Building Data-Driven Web Apps with Pyramid and SQLAlchemy Transcripts
Chapter: Testing web apps
Lecture: Concept: view method tests
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0:00
Let's look at testing these views again.
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We're just passing in the requests
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The view method probably works with the view model
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but it doesn't have to.
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We also saw this view method probably talks to the database
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and that can become a challenge.
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So let's see how that works.
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Well, we're going to say test the home page.
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So we're going to do our Arrange which means
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we import the action method called index
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in our HomeController we had a function called index
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that maps to /. In order to call it, which is what we want to do
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we have to pass a request.
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So as we've seen before we create the dummy request
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and we're going to just call index passing the request
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and getting the model that returned back, back.
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And in our world there's supposed to be
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a packages list on the homepage
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so we can show the latest releases.
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So we're going to grab that out of the dictionary
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and then assert that there's at least one package in it.
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We're also asserting that the key exists
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'cause the square brackets would be a key error
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but we could get it the other way, right?
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So there's no, There's not the absence of packages.
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They are being passed, right.
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This might not be the best test for the homepage
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but it demonstrates the kinds of things you would look for.
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Well this is cute right. Where'd those packages come from though?
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They came from the database didn't they?
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So chances are this won't even work
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and if it did work it's probably talking to the database
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by some miraculous way and you want to not let it do that.
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You want to control where it gets it's data from
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so let's look at a more realistic view.
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Now, for the more realistic view we need more room.
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Okay, but let's suppose we're trying to get ahold
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of the package details
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and we want to do that by requesting
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a certain package but not actually going to the database.
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Again we're going to Arrange and get our project method
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our project view from the PackageController.
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And we're also going to work with package
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'cause we need to create some test data.
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We're going to get our fake request.
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We're going to create some fake package data
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and we put that into a function
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and it could be really elaborate, we don't need to worry
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about the details we just allocate a new package objects
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give it a bunch of releases and properties
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and so on right there.
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Our request has a package name which is SQLAlchemy.
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Now apparently we use Get so it's like query string
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but whatever, matchdict, query string
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whatever your app does we say
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request, here's what they're asking for, SQLAlchemy.
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And then in order to intercept a database behavior
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we're going to define a with block for
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pypi.services.package_service.package_by_id
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and also one, in this case imagine we're calling it
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a function, releases_for_package
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rather than using the SQLAlchemy relationship.
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So we're going to intercept both of these
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and then we're going to finally act.
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Just call the function with the fake request
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and the fake underlying database methods.
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Boom, out comes your info
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and then finally we can assert around that.
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Get us thing back, we'll call it web package
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to make it not ambiguous.
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By pulling that out of the model return
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and we can assert things like its id is SQLAlchemy
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and it has two releases which are
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create fake package data, give it. Things like that.
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This let's us create isolated tests
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by both passing in required infrastructure
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and replacing it behind the scenes with Patch.
