Add upstream tests

* Only add tests/*.lua for now

Signed-off-by: David Seifert <soap@gentoo.org>

1 files changed, 805 insertions, 0 deletions

diff --git a/tests/nextvar.lua b/tests/nextvar.lua
new file mode 100644
index 0000000..9e23e57
--- /dev/null
+++ b/tests/nextvar.lua
@@ -0,0 +1,805 @@
+-- $Id: testes/nextvar.lua $
+-- See Copyright Notice in file all.lua
+
+print('testing tables, next, and for')
+
+local function checkerror (msg, f, ...)
+  local s, err = pcall(f, ...)
+  assert(not s and string.find(err, msg))
+end
+
+
+local a = {}
+
+-- make sure table has lots of space in hash part
+for i=1,100 do a[i.."+"] = true end
+for i=1,100 do a[i.."+"] = undef end
+-- fill hash part with numeric indices testing size operator
+for i=1,100 do
+  a[i] = true
+  assert(#a == i)
+end
+
+-- testing ipairs
+local x = 0
+for k,v in ipairs{10,20,30;x=12} do
+  x = x + 1
+  assert(k == x and v == x * 10)
+end
+
+for _ in ipairs{x=12, y=24} do assert(nil) end
+
+-- test for 'false' x ipair
+x = false
+local i = 0
+for k,v in ipairs{true,false,true,false} do
+  i = i + 1
+  x = not x
+  assert(x == v)
+end
+assert(i == 4)
+
+-- iterator function is always the same
+assert(type(ipairs{}) == 'function' and ipairs{} == ipairs{})
+
+
+do   -- overflow (must wrap-around)
+  local f = ipairs{}
+  local k, v = f({[math.mininteger] = 10}, math.maxinteger)
+  assert(k == math.mininteger and v == 10)
+  k, v = f({[math.mininteger] = 10}, k)
+  assert(k == nil)
+end
+
+if not T then
+  (Message or print)
+    ('\n >>> testC not active: skipping tests for table sizes <<<\n')
+else --[
+-- testing table sizes
+
+
+local function mp2 (n)   -- minimum power of 2 >= n
+  local mp = 2^math.ceil(math.log(n, 2))
+  assert(n == 0 or (mp/2 < n and n <= mp))
+  return mp
+end
+
+
+local function check (t, na, nh)
+  local a, h = T.querytab(t)
+  if a ~= na or h ~= nh then
+    print(na, nh, a, h)
+    assert(nil)
+  end
+end
+
+
+-- testing C library sizes
+do
+  local s = 0
+  for _ in pairs(math) do s = s + 1 end
+  check(math, 0, mp2(s))
+end
+
+
+-- testing constructor sizes
+local sizes = {0, 1, 2, 3, 4, 5, 7, 8, 9, 15, 16, 17,
+  30, 31, 32, 33, 34, 254, 255, 256, 500, 1000}
+
+for _, sa in ipairs(sizes) do    -- 'sa' is size of the array part
+  local arr = {"return {"}
+  for i = 1, sa do arr[1 + i] = "1," end    -- build array part
+  for _, sh in ipairs(sizes) do    -- 'sh' is size of the hash part
+    for j = 1, sh do   -- build hash part
+      arr[1 + sa + j] = string.format('k%x=%d,', j, j)
+    end
+    arr[1 + sa + sh + 1] = "}"
+    local prog = table.concat(arr)
+    local f = assert(load(prog))
+    collectgarbage("stop")
+    f()    -- call once to ensure stack space
+    -- make sure table is not resized after being created
+    if sa == 0 or sh == 0 then
+      T.alloccount(2);  -- header + array or hash part
+    else
+      T.alloccount(3);  -- header + array part + hash part
+    end
+    local t = f()
