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

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

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

```

Exclude gettimeofday() tests 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"))

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
```
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