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my name is BOS blim and today I'm going
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to talk to you about webm uh Ruby Jam
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for mocking HTTP requests so first a
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little bit about
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me um I've been developing software for
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over 20
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years and back in 2006 when I I was
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still a happy Java developer a friend of
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mine Andre chivda came to me and said
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hey have you heard of that language
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getting popular called
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truby and he sent me a link to that book
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uh I have seen a few copies
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yesterday and my life as a programmer
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has changed forever and I've been using
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kby ever
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since um I live in
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waro um but I work remotely since for
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that was
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popular and I'm the author and the
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single maintainer of
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webm um it's not the first year that I'm
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presenting about
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webm my previous presentation was back
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in
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2009 that's me back in
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London um and I decided to do an
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extrapolation of my
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presentations and I estimate that the
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next year I'll be presenting about webm
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Mo it's
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2039 so you have a unique chance to
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learn something about webm Mo
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today okay so uh what webm is for first
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webm allows you to stop HTTP requests
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but what does it mean it allows you to
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declare fake responses so that when your
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Ruby application makes an HTTP request a
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fake response will be returned instead
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of making a real HTTP
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connection and it also allows you to
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verify that request has been executed
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whether that was a sted request or a
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real
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request the idea is not original there
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was a gem called fake web before but it
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was not sufficient to my needs therefore
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I decided to create my own solution and
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I created webm the first version
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during a one day company
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hakon and what's important I created
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webm to address my own needs as a ruby
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developer and this needs happen to be
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the needs of many other Ruby
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developers and hence webm has been
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downloaded more than 270 million
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times uh it has almost 4,000 stars on
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GitHub um if you haven't started yes yet
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please do I'm aing for
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four um over 260 people
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contributed uh to webm Mo over the last
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15 years uh John Gallagher just
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yesterday thank
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you um and yeah including Ki so a few
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months ago Sam saffron the co-founder of
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this course submitted a poll request to
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webmo and he included a transcript of
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his conversation with Chad GPT
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fortunately CH GPT was completely
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useless in that case therefore we as
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human Ruby developers are still
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safe um webm is used by thousands of
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projects on GitHub and it's a dependency
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of thousands of uh registered Ruby
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jams um here are some of the popular uh
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Ruby projects that depend on webmock and
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if you haven't had a chance to use any
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of them then you probably used this
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one uh webm also inspired programmers in
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other languages who created similar
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Solutions okay so uh what does webmock
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offer well first it gives us this nice
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DSL uh that allows us to write a clean
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code uh to stop HTTP requests
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and it also gives us nice DSL to verify
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that requests have been executed and
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what's important is that both the of
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these dsls are HTTP client Library
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agnostic so once you write it you can
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use it with any HTTP client or switch
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HTTP clients without modifying your
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tests uh webm follows stab execute
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verify Paradigm which I borrowed from a
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Java test framework called
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mitao um and slightly different to what
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for example you can get used to with
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rspec what a single X declaration both
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creates the Stop and creates the