+    T.alloccount();
+    collectgarbage("restart")
+    assert(#t == sa)
+    check(t, sa, mp2(sh))
+  end
+end
+
+
+-- tests with unknown number of elements
+local a = {}
+for i=1,sizes[#sizes] do a[i] = i end   -- build auxiliary table
+for k in ipairs(sizes) do
+  local t = {table.unpack(a,1,k)}
+  assert(#t == k)
+  check(t, k, 0)
+  t = {1,2,3,table.unpack(a,1,k)}
+  check(t, k+3, 0)
+  assert(#t == k + 3)
+end
+
+
+-- testing tables dynamically built
+local lim = 130
+local a = {}; a[2] = 1; check(a, 0, 1)
+a = {}; a[0] = 1; check(a, 0, 1); a[2] = 1; check(a, 0, 2)
+a = {}; a[0] = 1; a[1] = 1; check(a, 1, 1)
+a = {}
+for i = 1,lim do
+  a[i] = 1
+  assert(#a == i)
+  check(a, mp2(i), 0)
+end
+
+a = {}
+for i = 1,lim do
+  a['a'..i] = 1
+  assert(#a == 0)
+  check(a, 0, mp2(i))
+end
+
+a = {}
+for i=1,16 do a[i] = i end
+check(a, 16, 0)
+do
+  for i=1,11 do a[i] = undef end
+  for i=30,50 do a[i] = true; a[i] = undef end   -- force a rehash (?)
+  check(a, 0, 8)   -- 5 elements in the table
+  a[10] = 1
+  for i=30,50 do a[i] = true; a[i] = undef end   -- force a rehash (?)
+  check(a, 0, 8)   -- only 6 elements in the table
+  for i=1,14 do a[i] = true; a[i] = undef end
+  for i=18,50 do a[i] = true; a[i] = undef end   -- force a rehash (?)
+  check(a, 0, 4)   -- only 2 elements ([15] and [16])
+end
+
+-- reverse filling
+for i=1,lim do
+  local a = {}
+  for i=i,1,-1 do a[i] = i end   -- fill in reverse
+  check(a, mp2(i), 0)
+end
+
+-- size tests for vararg
+lim = 35
+function foo (n, ...)
+  local arg = {...}
+  check(arg, n, 0)
+  assert(select('#', ...) == n)
+  arg[n+1] = true
+  check(arg, mp2(n+1), 0)
+  arg.x = true
+  check(arg, mp2(n+1), 1)
+end
+local a = {}
+for i=1,lim do a[i] = true; foo(i, table.unpack(a)) end
+
+
+-- Table length with limit smaller than maximum value at array
+local a = {}
+for i = 1,64 do a[i] = true end    -- make its array size 64
+for i = 1,64 do a[i] = nil end     -- erase all elements
+assert(T.querytab(a) == 64)    -- array part has 64 elements
+a[32] = true; a[48] = true;    -- binary search will find these ones
+a[51] = true                   -- binary search will miss this one
+assert(#a == 48)               -- this will set the limit
+assert(select(4, T.querytab(a)) == 48)  -- this is the limit now
+a[50] = true                   -- this will set a new limit
+assert(select(4, T.querytab(a)) == 50)  -- this is the limit now
+-- but the size is larger (and still inside the array part)
+assert(#a == 51)
+
+end  --]
+
+
+-- test size operation on tables with nils
+assert(#{} == 0)
+assert(#{nil} == 0)
+assert(#{nil, nil} == 0)
+assert(#{nil, nil, nil} == 0)
+assert(#{nil, nil, nil, nil} == 0)
+assert(#{1, 2, 3, nil, nil} == 3)
+print'+'
+
+
+local nofind = {}
+
+a,b,c = 1,2,3
+a,b,c = nil
+
+
+-- next uses always the same iteraction function
+assert(next{} == next{})
+
+local function find (name)
+  local n,v
+  while 1 do
+    n,v = next(_G, n)
