Return an empty collection when where(:foo => []) is given

The previous behaviour was to return everything! This is now
consistent with ActiveRecord and avoids a needless request.

The new behaviour is not applied to has_one associations as they
currently seem to ignore the where method entirely.

lib/her/model/associations/association.rb

@@ -48,9 +48,13 @@ def fetch(opts = {})
           return @parent.attributes[@name] unless @params.any? || @parent.attributes[@name].blank?
           return @opts[:default].try(:dup) if @parent.new?
 
-          path = build_association_path -> { "#{@parent.request_path(@params)}#{@opts[:path]}" }
-          @klass.get(path, @params).tap do |result|
-            @cached_result = result unless @params.any?
+          if @params.values.include?([]) && !is_a?(HasOneAssociation)
+            Her::Collection.new
+          else
+            path = build_association_path -> { "#{@parent.request_path(@params)}#{@opts[:path]}" }
+            @klass.get(path, @params).tap do |result|
+              @cached_result = result unless @params.any?
+            end
           end
         end
 

lib/her/model/relation.rb

@@ -67,10 +67,14 @@ def kind_of?(thing)
       # @private
       def fetch
         @_fetch ||= begin
-          path = @parent.build_request_path(@parent.collection_path, @params)
-          method = @parent.method_for(:find)
-          @parent.request(@params.merge(:_method => method, :_path => path)) do |parsed_data, _|
-            @parent.new_collection(parsed_data)
+          if @params.values.include?([])
+            Her::Collection.new
+          else
+            path = @parent.build_request_path(@parent.collection_path, @params)
+            method = @parent.method_for(:find)
+            @parent.request(@params.merge(:_method => method, :_path => path)) do |parsed_data, _|
+              @parent.new_collection(parsed_data)
+            end
           end
         end
       end

spec/model/associations_spec.rb

@@ -440,6 +440,13 @@
         expect(user.organization.respond_to?(:empty?)).to be_truthy
         expect(user.organization).not_to be_empty
       end
+
+      it "returns an empty collection without fetching when [] is a parameter" do
+        Foo::Comment.should_not_receive(:request)
+        comments = user.comments.where(:foo_id => [])
+        comments.should respond_to(:length)
+        comments.size.should eql 0
+      end
     end
 
     context "without included parent data" do

spec/model/relation_spec.rb

@@ -60,6 +60,13 @@
         expect(Foo::User.create(fullname: "George Michael Bluth").id).to eq(3)
         expect(Foo::User.all.size).to eql 3
       end
+
+      it "returns an empty collection without fetching when [] is given" do
+        Foo::User.should_not_receive(:request)
+        users = Foo::User.where(:fullname => [])
+        users.should respond_to(:length)
+        users.size.should eql 0
+      end
     end
 
     context "for parent class" do