【进阶实战】依赖注入：测试友好的模块装配封装

local function createRewardSender(mailFn)
    return function(actorName, itemId, num)
        if itemId == "" or num <= 0 then
            return false, "参数不合法"
        end
        return mailFn(actorName, itemId, num)
    end
end
-- 生产装配：真邮件
local prodSender = createRewardSender(function(actorName, itemId, num)
    sendmail("#" .. actorName, 0, "奖励发放", "请查收附件。", itemId .. "," .. num)
    return true
end
)
-- 测试装配：只记录不发
local testLog = {}
local testSender = createRewardSender(function(actorName, itemId, num)
    testLog[#testLog + 1] = { to = actorName, item = itemId, num = num }
    return true
end
)

local ok = testSender("无名小卒", "裁决之杖", 1)
assert(ok and #testLog == 1 and testLog[1].item == "裁决之杖")