refactor(activemeta/rule): look into source code

  test regexps until end of string instead of end of line + specs.
  use Hash::try_convert for code readability.
  fix some norm issue.

lib/active_meta/rule.rb

@@ -6,11 +6,11 @@ class Rule
     alias_method :args, :arguments
 
     def initialize(attribute, rule_name, *arguments)
-      unless /^[a-z_]+$/ =~ attribute
-        raise ArgumentError, "invalide attribute #{attribute}"
+      unless /\A[a-z_]+\z/ =~ attribute
+        raise ArgumentError, "invalid attribute #{attribute}"
       end
-      unless /^[a-z_]+$/ =~ rule_name
-        raise ArgumentError, "invalide rule_name for attribute #{attribute}"
+      unless /\A[a-z_]+\z/ =~ rule_name
+        raise ArgumentError, "invalid rule_name for attribute #{attribute}"
       end
       @attribute = attribute
       @rule_name = rule_name
@@ -22,14 +22,14 @@ def metaclass
     end
 
     def opts
-      arguments.last && arguments.last.is_a?(Hash) ? arguments.last : {}
+      Hash.try_convert(arguments.last) || {}
     end
 
     def validates_context?
       @validates_context ||= begin
-        if contexts && contexts.length > 0
-          context_classes = contexts.map{|context| ActiveMeta::Contexts.const_get(context) }
-          context_classes.all?{|ctx| ctx.valid_for_rule?(self) }
+        if contexts && !contexts.empty?
+          context_classes = contexts.map{ |context| ActiveMeta::Contexts.const_get(context) }
+          context_classes.all? { |ctx| ctx.valid_for_rule?(self) }
         else
           true
         end

spec/lib/active_meta/rule_spec.rb

@@ -12,11 +12,24 @@
   context 'instance methods' do
     context '#initialize' do
       it 'should raise an ArgumentError if passed attribute is invalid' do
-        ->{ subject.new('Foo', 't') }.should raise_error ArgumentError
+        -> { subject.new('Foo', 't') }.should raise_error ArgumentError
       end
 
-      it 'should raise an ArgumentError if passed attribute is invalid' do
-        ->{ subject.new('t', 'Foo') }.should raise_error ArgumentError
+      it 'should raise an ArgumentError if passed rule_name is invalid' do
+        -> { subject.new('t', 'Foo') }.should raise_error ArgumentError
+      end
+
+      # http://ruby-doc.org/core-2.2.1/Regexp.html#class-Regexp-label-Anchors
+      it 'should raise an ArgumentError if a multiline string is passed as attribute' do
+        arg = "i_am_valid but_not_now".gsub(' ', "\n")
+
+        -> { subject.new(arg, 't') }.should raise_error ArgumentError
+      end
+
+      it 'should raise an ArgumentError if a multiline string is passed as rule_name' do
+        arg = "i_am_valid but_not_now".gsub(' ', "\n")
+
+        -> { subject.new('t', arg) }.should raise_error ArgumentError
       end
 
       it 'should store `attribute` as @attribute' do