+    if not n then return nofind end
+    assert(_G[n] ~= undef)
+    if n == name then return v end
+  end
+end
+
+local function find1 (name)
+  for n,v in pairs(_G) do
+    if n==name then return v end
+  end
+  return nil  -- not found
+end
+
+
+assert(print==find("print") and print == find1("print"))
+assert(_G["print"]==find("print"))
+assert(assert==find1("assert"))
+assert(nofind==find("return"))
+assert(not find1("return"))
+_G["ret" .. "urn"] = undef
+assert(nofind==find("return"))
+_G["xxx"] = 1
+assert(xxx==find("xxx"))
+
+-- invalid key to 'next'
+checkerror("invalid key", next, {10,20}, 3)
+
+-- both 'pairs' and 'ipairs' need an argument
+checkerror("bad argument", pairs)
+checkerror("bad argument", ipairs)
+
+print('+')
+
+a = {}
+for i=0,10000 do
+  if math.fmod(i,10) ~= 0 then
+    a['x'..i] = i
+  end
+end
+
+n = {n=0}
+for i,v in pairs(a) do
+  n.n = n.n+1
+  assert(i and v and a[i] == v)
+end
+assert(n.n == 9000)
+a = nil
+
+do   -- clear global table
+  local a = {}
+  for n,v in pairs(_G) do a[n]=v end
+  for n,v in pairs(a) do
+    if not package.loaded[n] and type(v) ~= "function" and
+       not string.find(n, "^[%u_]") then
+      _G[n] = undef
+    end
+    collectgarbage()
+  end
+end
+
+
+--
+
+local function checknext (a)
+  local b = {}
+  do local k,v = next(a); while k do b[k] = v; k,v = next(a,k) end end
+  for k,v in pairs(b) do assert(a[k] == v) end
+  for k,v in pairs(a) do assert(b[k] == v) end
+end
+
+checknext{1,x=1,y=2,z=3}
+checknext{1,2,x=1,y=2,z=3}
+checknext{1,2,3,x=1,y=2,z=3}
+checknext{1,2,3,4,x=1,y=2,z=3}
+checknext{1,2,3,4,5,x=1,y=2,z=3}
+
+assert(#{} == 0)
+assert(#{[-1] = 2} == 0)
+for i=0,40 do
+  local a = {}
+  for j=1,i do a[j]=j end
+  assert(#a == i)
+end
+
+-- 'maxn' is now deprecated, but it is easily defined in Lua
+function table.maxn (t)
+  local max = 0
+  for k in pairs(t) do
+    max = (type(k) == 'number') and math.max(max, k) or max
+  end
+  return max
+end
+
+assert(table.maxn{} == 0)
+assert(table.maxn{["1000"] = true} == 0)
+assert(table.maxn{["1000"] = true, [24.5] = 3} == 24.5)
+assert(table.maxn{[1000] = true} == 1000)
+assert(table.maxn{[10] = true, [100*math.pi] = print} == 100*math.pi)
+
+table.maxn = nil
+
+-- int overflow
+a = {}
+for i=0,50 do a[2^i] = true end
+assert(a[#a])
+
+print('+')
+
+
+do    -- testing 'next' with all kinds of keys
+  local a = {
+    [1] = 1,                        -- integer
+    [1.1] = 2,                      -- float
+    ['x'] = 3,                      -- short string
+    [string.rep('x', 1000)] = 4,    -- long string
+    [print] = 5,                    -- C function
+    [checkerror] = 6,               -- Lua function
+    [coroutine.running()] = 7,      -- thread
+    [true] = 8,                     -- boolean
+    [io.stdin] = 9,                 -- userdata
+    [{}] = 10,                      -- table
+  }
+  local b = {}; for i = 1, 10 do b[i] = true end
+  for k, v in pairs(a) do
