Use NodeVisitor by default and remove the boilerplace code

src/ameba/rule/base.cr

@@ -32,7 +32,12 @@ module Ameba::Rule
 
     # This method is designed to test the source passed in. If source has issues
     # that are tested by this rule, it should add an issue.
-    abstract def test(source : Source)
+    #
+    # Be default it uses a node visitor to traverse all the nodes in the source.
+    # Must be overriten for other type of rules.
+    def test(source : Source)
+      AST::NodeVisitor.new self, source
+    end
 
     def test(source : Source, node : Crystal::ASTNode, *opts)
       # can't be abstract

src/ameba/rule/lint/comparison_to_boolean.cr

@@ -28,10 +28,6 @@ module Ameba::Rule::Lint
 
     MSG = "Comparison to a boolean is pointless"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       comparison = %w(== != ===).includes?(node.name)
       to_boolean = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||

src/ameba/rule/lint/debugger_statement.cr

@@ -18,10 +18,6 @@ module Ameba::Rule::Lint
 
     MSG = "Possible forgotten debugger statement detected"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       return unless node.name == "debugger" &&
                     node.args.empty? &&

src/ameba/rule/lint/empty_ensure.cr

@@ -46,10 +46,6 @@ module Ameba::Rule::Lint
 
     MSG = "Empty `ensure` block detected"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::ExceptionHandler)
       node_ensure = node.ensure
       return if node_ensure.nil? || !node_ensure.nop?

src/ameba/rule/lint/empty_expression.cr

@@ -38,10 +38,6 @@ module Ameba::Rule::Lint
     MSG      = "Avoid empty expression %s"
     MSG_EXRS = "Avoid empty expressions"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::NilLiteral)
       exp = node_source(node, source.lines).try &.join
 

src/ameba/rule/lint/hash_duplicated_key.cr

@@ -27,10 +27,6 @@ module Ameba::Rule::Lint
 
     MSG = "Duplicated keys in hash literal: %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::HashLiteral)
       return unless (keys = duplicated_keys(node.entries)).any?
 

src/ameba/rule/lint/literal_in_condition.cr

@@ -30,10 +30,6 @@ module Ameba::Rule::Lint
 
     MSG = "Literal value found in conditional"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def check_node(source, node)
       return unless literal?(node.cond)
       issue_for node, MSG

src/ameba/rule/lint/literal_in_interpolation.cr

@@ -25,10 +25,6 @@ module Ameba::Rule::Lint
 
     MSG = "Literal value found in interpolation"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::StringInterpolation)
       found = node.expressions.any? { |e| !e.is_a?(Crystal::StringLiteral) && literal?(e) }
       return unless found

src/ameba/rule/lint/rand_zero.cr

@@ -30,10 +30,6 @@ module Ameba::Rule::Lint
 
     MSG = "%s always returns 0"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       return unless node.name == "rand" &&
                     node.args.size == 1 &&

src/ameba/rule/lint/redundant_with_index.cr

@@ -32,10 +32,6 @@ module Ameba::Rule::Lint
       description "Disallows redundant `with_index` calls"
     end
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       args, block = node.args, node.block
 

src/ameba/rule/lint/redundant_with_object.cr

@@ -33,10 +33,6 @@ module Ameba::Rule::Lint
       description "Disallows redundant `with_object` calls"
     end
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       return if node.name != "each_with_object" ||
                 node.args.size != 1 ||

src/ameba/rule/lint/shadowed_exception.cr

@@ -41,10 +41,6 @@ module Ameba::Rule::Lint
 
     MSG = "Exception handler has shadowed exceptions: %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::ExceptionHandler)
       return unless excs = node.rescues
 

src/ameba/rule/lint/useless_condition_in_when.cr

@@ -51,10 +51,6 @@ module Ameba::Rule::Lint
       issue_for cond, MSG
     end
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::When)
       ConditionInWhenVisitor.new self, source, node
     end

src/ameba/rule/metrics/cyclomatic_complexity.cr

@@ -17,10 +17,6 @@ module Ameba::Rule::Metrics
 
     MSG = "Cyclomatic complexity too high [%d/%d]"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Def)
       complexity = AST::CountingVisitor.new(node).count
 

src/ameba/rule/performance/any_after_filter.cr

@@ -34,10 +34,6 @@ module Ameba::Rule::Performance
       description "Identifies usage of `any?` calls that follow filters."
     end
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Call)
       return unless node.name == ANY_NAME && (obj = node.obj)
 

src/ameba/rule/style/constant_names.cr

@@ -29,10 +29,6 @@ module Ameba::Rule::Style
 
     MSG = "Constant name should be screaming-cased: %s, not %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Assign)
       if (target = node.target).is_a? Crystal::Path
         name = target.names.first

src/ameba/rule/style/method_names.cr

@@ -45,10 +45,6 @@ module Ameba::Rule::Style
 
     MSG = "Method name should be underscore-cased: %s, not %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Def)
       return if (expected = node.name.underscore) == node.name
 

src/ameba/rule/style/negated_conditions_in_unless.cr

@@ -34,10 +34,6 @@ module Ameba::Rule::Style
 
     MSG = "Avoid negated conditions in unless blocks"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Unless)
       return unless negated_condition? node.cond
       issue_for node, MSG

src/ameba/rule/style/predicate_name.cr

@@ -37,10 +37,6 @@ module Ameba::Rule::Style
 
     MSG = "Favour method name '%s?' over '%s'"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Def)
       if node.name =~ /^(is|has)_(\w+)\?/
         alternative = $2

src/ameba/rule/style/redundant_begin.cr

@@ -64,10 +64,6 @@ module Ameba::Rule::Style
 
     MSG = "Redundant `begin` block detected"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Def)
       return unless redundant_begin?(source, node)
 

src/ameba/rule/style/redundant_next.cr

@@ -105,10 +105,6 @@ module Ameba::Rule::Style
 
     MSG = "Redundant `next` detected"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Block)
       AST::RedundantControlExpressionVisitor.new(self, source, node.body)
     end

src/ameba/rule/style/redundant_return.cr

@@ -102,10 +102,6 @@ module Ameba::Rule::Style
 
     MSG = "Redundant `return` detected"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Def)
       AST::RedundantControlExpressionVisitor.new(self, source, node.body)
     end

src/ameba/rule/style/type_names.cr

@@ -59,10 +59,6 @@ module Ameba::Rule::Style
 
     MSG = "Type name should be camelcased: %s, but it was %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     private def check_node(source, node)
       name = node.name.to_s
       expected = name.camelcase

src/ameba/rule/style/unless_else.cr

@@ -50,10 +50,6 @@ module Ameba::Rule::Style
 
     MSG = "Favour if over unless with else"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::Unless)
       return if node.else.nop?
       issue_for node, MSG

src/ameba/rule/style/variable_names.cr

@@ -30,10 +30,6 @@ module Ameba::Rule::Style
 
     MSG = "Var name should be underscore-cased: %s, not %s"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     private def check_node(source, node)
       return if (expected = node.name.underscore) == node.name
 

src/ameba/rule/style/while_true.cr

@@ -33,10 +33,6 @@ module Ameba::Rule::Style
 
     MSG = "While statement using true literal as condition"
 
-    def test(source)
-      AST::NodeVisitor.new self, source
-    end
-
     def test(source, node : Crystal::While)
       return unless node.cond.true_literal?
       issue_for node, MSG