# Writing unit tests for your AO processes using the Test module

**Published by:** [BetterIDEa](https://paragraph.com/@betteridea/)
**Published on:** 2024-06-02
**URL:** https://paragraph.com/@betteridea/writing-unit-tests-for-your-ao-processes-using-the-test-module

## Content

Developing your decentralised applications on Arweave ao is simple, all you have to do is, create variables and functions to store and modify your data, then create handlers which will handle the incoming messages and call the defined functions accordingly :) But writing backend logic, that too for a radically new environment using a language that you might never have programmed in before, can be a daunting task. Moreover, you would not want there to be any loopholes in your code right? Well, fear not because in this guide we will be looking at how you can write unit tests for your functions using the unit testing module by Tom.First, a sneak peek!At the end of this article you will be able to create and run unit tests and get the results just the this screenshot:final outcomeDevelopment setupWe will be using BetterIDEa, which is an online IDE specialised for AO, as our development environment. Here you can easily install packages and write code in its notebook like ui To get started, visit ide.betteridea.dev and connect your web walletide.betteridea.dev home pageOnce connected, create a new project and give it a name you want. I’ll name it ‘how-to-unit-test‘. Next we need to tell the IDE which process it should run the code in, you can choose a previously created process or spawn a new one. I will create a new one and name it ‘unit-tester‘New project dialogAnd that’s it, hit create project and within seconds you’ll have your notebook up and running. Try running the default code and you should get an output saying “Hello AO!“IDE Notebook uiLet’s write some LUA!We’ll start simple, by creating a chatroom 🤭 Feel free to follow along and create multiple cells to write and run the different functions we will be makingInitialise a chatroom tableFunction to register a nicknameFunction to send a messageFunction to get all messagesInitialise a chatroom tableChatroom = { messages = {}, users = {} } return Chatroom Write the above code in a code cell and run it. You should get an output that prints an empty table with empty messages and users fields.Function to register nicknamefunction setNickname(userAddress, nickname) Chatroom.users[userAddress] = nickname end This code snippet adds an entry to the Chatroom.users field to store their nicknameFunction to send a messagefunction sendMessage(from, message, timestamp) local nickname = Chatroom.users[from] or "" local msg = { from = from, nickname = nickname, timestamp = timestamp, message = message } table.insert(Chatroom.messages, msg) end This code snippet checks if the user has a nickname, and appends message data to the Chatroom.messages tableFunction to get all messagesfunction getMessages() return Chatroom.messages end This function just returns all of the messages that have been sent in the chatroomVerify the code works as expectedTo check if these functions that we have defined work, let’s try running each of them one by one and see if they work. Starting with setNickname, if we pass our process id and a string, it should add an entry to Chatroom.usersresult of using setNickname()Next we try running the sendMessage function and pass our process id, the message and a timestamp (0 for testing), and can see that an item has been added to Chatroom.messagessendMessage()lastly, getMessages also works as expectedgetMessages()But, wait a minute… What if the user passes something other than the expected values?Fear not, we are going to add exactly that now :) For adding checks, we will use the assert function that lua provides, to make sure our conditions are met, else an error gets thrownsample usageassert(condition, "error message if condition is false") and we can put anything in condition, for example:whole variables to check if they have been definedsize of tables or stringscomparisons between variablesSome checkers we can add to our chatroom app are:Check if message is a stringCheck if size of ao.id is 43 (standard process id size)If timestamp is a number and nothing elseIf nickname has at least 3 charactersassert(type(userAddress) == "string", "user address should be a string") assert(#userAddress == 43, "invalid user address size") assert(#nickname >= 3, "nickname should be atleast 3 characters long") assert(type(message) == "string", "message should be a string") assert(#from == 43, "invalid process id size") assert(type(timestamp) == "number", "timestamp should be a number") Add the given snippets to the start of setNickname and sendMessage functions. Now if we call these functions with some unwanted data, it should throw errors like thiserrors thrown by the assert functionsUse the Test module to run automated unit testsHead over to the top right on the IDE and click on the Modules icon. A dialog box should open, asking you which module to load, simply select Test and hit load. (feel free to inspect the code that will be loaded on your process)Loading the Test moduleNow we can import the module using the require function. Lets try running the example code from the repos example.lua filelocal Test = require("Test") local myTests = Test.new('example tests') myTests:add("ok", function () assert(true, 'passing test') end) return myTests:run() example testsAnd as you can see it runs the tests and prints the results for passed and failed cases Lets create a tests for our chatroomlocal Test = require("Test") chatTests = Test.new('Chatroom unit tests') return chatTests Run this in a module and have a look at the resulttests tableLet’s create and add tests for our functions. To create a test, wrap your intended function around another function() … end block and pass it to the chatTests:add() function along with a name for this test Like this 👇chatTests:add("verify table", function() assert(type(Chatroom)=="table", "Chatroom is not a table") end) chatTests:add("verify users table", function() assert(type(Chatroom.users)=="table", "Chatroom.users is not a table") end) chatTests:add("verify messages table", function() assert(type(Chatroom.messages)=="table", "Chatroom.messages is not a table") end) To check the sendMessage functionChatroom.messages = {} chatTests:add("send message", function() sendMessage(ao.id, "hi", 0) end) chatTests:add("verify message sent:1", function() assert(#Chatroom.messages == 1, "Message was not logged") end) chatTests:add("verify message sent:1", function() assert(Chatroom.messages[1].message == "hi", "Message content is different") end) These tests send a message, then check in the Chatroom.messages table wether the message data was added accurately. Lastly add tests for checking the setNickname function, 2 of which are set to fail deliberatelychatTests:add("set nick", function() setNickname('O1d7qSBUEyDMBd8JuljtGo2vPhX-LFn5DUEObX2GCMc','ankush') end) chatTests:add("set nick", function() setNickname('7quc6o_k8O2DA0YD0sqZ0brsTVFhZVaRznNZ6KxahmY','weeblet') end) chatTests:add("set nick:fail", function() setNickname('illegal-id','weeblet') end) chatTests:add("set nick:fail", function() setNickname(ao.id,'aa') end) Feel free to add our own tests too 💡 Then finally we run the tests and look at the resultstest resultsWasn’t that simple 🤩You can access the full notebook here 👇 https://ide.betteridea.dev/import?id=7quc6o_k8O2DA0YD0sqZ0brsTVFhZVaRznNZ6KxahmY For any questions or if you need help, feel free to join the BetterIDEa discord community https://discord.gg/nm6VKUQBrA Thank you for reading ;)

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