+    assert(b[v]); b[v] = undef
+  end
+  assert(next(b) == nil)        -- 'b' now is empty
+end
+
+
+-- erasing values
+local t = {[{1}] = 1, [{2}] = 2, [string.rep("x ", 4)] = 3,
+           [100.3] = 4, [4] = 5}
+
+local n = 0
+for k, v in pairs( t ) do
+  n = n+1
+  assert(t[k] == v)
+  t[k] = undef
+  collectgarbage()
+  assert(t[k] == undef)
+end
+assert(n == 5)
+
+
+do
+  print("testing next x GC of deleted keys")
+  -- bug in 5.4.1
+  local co = coroutine.wrap(function (t)
+    for k, v in pairs(t) do
+        local k1 = next(t)    -- all previous keys were deleted
+        assert(k == k1)       -- current key is the first in the table
+        t[k] = nil
+        local expected = (type(k) == "table" and k[1] or
+                          type(k) == "function" and k() or
+                          string.sub(k, 1, 1))
+        assert(expected == v)
+        coroutine.yield(v)
+    end
+  end)
+  local t = {}
+  t[{1}] = 1    -- add several unanchored, collectable keys
+  t[{2}] = 2
+  t[string.rep("a", 50)] = "a"    -- long string
+  t[string.rep("b", 50)] = "b"
+  t[{3}] = 3
+  t[string.rep("c", 10)] = "c"    -- short string
+  t[function () return 10 end] = 10
+  local count = 7
+  while co(t) do
+    collectgarbage("collect")   -- collect dead keys
+    count = count - 1
+  end
+  assert(count == 0 and next(t) == nil)    -- traversed the whole table
+end
+
+
+local function test (a)
+  assert(not pcall(table.insert, a, 2, 20));
+  table.insert(a, 10); table.insert(a, 2, 20);
+  table.insert(a, 1, -1); table.insert(a, 40);
+  table.insert(a, #a+1, 50)
+  table.insert(a, 2, -2)
+  assert(a[2] ~= undef)
+  assert(a["2"] == undef)
+  assert(not pcall(table.insert, a, 0, 20));
+  assert(not pcall(table.insert, a, #a + 2, 20));
+  assert(table.remove(a,1) == -1)
+  assert(table.remove(a,1) == -2)
+  assert(table.remove(a,1) == 10)
+  assert(table.remove(a,1) == 20)
+  assert(table.remove(a,1) == 40)
+  assert(table.remove(a,1) == 50)
+  assert(table.remove(a,1) == nil)
+  assert(table.remove(a) == nil)
+  assert(table.remove(a, #a) == nil)
+end
+
+a = {n=0, [-7] = "ban"}
+test(a)
+assert(a.n == 0 and a[-7] == "ban")
+
+a = {[-7] = "ban"};
+test(a)
+assert(a.n == nil and #a == 0 and a[-7] == "ban")
+
+a = {[-1] = "ban"}
+test(a)
+assert(#a == 0 and table.remove(a) == nil and a[-1] == "ban")
+
+a = {[0] = "ban"}
+assert(#a == 0 and table.remove(a) == "ban" and a[0] == undef)
+
+table.insert(a, 1, 10); table.insert(a, 1, 20); table.insert(a, 1, -1)
+assert(table.remove(a) == 10)
+assert(table.remove(a) == 20)
+assert(table.remove(a) == -1)
+assert(table.remove(a) == nil)
+
+a = {'c', 'd'}
+table.insert(a, 3, 'a')
+table.insert(a, 'b')
+assert(table.remove(a, 1) == 'c')
+assert(table.remove(a, 1) == 'd')
+assert(table.remove(a, 1) == 'a')
+assert(table.remove(a, 1) == 'b')
+assert(table.remove(a, 1) == nil)
+assert(#a == 0 and a.n == nil)
+
+a = {10,20,30,40}
+assert(table.remove(a, #a + 1) == nil)
