diff --git a/exunit.lua b/exunit.lua
new file mode 100644
index 0000000..2c1aff0
--- /dev/null
+++ b/exunit.lua
@@ -0,0 +1,275 @@
+local _M = {}
+
+local stats = {
+  assertions  = 0,
+  passed      = 0,
+  failed      = 0,
+  errored     = 0
+}
+
+local test_cases = {}
+
+local state
+local function reset_state()
+  state = {
+    test_num = 0,
+    test_name = nil,
+    test_hadfailure = false,
+    testcase_name = nil,
+    tc_assertions = 0,
+    tc_passed = 0,
+    tc_failed = 0,
+    tc_errored = 0
+  }
+end
+reset_state()
+
+local function count_assertion()
+  state.tc_assertions = state.tc_assertions + 1
+end
+
+local function count_pass()
+  state.tc_passed = state.tc_passed + 1
+end
+
+local function count_fail()
+  state.tc_failed = state.tc_failed + 1
+end
+
+local function count_error()
+  state.tc_errored = state.tc_errored + 1
+end
+
+local function failure(func, usermsg, unitmsg, ...)
+  state.test_hadfailure = true
+  unitmsg = unitmsg:format(...)
+  local info = debug.getinfo(3, "Snl")
+  print(("  %d) Failure (%s):"):format(state.test_num, state.test_name))
+  print(("%s:%d: %s"):format(info.short_src, info.currentline, unitmsg))
+  if (usermsg) then
+    print(("%s:%d: %s"):format(info.short_src, info.currentline, usermsg))
+  end
+  print("")
+end
+
+function _M.assert(assertion, msg)
+  count_assertion()
+  if not assertion then
+    failure("assert", msg, "assertion failed")
+  end
+  return assertion
+end
+
+
+function _M.assert_equal(expected, actual, msg)
+  count_assertion()
+  if expected ~= actual then
+    failure("assert_equal", msg, "expected '%s' but was '%s'", expected, actual)
+  end
+  return actual
+end
+
+function _M.assert_true(actual, msg)
+  count_assertion()
+  local actualtype = type(actual)
+  if actualtype ~= "boolean" then
+    failure("assert_true", msg, "true expected but was a "..actualtype)
+  end
+  if actual ~= true then
+    failure("assert_true", msg, "true expected but was false")
+  end
+  return actual
+end
+
+function _M.assert_false(actual, msg)
+  count_assertion()
+  local actualtype = type(actual)
+  if actualtype ~= "boolean" then
+    failure("assert_false", msg, "false expected but was a "..actualtype)
+  end
+  if actual ~= false then
+    failure("assert_false", msg, "false expected but was true")
+  end
+  return actual
+end
+
+function _M.assert_not_equal(unexpected, actual, msg)
+  count_assertion()
+  if unexpected == actual then
+    failure("assert_not_equal", msg, "'%s' not expected but was one", unexpected)
+  end
+  return actual
+end
+
+function _M.assert_match(pattern, actual, msg)
+  count_assertion()
+  if not type(pattern) == "string" then
+    failure("assert_match", msg, "expected the pattern as a string but was '%s'", pattern)
+  end
+  if not type(actual) == "string" then
+    failure("assert_match", msg, "expected a string to match pattern '%s' but was '%s'", pattern, actual)
+  end
+  if not actual:find(pattern) then
+    failure("assert_match", msg, "expected '%s' to match pattern '%s' but doesn't", actual, pattern)
+  end
+  return actual
+end
+
+function _M.assert_not_match(pattern, actual, msg)
+  count_assertion()
+  if not type(pattern) == "string" then
+    failure("assert_not_match", msg, "expected the pattern as a string but was '%s'", pattern)
+  end
+  if not type(actual) == "string" then
+    failure( "assert_not_match", msg, "expected a string to not match pattern '%s' but was '%s'", pattern, actual)
+  end
+  if actual:find(pattern) then
+    failure("assert_not_match", msg, "expected '%s' to not match pattern '%s' but it does", actual, pattern)
+  end
+  return actual
+end
+
+function _M.assert_error(msg, func)
+  count_assertion()
+  if func == nil then
+    func, msg = msg, nil
