A couple of weeks ago I migrated a React project using redux to <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/">Redux Toolkit</a>.
Redux has always been my preferred state management tool for React (which doesn&#x27;t mean I &quot;love&quot; it), but one of its main problems is the amount of boilerplate code it requires.
Because of that I had a couple of helper functions, but there was still some things not properly handled, like proper type inference on reducers and actions (I use TypeScript).
A bit by accident (I think it was on Twitter), I found out about Redux Toolkit (RTK from now on), an official library from the redux team, which provides some opinionated helpers to reduce the amount of boilerplate, and I decided to give it a chance.
These are my impressions.
<h3>TL;DR</h3>
I first started to use it in a proof of concept, and I quickly loved it.
RTK does not &quot;replace&quot; any of the redux principles, so you can progressively adopt it, by replacing small bits of code. My plan was to use it just for some reducers, but I liked it so much that I ended up migrating the whole project in a series of consecutive pull requests.
<h3>A bit of context</h3>
Before the migration, I used to follow the <a target="_blank" rel="noopener noreferrer" href="https://github.com/erikras/ducks-modular-redux">ducks modular pattern</a>, which promotes putting all your action types, action creators and the reducer handling those actions on the same module.
This fits pretty well with RTK, as in most of the cases you will use <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createSlice">slices</a>, and end up exporting the reducer and action creators returned by it, from the same module.
If you use <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createAsyncThunk">async thunks</a>, they usually need to be used by that same slice, so it&#x27;s not a bad idea to export them also from there.
<h3>Why I love it</h3>
There are a couple of reasons for which I loved RTK right away. The main one is that they make an impressive work on making type inference in TypeScript work properly.
<ul>
<li>Slices detect the type of the initial state in order to know what is expected to be passed as <code>state</code> to reducers.</li>
<li>You can infer the type of your store from what is generated by <code>configureStore</code> or <code>combineReducers</code> functions, allowing you to also properly type the <code>dispatch</code> function.</li>
<li>Action creators are generated with the proper param types based on the reducers provided to <code>createSlice</code> or the callback provided to <code>createAsyncThunk</code>.</li>
<li><code>createSlice</code> can consume all the action creators generated by <code>createAsyncThunk</code>, and infer the proper payload for each one of them.</li>
</ul>
Thanks to this, the code is super predictable and potential bugs can be caught sooner.
<blockquote>
More details on how to use RTK with typescript https://redux-toolkit.js.org/usage/usage-with-typescript
</blockquote>
But this is not the only benefit. Other reasons that make it very nice to work with are:
<ul>
<li>It keeps the same concepts from Redux, but removing the boilerplate or your own helper functions if you have them (yes, I didn&#x27;t want to keep all those <code>switch</code> statements everywhere).</li>
<li>It is mostly transparent for the components dispatching the actions or consuming the state.</li>
<li>All the tests covering your reducers/actions/components should keep passing, as the outcome from RTK is the same as if you built everything manually.</li>
<li>It introduces a couple of extra helpers, like <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/rtk-query/overview">RTK query</a> or the <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createListenerMiddleware">listener middleware</a>, which is very useful to dispatch actions as a result of other actions being dispatched.</li>
</ul>
<h3>Challenges I found</h3>
Of course, adopting a new tool always comes with some challenges.
The main &quot;problem&quot; I found is that RTK is a bit opinionated, but that&#x27;s precisely how they manage to reduce boilerplate code, and it&#x27;s also &quot;advertised&quot; in their website, so not a big surprise.
I usually prefer to be in control of everything (configuration over convention), but that&#x27;s just a personal preference, and sometimes it&#x27;s ok to accept a bit of magic for the sake of simplicity.
This caused the next challenges for my particular case:
<ul>
<li>
RTK assumes your project follows a strict <a target="_blank" rel="noopener noreferrer" href="https://redux.js.org/tutorials/fundamentals/part-7-standard-patterns#flux-standard-actions">Flux pattern</a>, meaning your actions always have the properties <code>type</code>, <code>payload</code> and optionally <code>meta</code> and <code>error</code>.
I was not following this pattern (my actions had the payload &quot;mixed&quot; on the first object level), so I had to adapt all my actions first, fix the tests, then migrate the reducer to RTK and make sure the tests kept passing.
<div></div>
</li>
<li>
Immutability is no longer promoted in reducers. Instead, the library requires <a target="_blank" rel="noopener noreferrer" href="https://immerjs.github.io/immer/">immer</a> internally, and using proxies they automatically ensure immutability, even if you &quot;mutate&quot; the state.
This feels a bit counterintuitive at first, because redux always promoted an immutable approach, and the use of immer is not obvious.
However, they have <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/usage/immer-reducers#why-immer-is-built-in">good reasons</a> to do it, and if your reducers return a state object, you can still use the immutable approach. It&#x27;s up to you.
<div></div>
</li>
<li>
Action creators resulting of <code>createAsyncThunk</code> can only have one argument.
This is because the async thunk callback receives a second argument containing the <code>dispatch</code> and <code>getState</code> functions, as well as a couple of other goodies, enforcing this convention to avoid human errors.
<div></div>
</li>
<li>
You cannot dispatch other actions after the callback passed to <code>createAsyncThunk</code>, because it has to return the payload and RTK dispatches the action for you.
However, this is probably something you usually should not be doing, and in my case, I resolved it with the <a target="_blank" rel="noopener noreferrer" href="https://redux-toolkit.js.org/api/createListenerMiddleware">listener middleware</a>, listening for the second action in order to dispatch the second one.
</li>
</ul>
<h3>Conclusion</h3>
My conclusion is that RTK is definitely worth it if you use redux.
It makes code simpler, more predictable and better typed. However, it still requires knowing how redux works internally and what are its patterns, in order to understand why the library exposes the helpers it exposes and why.
For existing redux projects, you can migrate progressively, addressing the challenges bit by bit and not all at once, which simplifies its adoption.
For new projects in which you want to use redux, I would recommend starting right away with RTK.