+assert(not pcall(table.remove, a, 0))
+assert(a[#a] == 40)
+assert(table.remove(a, #a) == 40)
+assert(a[#a] == 30)
+assert(table.remove(a, 2) == 20)
+assert(a[#a] == 30 and #a == 2)
+
+do   -- testing table library with metamethods
+  local function test (proxy, t)
+    for i = 1, 10 do
+      table.insert(proxy, 1, i)
+    end
+    assert(#proxy == 10 and #t == 10 and proxy[1] ~= undef)
+    for i = 1, 10 do
+      assert(t[i] == 11 - i)
+    end
+    table.sort(proxy)
+    for i = 1, 10 do
+      assert(t[i] == i and proxy[i] == i)
+    end
+    assert(table.concat(proxy, ",") == "1,2,3,4,5,6,7,8,9,10")
+    for i = 1, 8 do
+      assert(table.remove(proxy, 1) == i)
+    end
+    assert(#proxy == 2 and #t == 2)
+    local a, b, c = table.unpack(proxy)
+    assert(a == 9 and b == 10 and c == nil)
+  end
+
+  -- all virtual
+  local t = {}
+  local proxy = setmetatable({}, {
+    __len = function () return #t end,
+    __index = t,
+    __newindex = t,
+  })
+  test(proxy, t)
+
+  -- only __newindex
+  local count = 0
+  t = setmetatable({}, {
+    __newindex = function (t,k,v) count = count + 1; rawset(t,k,v) end})
+  test(t, t)
+  assert(count == 10)   -- after first 10, all other sets are not new
+
+  -- no __newindex
+  t = setmetatable({}, {
+    __index = function (_,k) return k + 1 end,
+    __len = function (_) return 5 end})
+  assert(table.concat(t, ";") == "2;3;4;5;6")
+
+end
+
+
+do   -- testing overflow in table.insert (must wrap-around)
+
+  local t = setmetatable({},
+            {__len = function () return math.maxinteger end})
+  table.insert(t, 20)
+  local k, v = next(t)
+  assert(k == math.mininteger and v == 20)
+end
+
+if not T then
+  (Message or print)
+    ('\n >>> testC not active: skipping tests for table library on non-tables <<<\n')
+else --[
+  local debug = require'debug'
+  local tab = {10, 20, 30}
+  local mt = {}
+  local u = T.newuserdata(0)
+  checkerror("table expected", table.insert, u, 40)
+  checkerror("table expected", table.remove, u)
+  debug.setmetatable(u, mt)
+  checkerror("table expected", table.insert, u, 40)
+  checkerror("table expected", table.remove, u)
+  mt.__index = tab
+  checkerror("table expected", table.insert, u, 40)
+  checkerror("table expected", table.remove, u)
+  mt.__newindex = tab
+  checkerror("table expected", table.insert, u, 40)
+  checkerror("table expected", table.remove, u)
+  mt.__len = function () return #tab end
+  table.insert(u, 40)
+  assert(#u == 4 and #tab == 4 and u[4] == 40 and tab[4] == 40)
+  assert(table.remove(u) == 40)
+  table.insert(u, 1, 50)
+  assert(#u == 4 and #tab == 4 and u[4] == 30 and tab[1] == 50)
+
+  mt.__newindex = nil
+  mt.__len = nil
+  local tab2 = {}
+  local u2 = T.newuserdata(0)
+  debug.setmetatable(u2, {__newindex = function (_, k, v) tab2[k] = v end})
+  table.move(u, 1, 4, 1, u2)
+  assert(#tab2 == 4 and tab2[1] == tab[1] and tab2[4] == tab[4])
+
+end -- ]
+
+print('+')
+
+a = {}
