```ruby
#
# This file is part of ruby-ffi.
# For licensing, see LICENSE.SPECS
#

require File.expand_path(File.join(File.dirname(__FILE__), "spec_helper"))

module RbxAttachFunctionSpecs
  unless FFI::Platform.windows?
    class Timeval < FFI::Struct
      layout :tv_sec, :ulong, 0, :tv_usec, :ulong, 4
    end

    module LibC
      extend FFI::Library
      ffi_lib FFI::Library::LIBC

      attach_function :gettimeofday, [:pointer, :pointer], :int
    end

    describe FFI::Library, "#attach_function" do
      it "correctly returns a value for gettimeofday" do
        t = Timeval.new
        time = LibC.gettimeofday(t.pointer, nil)
        expect(time).to be_kind_of(Integer)
      end

      it "correctly populates a struct for gettimeofday" do
        t = Timeval.new
        LibC.gettimeofday(t.pointer, nil)
        expect(t[:tv_sec]).to be_kind_of(Numeric)
        expect(t[:tv_usec]).to be_kind_of(Numeric)
      end
    end
  end
end
```

Enable gettimeofday based spec on Windows
user
```ruby
#
# This file is part of ruby-ffi.
# For licensing, see LICENSE.SPECS
#

require File.expand_path(File.join(File.dirname(__FILE__), "spec_helper"))

module RbxAttachFunctionSpecs
  class Timeval < FFI::Struct
    layout :tv_sec, :ulong, 0, :tv_usec, :ulong, 4
  end

  module LibC
    extend FFI::Library
    if FFI::Platform.windows?
      ffi_lib RbConfig::CONFIG["LIBRUBY_SO"]
    else
      ffi_lib FFI::Library::LIBC
    end

    attach_function :gettimeofday, [:pointer, :pointer], :int
  end

  describe FFI::Library, "#attach_function" do
    it "correctly returns a value for gettimeofday" do
      t = Timeval.new
      time = LibC.gettimeofday(t.pointer, nil)
      expect(time).to be_kind_of(Integer)
    end

    it "correctly populates a struct for gettimeofday" do
      t = Timeval.new
      LibC.gettimeofday(t.pointer, nil)
      expect(t[:tv_sec]).to be_kind_of(Numeric)
      expect(t[:tv_usec]).to be_kind_of(Numeric)
    end
  end
end
```
assistant