replaceclosure

-- OUTPUT: https://i.imgur.com/27QcbEF.png

local original
local an_upvalue = "an upvalue"

local function dummy(a)
    print("in dummy: " .. tostring(a))
    return an_upvalue
end

local old_dummy, old_printconsole = dummy, printconsole

-- lclosure -> lclosure
print("lclosure -> lclosure")

original = assert(replaceclosure(dummy, function(a)
    print("in hook: " .. tostring(a))
    return original(a)
end))

dummy("1")
print(dummy == old_dummy)
assert(replaceclosure(dummy, original))
dummy("2")

-- lclosure -> cclosure
print("lclosure -> cclosure")

original = assert(replaceclosure(dummy, print))

dummy("3")
print(dummy == old_dummy)
assert(replaceclosure(dummy, original))
dummy("4")

-- cclosure -> lclosure
print("cclosure -> lclosure")

original = assert(replaceclosure(printconsole, function(a, ...)
    print("in hook: " .. a)
    original(a, ...)
end))

printconsole("5", 255, 0, 0)
print(printconsole == old_printconsole)
assert(replaceclosure(printconsole, original))
printconsole("6", 255, 0, 0)

-- cclosure -> cclosure
print("cclosure -> cclosure")

original = assert(replaceclosure(printconsole, warn))

printconsole("7", 255, 0, 0)
print(printconsole == old_printconsole)
assert(replaceclosure(printconsole, original))
printconsole("8", 255, 0, 0)

-- error tests
spawn(function()
    assert(replaceclosure(dummy, function()
        print(original, an_upvalue)
    end)) -- replacing dummy, which has 1 upvalue (an_upvalue), with a function that has 2 upvalues (original & an_upvalue) will throw an error
end)

spawn(function()
    original = assert(replaceclosure(dummy, function() end))
    assert(replaceclosure(dummy, function() end)) -- error here, cannot replace an already replaced closure with anything that isn't the original closure
end)