diff --git a/Rakefile b/Rakefile
index 89f0c3c0..160e894e 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,6 @@
 require 'rubygems'
 require 'rake/gempackagetask'
+require 'rake/testtask'
 
 #so we can: ssh host rake -f $hudson_workspace/sigar/Rakefile
 Dir.chdir(File.dirname(__FILE__))
@@ -40,6 +41,8 @@ Rake::GemPackageTask.new(spec) do |pkg|
   pkg.gem_spec = spec
 end
 
+task :default => :test
+
 task :make_spec do
   File.open("#{GEM}.gemspec", "w") do |file|
     file.puts spec.to_ruby
@@ -54,9 +57,11 @@ end
 desc 'Build sigar extension'
 task :build do
   in_ext();
-  unless system("ruby extconf.rb")
-    STDERR.puts "Failed to configure"
-    break
+  unless File.exists? "Makefile"
+    unless system("ruby extconf.rb")
+      STDERR.puts "Failed to configure"
+      break
+    end
   end
   unless system(MAKE)
     STDERR.puts 'Failed to ' + MAKE
@@ -64,6 +69,13 @@ task :build do
   end
 end
 
+Rake::TestTask.new do |t|
+  in_ext()
+  t.pattern = 'test/*_test.rb'
+end
+
+task :test => [:build]
+
 desc 'Clean sigar extension'
 task :clean do
   in_ext()
diff --git a/bindings/ruby/test/cpu_test.rb b/bindings/ruby/test/cpu_test.rb
new file mode 100644
index 00000000..481da4ae
--- /dev/null
+++ b/bindings/ruby/test/cpu_test.rb
@@ -0,0 +1,24 @@
+$LOAD_PATH.unshift File.dirname(__FILE__)
+require 'helper'
+
+class CpuTest < Test::Unit::TestCase
+  def check_cpu(cpu)
+    assert_gt_eq_zero cpu.user, "user"
+    assert_gt_eq_zero cpu.sys, "sys"
+    assert_gt_eq_zero cpu.idle, "idle"
+    assert_gt_eq_zero cpu.wait, "wait"
+    assert_gt_eq_zero cpu.irq, "irq"
+    assert_gt_eq_zero cpu.soft_irq, "soft_irq"
+    assert_gt_eq_zero cpu.stolen, "stolen"
+    assert_gt_zero cpu.total, "total"
+  end
+
+  def test_cpu
+    sigar = Sigar.new
+    check_cpu sigar.cpu
+
+    sigar.cpu_list.each do |cpu|
+      check_cpu cpu
+    end
+  end
+end
diff --git a/bindings/ruby/test/file_system_test.rb b/bindings/ruby/test/file_system_test.rb
new file mode 100644
index 00000000..c70b1d76
--- /dev/null
+++ b/bindings/ruby/test/file_system_test.rb
@@ -0,0 +1,27 @@
+$LOAD_PATH.unshift File.dirname(__FILE__)
+require 'helper'
+
+class FileSystemTest < Test::Unit::TestCase
+
+  def test_file_system
+    sigar = Sigar.new
+    sigar.file_system_list.each do |fs|
+      assert_length fs.dev_name, "dev_name"
+      assert_length fs.dir_name, "dir_name"
+      assert_length fs.type_name, "type_name"
+      assert_length fs.sys_type_name, "sys_type_name"
+      assert fs.options.length >= 0, "options"
+
+      begin
+        usage = sigar.file_system_usage fs.dir_name
+      rescue err
+        if fs.type == Sigar::FSTYPE_LOCAL_DISK
+          raise err
+        end
+        # else ok, e.g. floppy drive on windows
+        next
+      end
+    end
+  end
+
+end
diff --git a/bindings/ruby/test/helper.rb b/bindings/ruby/test/helper.rb
new file mode 100644
index 00000000..32ff247f
--- /dev/null
+++ b/bindings/ruby/test/helper.rb
@@ -0,0 +1,41 @@
+require 'test/unit'
+require 'rbsigar'
+
+module Test::Unit::Assertions
+  def assert_gt_eq_zero(value, message)
+    message = build_message message, '<?> is not >= 0.', value
