--- title: Testing puts output with RSpec, error handling snippets slug: testing-puts-output-with-rspec-error-handling-snippets published_at: 2022-04-13 12:00:18 +0000 updated_at: 2026-03-04 20:13:34 +0000 summary: description: tags: [cjav_dev, web development tutorials, web development for beginners, vim, ruby, rspec, error handling, @cjav_dev] views: 696 author: CJ Avilla url: https://www.cjav.dev/videos/testing-puts-output-with-rspec-error-handling-snippets youtube_url: https://www.youtube.com/watch?v=SbbjTc3gCHI youtube_id: SbbjTc3gCHI embed_url: https://www.youtube.com/embed/SbbjTc3gCHI thumbnail_url: https://i.ytimg.com/vi/SbbjTc3gCHI/hqdefault.jpg type: video --- # Testing puts output with RSpec, error handling snippets *Published: April 13, 2022* *Views: 696* ## Watch [Watch on YouTube](https://www.youtube.com/watch?v=SbbjTc3gCHI) [![Testing puts output with RSpec, error handling snippets](https://i.ytimg.com/vi/SbbjTc3gCHI/hqdefault.jpg)](https://www.youtube.com/watch?v=SbbjTc3gCHI) ## Description ## Transcript hey what's up welcome back in this episode we're going to talk about error handling we're also going to talk a little bit about uh r spec and how do you how you can test the output of a function so it's going to be just a super quick ruby episode here um where we're going to write some write some tests so i've got this little thing that i'm working on so we are improving the error handling documentation as part of the stripe docks and there are some examples here and i am kind of like helping out writing the code snippets and one of the things that i wanted to do was um write some tests around these and so i thought it might be fun to just like jump in and show how i might test this out so the first thing is i'm going to actually put my real api key so that our tests actually run and the idea is that if you call this example function with um some arguments like the amount and a currency and then maybe a payment method so there's a bunch of test payment method strings you can use so like pm card visa now if we if we're to run this so down in the far left corner i'm saying ruby errors dot rb so this is going to like actually execute the file and we see that no error was printed out i'm surprised by that because i think oh right we want to we want to pass confirm true so it tries to actually confirm the payment intent right now um okay no error if we take out the currency though then we get this invalid request occurred and so right now on the dock we have this uh this error to trigger thing where you can say like show me um the params that i would pass if i got an invalid request or show me the params i would pass if i want to get a card error and all of these are sort of showing the output that you would see if we passed in one of the test cards that is used for you know a decline or whatever and so if we look at the docs for the testing cards there's actually like a bunch of test cards or test payment method strings but what i want to do is i'm actually want to like i want to print out the error message as part of each of these errors that we're handling and in order to do that i need to kind of like make sure that the code that i'm changing in the snippet is not going to break and so one thing that i wanted to do was just write some inline r spec tests so right here i can say require r spec just directly in line in this file and i'm actually going to just get rid of that and say rspec.describe example function and then inside of here i want to have like a new test that says something like it handles uh card error and then inside of here i want to exercise that example function so i'm going to call in fact i might even grab like the snippet here that we expect to fire a card error and then if we were to just run it right now so we can actually just run like r spec errors.rb and it should run the specs the same way that you would expect if you had like a separate lib and spec directory and so we can see that it did pass but we got a this message an error occurred your card was declined so our spec provides you this this handy tool where you can pass a block into an expect function and then expect that it's going to output something so we can say expect that the stuff inside of this block is going to output so we can say like.2 output i think and then we can pass in a string a card error blah blah blah and then we want to say dot uh to standard out because when we say puts we're just printing directly out to standard out it's not to standard error or anything else like that probably i don't know like in practice maybe we should be logging these out to standard error but um the example is more about how do you handle a certain exception type versus like how do you log it so i think this is okay so if we run this again it says undefined method two output i think maybe it's two output like this let's see we want to expect that that okay cool so yeah so we're expecting that that running this block will output something and it's not a card error it's going to be a card error occurred your card was declined so that's actually what we want inside of our expectation here and it has a new line and i'll probably put this down a little bit here so this is this is kind of like how we might um build expectations around an output so around this put statement now i want to improve this one a little bit so that it prints out the error and error message but first let's just write a little test for it so we're going to say it handles an invalid request error and then the invalid request error is actually going to be a little bit different so if we go to the invalid request this one is just missing the currency but it's passing pm card visa which is a valid card so we're going to remove the currency and we'll add in this same sort