Fixes respond_to? when raise_missing_keys is on

lib/hashr.rb

@@ -57,8 +57,12 @@ def set(path, value, stack = [])
     tokens.size == 1 ? self[path] = value : self[tokens.shift, Hashr.new].set(tokens.join('.'), value, stack)
   end
 
-  def respond_to?(*args)
-    true
+  def respond_to?(method)
+    if self.class.raise_missing_keys
+      key?(method)
+    else
+      true
+    end
   end
 
   def method_missing(name, *args, &block)

test/hashr_test.rb

@@ -89,6 +89,25 @@ def teardown
     assert_equal 'foo', hashr.foo
   end
 
+  test 'respond_to? returns true if raise_missing_keys is off' do
+    Hashr.raise_missing_keys = false
+    hashr = Hashr.new
+    assert hashr.respond_to?(:foo)
+  end
+
+  test 'respond_to? returns false for missing keys if raise_missing_keys is on' do
+    Hashr.raise_missing_keys = true
+    hashr = Hashr.new
+    assert_equal false, hashr.respond_to?(:foo)
+  end
+
+  test 'respond_to? returns true for extant keys if raise_missing_keys is on' do
+    Hashr.raise_missing_keys = true
+    hashr = Hashr.new
+    hashr[:foo] = 'bar'
+    assert hashr.respond_to?(:foo)
+  end
+
   test 'defining defaults' do
     klass = Class.new(Hashr) do
       define :foo => 'foo', :bar => { :baz => 'baz' }