convert be_an_instance_of matcher to Matcher

lib/spec/matchers/be_instance_of.rb

@@ -1,28 +1,5 @@
 module Spec
   module Matchers
-    class BeInstanceOf
-      def initialize(expected)
-        @expected = expected
-      end
-
-      def matches?(actual)
-        @actual = actual
-        @actual.instance_of?(@expected)
-      end
-
-      def description
-        "be an instance of #{@expected}"
-      end
-
-      def failure_message_for_should
-        "expected instance of #{@expected}, got #{@actual.inspect}"
-      end
-
-      def failure_message_for_should_not
-        "expected #{@actual.inspect} not to be an instance of #{@expected}"
-      end
-    end
-
     # :call-seq:
     #   should be_instance_of(expected)
     #   should be_an_instance_of(expected)
@@ -36,10 +13,14 @@ def failure_message_for_should_not
     #   5.should be_instance_of(Fixnum)
     #   5.should_not be_instance_of(Numeric)
     #   5.should_not be_instance_of(Float)
-    def be_instance_of(expected)
-      BeInstanceOf.new(expected)
+    def be_an_instance_of(expected)
+      Matcher.new :be_an_instance_of, expected do |expected|
+        match do |actual|
+          actual.instance_of?(expected)
+        end
+      end
     end
 
-    alias_method :be_an_instance_of, :be_instance_of
+    alias_method :be_instance_of, :be_an_instance_of
   end
 end

spec/spec/matchers/be_instance_of_spec.rb

@@ -2,22 +2,24 @@
 
 module Spec
   module Matchers
-    [:be_instance_of, :be_an_instance_of].each do |method|
+    [:be_an_instance_of, :be_instance_of].each do |method|
       describe "actual.should #{method}(expected)" do
         it "passes if actual is instance of expected class" do
           5.should send(method, Fixnum)
         end
 
         it "fails if actual is instance of subclass of expected class" do
-          lambda { 5.should send(method, Numeric) }.should fail_with(%Q{expected instance of Numeric, got 5})
+          lambda { 5.should send(method, Numeric) }.should fail_with(%Q{expected 5 to be an instance of Numeric})
         end
 
         it "fails with failure message for should unless actual is instance of expected class" do
-          lambda { "foo".should send(method, Array) }.should fail_with(%Q{expected instance of Array, got "foo"})
+          lambda { "foo".should send(method, Array) }.should fail_with(%Q{expected "foo" to be an instance of Array})
         end
 
         it "provides a description" do
-          Spec::Matchers::BeInstanceOf.new(Class).description.should == "be an instance of Class"
+          matcher = be_an_instance_of(Fixnum)
+          matcher.matches?(Numeric)
+          matcher.description.should == "be an instance of Fixnum"
         end
       end