+  end
+  local functype = type(func)
+  if functype ~= "function" then
+    failure("assert_error", msg, "expected a function as last argument but was a "..functype)
+  end
+  local ok, errmsg = pcall(func)
+  if ok then
+    failure( "assert_error", msg, "error expected but no error occurred" )
+  end
+end
+
+function _M.assert_pass(msg, func)
+  count_assertion()
+  if func == nil then
+    func, msg = msg, nil
+  end
+  local functype = type(func)
+  if functype ~= "function" then
+    failure("assert_pass", msg, "expected a function as last argument but was a %s", functype)
+  end
+  local ok, errmsg = pcall(func)
+  if not ok then
+    failure( "assert_pass", msg, "no error expected but error was: '%s'", errmsg )
+  end
+end
+
+local typenames = { "nil", "boolean", "number", "string", "table", "function", "thread", "userdata" }
+-- ex.assert_typename functions
+for _, typename in ipairs(typenames) do
+  local assert_typename = "assert_"..typename
+  _M[assert_typename] = function(actual, msg)
+    count_assertion()
+    local actualtype = type(actual)
+    if actualtype ~= typename then
+      failure(assert_typename, msg, typename.." expected but was a "..actualtype)
+    end
+    return actual
+  end
+end
+
+
+-- ex.assert_not_typename functions
+for _, typename in ipairs(typenames) do
+  local assert_not_name = "assert_not_"..typename
+  _M[assert_not_name] = function(actual, msg)
+    count_assertion()
+    if type(actual) == typename then
+      failure( assert_not_typename, msg, typename.." not expected but was one" )
+    end
+  end
+end
+
+function _M.import()
+  local env = getfenv(1)
+  for k, v in pairs(_M) do
+    if (type(k) == "string" and k:match("^assert_")) then
+      env[k] = v
+    end
+  end
+end
+
+function _M.new(name)
+  assert(name and type(name) == "string", "test case must have a name")
+  local tc = {}
+  test_cases[tc] = name
+  test_cases[#test_cases+1] = tc
+  return tc
+end
+
+local function update_stats()
+  for _, v in ipairs({"assertions", "passed", "failed", "errored"}) do
+    stats[v] = stats[v] + state["tc_"..v]
+  end
+end
+
+function _M.run(tc)
+  reset_state()
+  local function istest(k, v)
+    return type(k) == "string" and type(v) == "function" and k:match("^test_")
+  end
+
+  local count = 0
+  for k, v in pairs(tc) do
+    if istest(k, v) then
+      count = count+1
+    end
+  end
+
+  state.testcase_name = test_cases[tc]
+  print(("# Running test case '%s' (%d tests)\n"):format(test_cases[tc], count))
+  for k, v in pairs(tc) do
+    if istest(k, v) then
+      state.test_num = state.test_num + 1
+      state.test_name = k
+      do_test(v, tc.setup, tc.teardown)
+    end
+  end
+
+  print(state.tc_assertions.." assertions checked")
+  print(("Finished test case '%s'. %s tests (%d passed, %d failed, %d errored)\n"):format(state.testcase_name, count, state.tc_passed, state.tc_failed, state.tc_errored))
+  update_stats()
+end
+
+function _M.run_all()
+  print(("Loaded testsuite with %d testcases\n"):format(#test_cases))
+  for _, tc in ipairs(test_cases) do
+    _M.run(tc)
+  end
+  print("")
+end
+
+function do_test(func, setup, teardown)
+  local function docall(f)
+    if (type(f) ~= "function") then
+      return true
+    end
+
+    local succ, tb = xpcall(f, debug.traceback)
+    if not succ then
+      count_error()
+      print(("  %d) Error (%s):"):format(state.test_num, state.test_name))
+      print(tb, "\n")
+      return false
+    end
+    return true
+  end
+
+  state.test_hadfailure = false
+  if (not docall(setup)) or (not docall(func)) or not (docall(teardown)) then
+    return
+  else
+    if state.test_hadfailure then
+      count_fail()
+    else
+      count_pass()
+    end
+  end
+end
+
+return _M