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expectation uh here this two steps are
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separated but it allows us to stab
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request without verifying that they have
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been executed or verify real request
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without stubbing
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them uh webm also allow allows us to run
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call backs after each
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request and this can be for example used
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for recording requests that have been
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executed um webm offers many features
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when stabbing so you can stop your
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request to time
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out or you can stop request with basic
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authentication or you can even record
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row responses with Carl and then declare
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stabs that will return this row
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responses um webm supports all popular
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HTTP clients in
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Ruby and it's supports all popular
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testing
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Frameworks okay so we know what are the
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basic features of webm but you might ask
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why mocking HTTP requests in the first
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place
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right so first first it allows you to
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run your test in isolation without an
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internet connection so if you came here
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uh by plane like me and you wanted to
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work on the plane uh webm is a perfect
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solution you can run your test without
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actually having access to an external
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API um it also allows you to avoid
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accidental changes to third party apis
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for example if you incorrectly configure
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your development or test environment
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with production credentials
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no changes will be made webm will
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prevent
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that um webm also allows you to run your
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test reliably so even if you have a weak
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internet connection or a third party API
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is currently down your tests will still
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run and the tests are fast because
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you're not depending on the current
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Internet connection or the fact that
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third party API is currently busy and
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and the respons are
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delayed and you can test all possible
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scenarios all edge cases you can test
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timeouts uh you can test 500 400
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responses and all this setup is done in
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Ruby so there is no need to make some
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setups remotely on a third party
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API but mocking HTTP can be useful also
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in other environments that test
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environment so for example you can
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develop without having an internet
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connection just you just need to declare
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some steps put them into a race
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initializer if it's a race application
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and you can run uh you can develop your
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app without having an internet
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connection on a plane uh you can also
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manually test your application and test
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various scenarios so you can test how
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your app will behave if a remote API
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times out or returns 500
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response um and you can also develop
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without actually having access to an
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external API so there was a project once
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that I worked on that heavily relied on
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a third party API and yet we haven't
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received access to that API for about
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one and a half month so what we have
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done we read the specification and
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documentation of that API we created
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some request stabs put them into race
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initializer and we're ready to go we
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developed and you can do the same in
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staging environments to demo the
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features that we have
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implemented um so this is how a sample
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uh race initializers with
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some uh with some request tabs can look
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like okay so we know that mocking HTTP
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requests can be useful sometimes uh um
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but why webm why would you use webm
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instead of creating your own solution or
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stubbing maybe HTTP client methods
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directly um so let's say you have this
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kind of code in your application and
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you're expected to change it to modify
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the
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functionality um so what do you do first
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well we want to do things properly we
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want to do things as first so first we
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find the corresponding test so we find
