Content type validation macro to matcher conversion

shoulda_macros/matchers.rb

 require 'shoulda_macros/matchers/have_attached_file_matcher'
 require 'shoulda_macros/matchers/validate_attachment_presence_matcher'
+require 'shoulda_macros/matchers/validate_attachment_content_type_matcher'

shoulda_macros/matchers/validate_attachment_content_type_matcher.rb

+module Paperclip
+  module Shoulda
+    module Matchers
+      def validate_attachment_content_type name
+        ValidateAttachmentContentTypeMatcher.new(name)
+      end
+
+      class ValidateAttachmentContentTypeMatcher
+        def initialize attachment_name
+          @attachment_name = attachment_name
+        end
+
+        def allowing *types
+          @allowed_types = types.flatten
+          self
+        end
+
+        def rejecting *types
+          @rejected_types = types.flatten
+          self
+        end
+
+        def matches? subject
+          @subject = subject
+          @allowed_types && @rejected_types &&
+          allowed_types_allowed? && rejected_types_rejected?
+        end
+
+        def failure_message
+          "Content types #{@allowed_types.join(", ")} should be accepted" +
+          " and #{@rejected_types.join(", ")} rejected by #{@attachment_name}"
+        end
+
+        def negative_failure_message
+          "Content types #{@allowed_types.join(", ")} should be rejected" + 
+          " and #{@rejected_types.join(", ")} accepted by #{@attachment_name}"
+        end
+
+        def description
+          "validate the content types allowed on attachment #{@attachment_name}"
+        end
+
+        protected
+
+        def allow_types?(types)
+          types.all? do |type|
+            file = StringIO.new(".")
+            file.content_type = type
+            attachment = @subject.new.attachment_for(@attachment_name)
+            attachment.assign(file)
+            attachment.errors[:content_type].nil?
+          end
+        end
+
+        def allowed_types_allowed?
+          allow_types?(@allowed_types)
+        end
+
+        def rejected_types_rejected?
+          not allow_types?(@rejected_types)
+        end
+      end
+    end
+  end
+end
+

test/matchers/validate_attachment_content_type_matcher_test.rb

+require 'test/helper'
+
+class ValidateAttachmentContentTypeMatcherTest < Test::Unit::TestCase
+  context "validate_attachment_content_type" do
+    setup do
+      reset_table("dummies") do |d|
+        d.string :avatar_file_name
+      end
+      @dummy_class = reset_class "Dummy"
+      @dummy_class.has_attached_file :avatar
+      @matcher     = validate_attachment_content_type(:avatar).
+                       allowing(%w(image/png image/jpeg)).
+                       rejecting(%w(audio/mp3 application/octet-stream))
+    end
+
+    should "reject a class with no validation" do
+      assert_rejects @matcher, @dummy_class
+    end
+
+    should "reject a class with a validation that doesn't match" do
+      @dummy_class.validates_attachment_content_type :avatar, :content_type => %r{audio/.*}
+      assert_rejects @matcher, @dummy_class
+    end
+
+    should "accept a class with a validation" do
+      @dummy_class.validates_attachment_content_type :avatar, :content_type => %r{image/.*}
+      assert_accepts @matcher, @dummy_class
+    end
+  end
+end