Load list of rules dynamically

spec/ameba/rule_spec.cr

@@ -1,12 +1,6 @@
 require "../../spec/spec_helper"
 
 module Ameba
-  describe RULES do
-    it "contains available rules" do
-      Ameba::RULES.empty?.should be_false
-    end
-  end
-
   describe Rule do
     describe "#catch" do
       it "accepts and returns source" do
@@ -20,5 +14,11 @@ module Ameba
         DummyRule.new.name.should eq "DummyRule"
       end
     end
+
+    describe ".rules" do
+      it "returns a list of all defined rules" do
+        Rule.rules.includes?(DummyRule).should be_true
+      end
+    end
   end
 end

src/ameba.cr

@@ -25,7 +25,7 @@ module Ameba
   end
 
   def catch(source : Source)
-    RULES.each do |rule|
+    Rule.rules.each do |rule|
       rule.new.test(source)
     end
   end

src/ameba/rule.cr

@@ -1,12 +1,4 @@
 module Ameba
-  RULES = [
-    Rules::ComparisonToBoolean,
-    Rules::LineLength,
-    Rules::TrailingBlankLines,
-    Rules::TrailingWhitespace,
-    Rules::UnlessElse,
-  ]
-
   abstract struct Rule
     abstract def test(source : Source)
 
@@ -21,5 +13,9 @@ module Ameba
     def name
       self.class.name.gsub("Ameba::Rules::", "")
     end
+
+    def self.rules
+      {{ @type.subclasses }}
+    end
   end
 end