+    assert_block message do
+      value >= 0
+    end
+  end
+
+  def assert_gt_zero(value, message)
+    message = build_message message, '<?> is not > 0.', value
+    assert_block message do
+      value > 0
+    end
+  end
+
+  def assert_eq(expected, actual, message)
+    message = build_message message, '<?> != <?>.', expected, actual
+    assert_block message do
+      expected == actual
+    end
+  end
+
+  def assert_length(value, message)
+    message = build_message message, '<?>.length > 0.', value
+    assert_block message do
+      value.length > 0
+    end
+  end
+
+  def assert_any(value, message)
+    message = build_message message, '<?> is anything.', value
+    assert_block message do
+      true
+    end
+  end
+
+end
+
diff --git a/bindings/ruby/test/loadavg_test.rb b/bindings/ruby/test/loadavg_test.rb
new file mode 100644
index 00000000..b1aca4be
--- /dev/null
+++ b/bindings/ruby/test/loadavg_test.rb
@@ -0,0 +1,14 @@
+$LOAD_PATH.unshift File.dirname(__FILE__)
+require 'helper'
+
+class LoadAvgTest < Test::Unit::TestCase
+
+  def test_loadavg
+    begin
+      loadavg = Sigar.new.loadavg
+    rescue #XXX SigarNotImplemented (win32)
+      return
+    end
+    assert loadavg.length == 3
+  end
+end
diff --git a/bindings/ruby/test/mem_test.rb b/bindings/ruby/test/mem_test.rb
new file mode 100644
index 00000000..3f4e2f57
--- /dev/null
+++ b/bindings/ruby/test/mem_test.rb
@@ -0,0 +1,29 @@
+$LOAD_PATH.unshift File.dirname(__FILE__)
+require 'helper'
+
+class MemTest < Test::Unit::TestCase
+
+  def test_mem
+    sigar = Sigar.new
+    mem = sigar.mem
+    assert_gt_zero mem.total, "total"
+    assert_gt_zero mem.used, "used"
+
+    assert_gt_zero mem.used_percent, "used_percent"
+    assert mem.used_percent <= 100, "used_percent <= 100"
+
+    assert_gt_eq_zero mem.free_percent, "free_percent"
+    assert mem.free_percent < 100, "free_percent < 100"
+
+    assert_gt_zero mem.free, "free"
+
+    assert_gt_zero mem.actual_used, "actual_used"
+
+    assert_gt_zero mem.actual_free, "actual_free"
+
+    assert_gt_zero mem.ram, "ram"
+
+    assert (mem.ram % 8) == 0
+  end
+
+end
diff --git a/bindings/ruby/test/swap_test.rb b/bindings/ruby/test/swap_test.rb
new file mode 100644
index 00000000..565161c1
--- /dev/null
+++ b/bindings/ruby/test/swap_test.rb
@@ -0,0 +1,20 @@
+require 'test/unit'
+require 'rbsigar'
+
+class SwapTest < Test::Unit::TestCase
+
+  def test_swap
+    sigar = Sigar.new
+    swap = sigar.swap
+
+    assert_gt_eq_zero swap.total, "total"
+    assert_gt_eq_zero swap.used, "used"
+    assert_gt_eq_zero swap.free, "free"
+
+    assert_eq swap.total - swap.used, swap.free, "total-used==free"
+
+    assert_any swap.page_in, "page_in"
+    assert_any swap.page_out, "page_out"
+  end
+
+end
diff --git a/bindings/ruby/test/uptime_test.rb b/bindings/ruby/test/uptime_test.rb
new file mode 100644
index 00000000..501a0937
--- /dev/null
+++ b/bindings/ruby/test/uptime_test.rb
@@ -0,0 +1,10 @@
+$LOAD_PATH.unshift File.dirname(__FILE__)
+require 'helper'
+
+class UptimeTest < Test::Unit::TestCase
+
+  def test_uptime
+    uptime = Sigar.new.uptime
+    assert_gt_zero uptime.uptime, "uptime"
+  end
+end