+for i=1,1000 do
+  a[i] = i; a[i - 1] = undef
+end
+assert(next(a,nil) == 1000 and next(a,1000) == nil)
+
+assert(next({}) == nil)
+assert(next({}, nil) == nil)
+
+for a,b in pairs{} do error"not here" end
+for i=1,0 do error'not here' end
+for i=0,1,-1 do error'not here' end
+a = nil; for i=1,1 do assert(not a); a=1 end; assert(a)
+a = nil; for i=1,1,-1 do assert(not a); a=1 end; assert(a)
+
+do
+  print("testing floats in numeric for")
+  local a
+  -- integer count
+  a = 0; for i=1, 1, 1 do a=a+1 end; assert(a==1)
+  a = 0; for i=10000, 1e4, -1 do a=a+1 end; assert(a==1)
+  a = 0; for i=1, 0.99999, 1 do a=a+1 end; assert(a==0)
+  a = 0; for i=9999, 1e4, -1 do a=a+1 end; assert(a==0)
+  a = 0; for i=1, 0.99999, -1 do a=a+1 end; assert(a==1)
+
+  -- float count
+  a = 0; for i=0, 0.999999999, 0.1 do a=a+1 end; assert(a==10)
+  a = 0; for i=1.0, 1, 1 do a=a+1 end; assert(a==1)
+  a = 0; for i=-1.5, -1.5, 1 do a=a+1 end; assert(a==1)
+  a = 0; for i=1e6, 1e6, -1 do a=a+1 end; assert(a==1)
+  a = 0; for i=1.0, 0.99999, 1 do a=a+1 end; assert(a==0)
+  a = 0; for i=99999, 1e5, -1.0 do a=a+1 end; assert(a==0)
+  a = 0; for i=1.0, 0.99999, -1 do a=a+1 end; assert(a==1)
+end
+
+do   -- changing the control variable
+  local a
+  a = 0; for i = 1, 10 do a = a + 1; i = "x" end; assert(a == 10)
+  a = 0; for i = 10.0, 1, -1 do a = a + 1; i = "x" end; assert(a == 10)
+end
+
+-- conversion
+a = 0; for i="10","1","-2" do a=a+1 end; assert(a==5)
+
+do  -- checking types
+  local c
+  local function checkfloat (i)
+    assert(math.type(i) == "float")
+    c = c + 1
+  end
+
+  c = 0; for i = 1.0, 10 do checkfloat(i) end
+  assert(c == 10)
+
+  c = 0; for i = -1, -10, -1.0 do checkfloat(i) end
+  assert(c == 10)
+
+  local function checkint (i)
+    assert(math.type(i) == "integer")
+    c = c + 1
+  end
+
+  local m = math.maxinteger
+  c = 0; for i = m, m - 10, -1 do checkint(i) end
+  assert(c == 11)
+
+  c = 0; for i = 1, 10.9 do checkint(i) end
+  assert(c == 10)
+
+  c = 0; for i = 10, 0.001, -1 do checkint(i) end
+  assert(c == 10)
+
+  c = 0; for i = 1, "10.8" do checkint(i) end
+  assert(c == 10)
+
+  c = 0; for i = 9, "3.4", -1 do checkint(i) end
+  assert(c == 6)
+
+  c = 0; for i = 0, " -3.4  ", -1 do checkint(i) end
+  assert(c == 4)
+
+  c = 0; for i = 100, "96.3", -2 do checkint(i) end
+  assert(c == 2)
+
+  c = 0; for i = 1, math.huge do if i > 10 then break end; checkint(i) end
+  assert(c == 10)
+
+  c = 0; for i = -1, -math.huge, -1 do
+           if i < -10 then break end; checkint(i)
+          end
+  assert(c == 10)
+
+
+  for i = math.mininteger, -10e100 do assert(false) end
+  for i = math.maxinteger, 10e100, -1 do assert(false) end
+
+end
+
+
+do   -- testing other strange cases for numeric 'for'
+
+  local function checkfor (from, to, step, t)
+    local c = 0
+    for i = from, to, step do
+      c = c + 1
+      assert(i == t[c])
+    end
+    assert(c == #t)
+  end
+
+  local maxi = math.maxinteger
