proc {|cmd, key, exp, got|
if exp == nil and got == nil
raise Ccp::Failed, "#{cmd.class} should write #{key} but not found"
end
TestFailed::Differ.new(exp, got, key).execute
raise Ccp::Failed, "[FATAL] %s expected %s, but got %s" % [cmd.class, exp.class, got.class]
}