$ crystal spec
Error in line 1: while requiring "./spec/stream_spec.cr"

in spec/stream_spec.cr:1: while requiring "./spec_helper.cr"

require "./spec_helper.cr"
^

in spec/spec_helper.cr:1: while requiring "spec"

require "spec"
^

in /usr/share/crystal/src/spec.cr:126: instantiating 'Spec:Module#run()'

Spec.run
     ^~~

in /usr/share/crystal/src/spec/dsl.cr:172: instantiating 'Spec::RootContext.class#finish(Time::Span, Bool)'

      Spec::RootContext.finish(elapsed_time, @@aborted)
                        ^~~~~~

in /usr/share/crystal/src/spec/context.cr:54: instantiating 'Spec::RootContext#finish(Time::Span, Bool)'

      @@instance.finish(elapsed_time, aborted)
                 ^~~~~~

in /usr/share/crystal/src/spec/context.cr:58: instantiating 'Array(Spec::Formatter)#each()'

      Spec.formatters.each(&.finish)
                      ^~~~

in /usr/share/crystal/src/indexable.cr:187: instantiating 'each_index()'

    each_index do |i|
    ^~~~~~~~~~

in /usr/share/crystal/src/indexable.cr:187: instantiating 'each_index()'

    each_index do |i|
    ^~~~~~~~~~

in /usr/share/crystal/src/spec/context.cr:58: instantiating 'Array(Spec::Formatter)#each()'

      Spec.formatters.each(&.finish)
                      ^~~~

in /usr/share/crystal/src/spec/context.cr:58: instantiating 'Spec::Formatter+#finish()'

      Spec.formatters.each(&.finish)
                             ^~~~~~

in /usr/share/crystal/src/spec/tap_formatter.cr:27: instantiating 'IO+#<<(String)'

    @io << "1.." << @counter
        ^~

in /usr/share/crystal/src/io.cr:184: instantiating 'String#to_s(IO+)'

    obj.to_s self
        ^~~~

in /usr/share/crystal/src/string.cr:4202: instantiating 'IO+#write_utf8(Slice(UInt8))'

    io.write_utf8(to_slice)
       ^~~~~~~~~~

in /usr/share/crystal/src/io.cr:479: instantiating 'IO::Encoder#write(IO+, Slice(UInt8))'

      encoder.write(self, slice)
              ^~~~~

in /usr/share/crystal/src/io/encoding.cr:37: instantiating 'IO+#write(Slice(UInt8))'

        io.write(outbuf.to_slice[0, outbuf.size - outbytesleft])
           ^~~~~

in /usr/share/crystal/src/flate/writer.cr:53: instantiating 'consume_output(LibZ::Flush)'

    consume_output LibZ::Flush::NO_FLUSH
    ^~~~~~~~~~~~~~

in /usr/share/crystal/src/flate/writer.cr:89: instantiating 'loop()'

    loop do
    ^~~~

in /usr/share/crystal/src/flate/writer.cr:89: instantiating 'loop()'

    loop do
    ^~~~

in /usr/share/crystal/src/flate/writer.cr:93: instantiating 'IO+#write(Slice(UInt8))'

      @output.write(@buf.to_slice[0, @buf.size - @stream.avail_out])
              ^~~~~

in /usr/share/crystal/src/io/argf.cr:79: undefined method '<' for Nil (compile-time type is (Int32 | Nil))

    if read_count < count
                  ^

Rerun with --error-trace to show a complete error trace.