+  local mini = math.mininteger
+
+  checkfor(mini, maxi, maxi, {mini, -1, maxi - 1})
+
+  checkfor(mini, math.huge, maxi, {mini, -1, maxi - 1})
+
+  checkfor(maxi, mini, mini, {maxi, -1})
+
+  checkfor(maxi, mini, -maxi, {maxi, 0, -maxi})
+
+  checkfor(maxi, -math.huge, mini, {maxi, -1})
+
+  checkfor(maxi, mini, 1, {})
+  checkfor(mini, maxi, -1, {})
+
+  checkfor(maxi - 6, maxi, 3, {maxi - 6, maxi - 3, maxi})
+  checkfor(mini + 4, mini, -2, {mini + 4, mini + 2, mini})
+
+  local step = maxi // 10
+  local c = mini
+  for i = mini, maxi, step do
+    assert(i == c)
+    c = c + step
+  end
+
+  c = maxi
+  for i = maxi, mini, -step do
+    assert(i == c)
+    c = c - step
+  end
+
+  checkfor(maxi, maxi, maxi, {maxi})
+  checkfor(maxi, maxi, mini, {maxi})
+  checkfor(mini, mini, maxi, {mini})
+  checkfor(mini, mini, mini, {mini})
+end
+
+
+checkerror("'for' step is zero", function ()
+  for i = 1, 10, 0 do end
+end)
+
+checkerror("'for' step is zero", function ()
+  for i = 1, -10, 0 do end
+end)
+
+checkerror("'for' step is zero", function ()
+  for i = 1.0, -10, 0.0 do end
+end)
+
+collectgarbage()
+
+
+-- testing generic 'for'
+
+local function f (n, p)
+  local t = {}; for i=1,p do t[i] = i*10 end
+  return function (_, n, ...)
+           assert(select("#", ...) == 0)  -- no extra arguments
+           if n > 0 then
+             n = n-1
+             return n, table.unpack(t)
+           end
+         end, nil, n
+end
+
+local x = 0
+for n,a,b,c,d in f(5,3) do
+  x = x+1
+  assert(a == 10 and b == 20 and c == 30 and d == nil)
+end
+assert(x == 5)
+
+
+
+-- testing __pairs and __ipairs metamethod
+a = {}
+do
+  local x,y,z = pairs(a)
+  assert(type(x) == 'function' and y == a and z == nil)
+end
+
+local function foo (e,i)
+  assert(e == a)
+  if i <= 10 then return i+1, i+2 end
+end
+
+local function foo1 (e,i)
+  i = i + 1
+  assert(e == a)
+  if i <= e.n then return i,a[i] end
+end
+
+setmetatable(a, {__pairs = function (x) return foo, x, 0 end})
+
+local i = 0
+for k,v in pairs(a) do
+  i = i + 1
+  assert(k == i and v == k+1)
+end
+
+a.n = 5
+a[3] = 30
+
+-- testing ipairs with metamethods
+a = {n=10}
+setmetatable(a, { __index = function (t,k)
+                     if k <= t.n then return k * 10 end
+                  end})
+i = 0
+for k,v in ipairs(a) do
+  i = i + 1
+  assert(k == i and v == i * 10)
+end
+assert(i == a.n)
+
+
+-- testing yield inside __pairs
+do
+  local t = setmetatable({10, 20, 30}, {__pairs = function (t)
+    local inc = coroutine.yield()
+    return function (t, i)
+             if i > 1 then return i - inc, t[i - inc]  else return nil end
+           end, t, #t + 1
+  end})
+
+  local res = {}
+  local co = coroutine.wrap(function ()
+    for i,p in pairs(t) do res[#res + 1] = p end
+  end)
+
+  co()     -- start coroutine
+  co(1)    -- continue after yield
+  assert(res[1] == 30 and res[2] == 20 and res[3] == 10 and #res == 3)
+  
+end
+
+print"OK"