rails testが実行できない

rails serverは実行できるけれど、rails testを実行しても応答がない
ctrl-cで強制終了すると、以下のようなエラーが出力された。

$ rails test
^C/Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/run.rb:117:in `gets': Interrupt
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/run.rb:117:in `verify_server_version'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/run.rb:62:in `run'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/run.rb:42:in `warm_run'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/run.rb:35:in `call'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/command.rb:7:in `call'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/rails.rb:24:in `call'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client/command.rb:7:in `call'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/client.rb:30:in `run'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/bin/spring:49:in `<top (required)>'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `load'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `<top (required)>'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
    from /Users/macbook/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
    from /Users/macbook/Git/boardgamematching/bin/spring:15:in `<top (required)>'
    from bin/rails:3:in `load'
    from bin/rails:3:in `<main>'

解決方法

springを停止する

$ spring stop
Spring stopped.

参考
railsのコマンドが動かない時はspringを(stop|kill)してみよう
http://qiita.com/yokozawa/items/7b92c260f8c3dfec8e28