Updated test cases to cover bad filters and empty()
Updated test cases to cover bad filters and empty()

pecigonzalo/packer,ricardclau/packer,grubernaut/packer,ricardclau/packer,paulmey/packer,rnaveiras/packer,timsutton/packer,mitchellh/packer,hashicorp/packer,tb3088/packer,pecigonzalo/packer,timsutton/packer,grubernaut/packer,mkuzmin/packer,mitchellh/packer,grubernaut/packer,tas50/packer,dave2/packer,tb3088/packer,tas50/packer,tas50/packer,hashicorp/packer,timsutton/packer,bryson/packer,timsutton/packer,mkuzmin/packer,rnaveiras/packer,timsutton/packer,bryson/packer,bryson/packer,tb3088/packer,dave2/packer,rnaveiras/packer,mitchellh/packer,paulmey/packer,tb3088/packer,dave2/packer,rnaveiras/packer,mkuzmin/packer,paulmey/packer,youhong316/packer,youhong316/packer,youhong316/packer,tb3088/packer,grubernaut/packer,ricardclau/packer,ricardclau/packer,paulmey/packer,pecigonzalo/packer,grubernaut/packer,mitchellh/packer,ricardclau/packer,bryson/packer,youhong316/packer,dave2/packer,mkuzmin/packer,tas50/packer,pecigonzalo/packer,tas50/packer,youhong316/packer,grubernaut/packer,rnaveiras/packer,bryson/packer,rnaveiras/packer,mkuzmin/packer,tb3088/packer,ricardclau/packer,youhong316/packer,mkuzmin/packer,bryson/packer,dave2/packer,timsutton/packer,tas50/packer,mitchellh/packer,dave2/packer,paulmey/packer,paulmey/packer,hashicorp/packer,hashicorp/packer