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the test and we find that Associated
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complicated setup so what do we do first
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what I would do is probably I would do G
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blame and check who wrote that
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complicated
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code just to realize yeah it was me a
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few years
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ago um and then I would import webm and
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replace that complicated
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setup with webmock
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DSL and now that I have a clean readable
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test I can modify the code so for
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example I can also change the code to be
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more readable by replacing net HTP with
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htpr RB which also gives us this nice
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DSL um webm is perfect for test driven
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development because of webm DSL you can
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focus on the functionality on testing
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the the the behavior not the implement
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so you can write your tests first
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without even deciding what HTP client
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you're going to use or what methods on
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that HTP client Library you're going to
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call uh but webm is also very useful for
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legacy application so usually what I
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will do uh when I
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inherit uh some uh Legacy Ruby
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application I'll will import webm and
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now I'm safe I can run my tests I can
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run a development without risking
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that the app is going to make an
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unexpected request to a third party API
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and if it does webm will not will let me
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know about
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this um webm allows us to
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stop uh your unescaped versions of the
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Euros so for example I find this code at
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the bottom way more readable than the
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one in the
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middle um and the feature I really like
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about webm is that if you declare your
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stop incorrectly or uh the stop is
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actually correct but the request is
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incorrect webm will stop the
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request and will'll provide you with
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this nice instructions on how this
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request is expected to be stopped so you
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can just copy and paste it into your
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test
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setup so basically webm exists to make
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our lives
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simpler uh but with that
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Simplicity with that DSL there is a cost
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the cost of not knowing what actually
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happens
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underneath and that might feel like
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magic a
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bit and a few months ago I went
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to chavier presentation where he
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explained
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how uh tid work Works
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internally and that got me inspired and
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I thought I'll do the same I'll explain
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how webm Mo Works
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internally but in order to understand
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how webm Works internally we first have
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to understand how HTTP clients
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work
00:13:17.760
so let's take a sample uh HTTP clients
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the typical client will usually provides
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an API uh which consists of some public
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methods
00:13:29.639
that usually represent HTTP
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verbs uh but these public methods
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usually do not do
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much uh so we can use them like
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that but yeah usually they don't do much
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there is usually some method or set of
00:13:52.000
methods that do all the heavy lifting
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underneath so let's call this for
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example let's call this method handle
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request
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so what this handle request method
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usually will do is it will first gather
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all the parameters that you have passed
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and it will build the request
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object and then it will send the request
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over HTTP or uh sorry TCP or SSL
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connection and upon receiving the
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response it will build the response
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object and if the uh HTP Library client
00:14:30.480
supports middleware it might also run
00:14:33.160
some
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middleware okay so now now that we
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understand how typical HTTP client works
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we can understand how web Works
00:14:46.079
internally so first stabby so when you
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do a stab declaration like that what
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webm will do underneath is it will
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create a request stop object
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and that request T object will be then
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registered in the global request T