of like comment here and now we're going to expect that it's going gonna output something different so i'm gonna run it without any um any output expectation there and it'll tell me like okay an invalid request occurred but i wanted to print out more than that i want it to print out something like an invalid request occurred like missing missing param currency which is i think what will come from the stripe api if we did this right so let's see what we get back missing param currency is not included because our actual implementation does not include that yet so i'm going to say after this in fact like i want a period at the end of that sentence also now i can say e dot error.message which is where the message is going to be stored so if we rerun this we will see okay and oh missing required param currency and then it has okay uh missing required ram currency is that right let's see maybe there's no space after yeah okay there's no space after the new line i don't know and then i think what i actually need is to use um yeah i need to use double quotes here right because it's i'm using that new line character um that always throws me off okay now what's different did i spell something wrong missing required param currency so an invalid request occurred okay let's see that's what it should be i think [Music] what is the diff do you see the diff was this the one i'm supposed to copy let's see oh does this one not have wait i wonder is that the one that's failing am i not failing the other one what's going on here wait a card error occurred your card was declined and it output your card oh wait there's two there's two okay you know what i added a period up here and then i didn't i didn't realize that i was i was causing the other test to break okay that's why you only change one thing at a time all right now we have two passing tests so that's pretty cool um another one though that gets a little bit trickier is then when we're trying to handle something like a stripe error which is just a generic all right so we want to expect that it handles a stripe error so we're going to add this new assertion handles stripe error and then for now we'll just say this is some other this is going to be some other other error message and if we attempt to run this now we should get just the same sort of generic failure before because it was missing currency but if we say currency is usd um then what we want to do is actually like explicitly cause an authentication error and there's a couple ways we could do this um one would be to just sort of set the api key globally or like set the api key per request somehow so that it failed like maybe we say like stripe.api key is like invalid here but if we were to run this and the tests run out of order then it's going to globally set the api key to invalid for like all the other subsequent tests so instead of doing this globally what we want to do is create a new client so we're going to say stripe stripe client dot new and pass in invalid api key here and then we can say something like re client.request do and then everything that's inside of this block will run in the context of that client this is like one of the ways that you can instrument things to happen um but basically we're expecting this is going to be like an authentication error message thing i'm not actually sure what the error message is yet so i'm just going to run it like this and then we are going to see this error here so another problem occurred unrelated to stripe invalid api key provided and then it has like something something something key so this is actually what we want so i'm going to grab that and then paste it in here maybe unrelated to stripe blah blah blah okay so let's see if this is now passing another way that we could have done it is sort of like maybe stubbed out we could have stubbed out the payment intent create method that's inside of our example function here we could have like said if this fires then make sure that it raises a specific exception type like maybe it just raises stripe error and then it goes into this this block and then we could make sure that that actually happens i don't know there's a couple different ways we could have done that i guess um let's see um we also want an assertion to make sure it prints out no error it handles or like it works or like prints in the success case or something and then we can just remove all of this fanciness around here and we're gonna expect that if we have the right keys and everything that we're gonna print out no error all right let's see if that works okay we expected no error but we got no error with a new line and of course all right fantastic so now what we have is a tested code snippet we know for sure that the error messages are printing out we know for sure that it works in all of these different cases and we have like examples that we can show uh in the dock for all of those now we have to just go write it in all the other languages so um this is always a really handy tool that i like dropping just like dropping in an r spec or even if you're using some other test framework right dropping that in in line as you're working on something can be really helpful so that you can ensure that as you're changing things you're not breaking other things as you noticed as soon as i added a dot to this output message while i was working on the test for this one i broke the other test and that gives me a lot of confidence that this is working as expected because i have everything sort of tested all the different cases are tested um so yeah this is uh hopefully this is useful thanks so much for watching and we'll see in the next one --- [Back to all videos](https://www.cjav.dev/videos) --- ## Hey Agent, thanks for visiting! 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