(node)
+      Regexp.new(node.to_a.first.to_a.first).examples.sample
+    rescue RegexpExamples::IllegalSyntaxError
+      DEFAULT_EXAMPLE
+    end
   end
 end

spec/ducalis/cops/regex_cop_spec.rb

@@ -16,6 +16,14 @@
     expect(cop).to raise_violation(/puts "hi" if name =~ CONST_NAME/)
   end
 
+  it 'raises if somewhere in code used regex but defined another const' do
+    inspect_source(cop, [
+                     'ANOTHER_CONST = /ivan/',
+                     'puts "hi" if name =~ /john/'
+                   ])
+    expect(cop).to raise_violation(/puts "hi"/)
+  end
+
   it 'ignores matching constants' do
     inspect_source(cop, [
                      'REGEX = /john/',
@@ -25,6 +33,14 @@
     expect(cop).to_not raise_violation
   end
 
+  it 'ignores freeze calling' do
+    inspect_source(cop, [
+                     'REGEX = /john/.freeze',
+                     'puts "hi" if name =~ REGEX'
+                   ])
+    expect(cop).to_not raise_violation
+  end
+
   it 'ignores named ruby constants' do
     inspect_source(cop, [
                      'name = "john"',
@@ -40,4 +56,14 @@
                    ])
     expect(cop).to_not raise_violation
   end
+
+  it 'rescue dynamic regexes dynamic regexs' do
+    inspect_source(cop, [
+                     'name = "john"',
+                     'puts "hi" if name =~ /foo(?=bar)/'
+                   ])
+    expect(cop).to raise_violation(
+      %r{CONST_NAME = /foo\(\?=bar\)/ # "some_example"}
+    )
+  end
 end