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registry and request T object consist of
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two attributes so one is request pattern
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and request pattern contains all
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information required to match the
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request associated with that stuff and
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then it has a set of fake responses that
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are expected to be returned when a
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matching request
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appears and what's important is that the
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sub request method Returns the stab
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itself which allows us to chain it with
00:15:42.519
some additional calls so we can call it
00:15:45.199
with the width method and the width
00:15:49.079
method is to extend the request pattern
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so we can add additional criteria to
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match the request
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and again we are returning request St
00:16:01.240
object which allows us to chain it with
00:16:03.639
the to return method and to return
00:16:06.519
method adds a fake response to that stop
00:16:10.480
so when a request will be made matching
00:16:13.000
that request stop matching the request
00:16:15.199
pattern this declared fake response will
00:16:17.639
be
00:16:19.519
returned um request call backs um what
00:16:24.920
will happen if you call after request
00:16:27.000
webm will take this blog and register is
00:16:30.000
in the global request
00:16:35.440
registry
00:16:37.680
so we have we now have this Global stuff
00:16:41.600
registry we have the request stops we
00:16:45.199
have some call backs but still nothing
00:16:47.800
happens right so the if I now make an
00:16:50.160
HTTP request it won't be
00:16:53.560
affected and so what
00:16:56.800
actually does the work and intercept
00:16:59.360
this
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request is in webm are the adapters so
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webm has an adapter for each
00:17:08.039
HTTP Library so it will be a separate
00:17:12.079
adapter for curve or separate for net
00:17:16.280
HTTP um so to understand how an adapter
00:17:19.640
work like Works let's create a sample
00:17:22.959
adapter for our sample HTTP
00:17:27.120
client um so what an adapter will do it
00:17:31.480
will create a copy of a class that
00:17:35.360
contains our handle request method that
00:17:38.760
has all the heavy lifting it will create
00:17:41.039
that copy by sub
00:17:42.559
classing and then it will start monkey
00:17:46.440
patching that handle request method so
00:17:49.960
first it will after the request is built
00:17:54.240
webm will create the request signature
00:17:58.080
and the request sign signature contains
00:18:00.080
all necessary information to match the
00:18:02.880
request against the request
00:18:05.520
pattern and this request signature will
00:18:08.799
be registered in request
00:18:13.400
registry and then if there is a stop
00:18:16.520
found that matches that request
00:18:19.600
signature webm will return any declared
00:18:22.600
fake responses otherwise a real request
00:18:26.120
will be made
00:18:29.640
but yeah webm by default prevents all
00:18:33.200
real HTTP requests so in addition of
00:18:36.880
that it also has to check whether a real
00:18:38.799
request is allowed if it's allowed a
00:18:41.400
real request will be made and a real
00:18:43.760
response will be returned otherwise
00:18:46.080
webmock will return will raise an error
00:18:50.000
and after that error you will be
00:18:52.039
presented with this nice stubbing
00:18:56.320
instructions um after that if there are
00:18:58.880
callbox
00:18:59.919
registered uh webm will run them if
00:19:03.520
there is an middleware supported by the
00:19:06.280
HTTP client uh it will be run and then
00:19:09.880
uh response will be
00:19:12.520
returned so to recap request is built
00:19:15.760
then we build request signature and
00:19:17.679
register it in the request registry then
00:19:21.159
if there is a stop matching that request
00:19:23.200
we return a fake
00:19:24.760
response otherwise we check whether it's
00:19:27.960
allowed to make a real request and we
00:19:30.320
make it if not we raas an exception and
00:19:35.679
the nice instructions are
00:19:37.640
printed um the callbo are run middle one
00:19:42.000
is Middle Way is run and then uh
00:19:44.520
response is
00:19:45.840
returned so this is how an adapter Works
00:19:49.400
um okay but just by creating this copy
00:19:53.360
uh this monkey par copy of a clients uh
00:19:57.200
of this class still nothing happens
00:19:59.480
right if I call sample HTP client get
00:20:02.559
still a real class will be
00:20:05.120
used so we have to do something more so
00:20:08.120
what webm will do it will create first
00:20:10.360
create a reference uh to that original
00:20:14.320
uh to that original class and then it
00:20:17.240
will replace the original class with our
00:20:21.600
modified class with our monyer class by
00:20:23.799
using constant replacement
00:20:32.679
so yeah and uh and while this
00:20:37.760
solution uh you know might not sound
00:20:40.880
nice because we're doing Monkey patching
00:20:42.799
right and monkey patching is bad I quite
00:20:45.960
like it because we are not modifying the
00:20:48.159
original class we are just modifying the
00:20:49.840
copy and at any point we can call webm
00:20:52.400
disable and we can revert to the
00:20:54.200
original
00:20:57.360
state so so now when we call webm enable
00:21:00.960
all adapters will be enabled the created
00:21:04.520
copies of original classes will be
00:21:06.720
created and then Originals will be
00:21:09.080
replaced now when I call stop request a
00:21:12.640
request stop will be registered in
00:21:14.960
request
00:21:16.159
registry then when I call when I make
00:21:18.919
the real when I make the request a fake
00:21:22.279
response from the stuff will be
00:21:24.919
returned but now we can do something
00:21:27.400
more uh um so if you remember the
00:21:30.080
request signatures that we registered in
00:21:32.000
the request registry we can now verify
00:21:35.559
that request can actually been
00:21:46.000
made okay
00:21:49.360
so this is how web mock works as you can
00:21:53.559
see there is no magic this is just brute
00:21:57.840
monkey patching
00:22:01.080
um
00:22:03.200
and as I told you
00:22:05.679
earlier webm Mo I created webm Mo to
00:22:09.520
address my own needs as a ruby
00:22:12.880
developer but there was also another
00:22:15.720
factor that greatly affected me and
00:22:20.440
greatly influenced me to create
00:22:23.320
webm and that factor was
00:22:27.240
people so so back in
00:22:30.720
2009 when I created webm I lived in
00:22:33.279
London and I worked for a company called
00:22:35.760
new
00:22:36.720
bamboo and new bamboo was a team of very
00:22:41.400
passionate
00:22:43.600
developers
00:22:45.400
we inspired each
00:22:47.679
other we supported each other we shared
00:22:50.440
our passion for
00:22:51.960
Ruby uh we encourage each
00:22:55.039
other and during my 20 years of building
00:22:58.600
software
00:23:00.480
the thing I have learned is that the
00:23:03.640
most important factor for your growth as
00:23:06.320
a developer is the people you work with
00:23:09.559
and what you learn from
00:23:11.799
them therefore
00:23:14.600
when L stal said this
00:23:17.679
words I took it as a
00:23:20.840
compliment because to me Ruby was not
00:23:25.400
always not only about the nice syntax
00:23:27.760
not only about
00:23:30.039
it was always mainly about the
00:23:34.080
people the people who shared their
00:23:37.799
passion the people who are friendly to
00:23:40.400
each
00:23:41.760
other the people who Inspire each other
00:23:44.880
like on events like
00:23:47.919
this and people who are nice to each
00:23:51.600
other and I am really happy that I can
00:23:56.279
celebrate with all of you are passion
00:23:59.080
for Ruby
00:24:01.360
today thank you
