Fixed type checking in WebMock::Response#assert_valid_body! to correc…

…tly identify Hash objects and improved error message.

lib/webmock/response.rb

@@ -117,11 +117,11 @@ def assert_valid_body!
       return if @body.nil?
       return if valid_types.any? { |c| @body.is_a?(c) }
 
-      if @body.class.is_a?(Hash)
-        raise InvalidBody, "must be one of: #{valid_types}, but you've used a #{@body.class}' instead." \
-          "\n What shall we encode it to? try calling .to_json .to_xml instead on the hash instead, or otherwise convert it to a string."
+      if @body.is_a?(Hash)
+        raise InvalidBody, "must be one of: #{valid_types}, but you've used a #{@body.class}. " \
+          "Please convert it by calling .to_json .to_xml, or otherwise convert it to a string."
       else
-        raise InvalidBody, "must be one of: #{valid_types}. '#{@body.class}' given"
+        raise InvalidBody, "must be one of: #{valid_types}. '#{@body.class}' given."
       end
     end
 

spec/unit/response_spec.rb

@@ -140,12 +140,16 @@
     #
     it "should error if given a non-allowed type: a hash" do
       expect { WebMock::Response.new(body: Hash.new) }.to \
-        raise_error(WebMock::Response::InvalidBody)
+        raise_error(
+          WebMock::Response::InvalidBody,
+          "must be one of: [Proc, IO, Pathname, String, Array], but you've used a Hash. Please convert it by calling .to_json .to_xml, or otherwise convert it to a string."
+        )
     end
 
     it "should error if given a non-allowed type: something that is not a hash" do
       expect { WebMock::Response.new(body: 123) }.to \
-        raise_error(WebMock::Response::InvalidBody)
+        raise_error(WebMock::Response::InvalidBody,
+          "must be one of: [Proc, IO, Pathname, String, Array]. 'Integer' given.")
     end
   end