A couple of weeks ago I migrated a React project using redux to Redux Toolkit. Redux has always been my preferred state management tool for React (which doesn't mean I "love" it), but one of its main problems is the amount of boilerplate code it requires.

Because of that I had a couple of helper…

My experience migrating to Redux Toolkit (RTK)

In 2019, GitHub published their own solution to run automated workflows called GitHub Actions, which allowed those hosting their code in GitHub, to be able to define and run their CI/CD pipelines in the same platform. When it was released, one of the main pain points to use it was that defining…

How to reduce duplication in your GitHub Actions workflows

Recently ReactJS v18 was released. I started to look into its improvements, and checked which of my projects could benefit from them.
The main react-based project I maintain at the moment of writing this article is <a target="_blank" rel="noopener noreferrer" href="https://github.com/shlinkio/shlink-web-client">shlink-web-client</a>, so I naturally created a new branch and started the process.
The update was quite smooth, as most of the other dependencies I was using from the react ecosystem were already updated to support v18. All but one, <a target="_blank" rel="noopener noreferrer" href="https://enzymejs.github.io/enzyme/">enzyme</a>, the testing framework I was using to unit-test react components.
To be precise, I was able to continue running my tests, but some of them (those using <code>mount</code> instead of <code>shallow</code>) were still rendering components with the &quot;old&quot; React v17 approach, causing them to behave as in that version and a warning being printed in the console.
<h3>First fix attempt</h3>
The way enzyme integrates with the react version you are using is through an adapter library. The last official one supports only React v16, but someone released an <a target="_blank" rel="noopener noreferrer" href="https://github.com/wojtekmaj/enzyme-adapter-react-17">unofficial adapter for v17</a> which, with close to 650k weekly downloads, quickly became the way to go.
I checked if there was one for React 18, but sadly there wasn&#x27;t.
Also, the author of the adapter for v17 posted an article indicating <a target="_blank" rel="noopener noreferrer" href="https://dev.to/wojtekmaj/enzyme-is-dead-now-what-ekl">enzyme is dead</a>, he was not going to release one for v18, and publishing one for v17 was a mistake.
With those facts in mind, I started to face what was probably going to be the moment to migrate to <a target="_blank" rel="noopener noreferrer" href="https://testing-library.com/docs/react-testing-library/intro">react testing library</a>.
<h3>Migration strategy</h3>
I decided to follow a migration strategy similar to the one suggested in the article above, but with a couple of modifications:
<ul>
<li>I update to React 18 anyway, as tests still pass.</li>
<li>Migrate right away all tests using <code>mount</code>, as those are the ones behaving differently.</li>
<li>New tests should be written directly with react testing library (RTL from now on).</li>
<li>When an existing test needs to be changed, consider migrating it to RTL, and do it if there&#x27;s time.</li>
<li>Introduce some PR from time to time just migrating a handful of tests.</li>
<li>Once everything is migrated, get rid of everything related with enzyme.</li>
</ul>
<h3>First contact and impressions</h3>
I was a bit sceptical with RTL, as it was focused more on integration tests, instead of unit tests, which meant I had to completely change the mindset to write tests.
It also didn&#x27;t support shallow rendering, meaning that you will end up sometimes rendering a bigger component tree when testing container-like components, potentially causing side effects that could affect your test.
On the other hand there&#x27;s more and more people stating that <a target="_blank" rel="noopener noreferrer" href="https://kentcdodds.com/blog/why-i-never-use-shallow-rendering">shallow rendering is an anti-pattern</a>, and that&#x27;s probably the reason of enzyme getting &quot;discontinued&quot;.
Also, RTL has become the <a target="_blank" rel="noopener noreferrer" href="https://reactjs.org/docs/testing.html#tools">officially recommended framework</a> to test react components, it has become very popular, and it has even joined a wider group of testing libraries under the <a target="_blank" rel="noopener noreferrer" href="https://testing-library.com/"><code>@testing-library</code></a> organization.
The thing is that I started to use it, and I was quickly surprised with how it felt to work with it, and all the benefits it was bringing to my tests.
<h3>Benefits I have experienced</h3>
Once I started migrating the first tests I noticed some benefits:
<ul>
<li>Changing my mindset was actually easier than I thought. The docs are very well written, so it&#x27;s relatively easy to start using RTL.</li>
<li>My tests got simpler, and required less of those nasty global mocks that jest allows (I&#x27;m looking at you, <a target="_blank" rel="noopener noreferrer" href="https://jestjs.io/es-ES/docs/mock-functions#mocking-modules"><code>jest.mock</code></a>).</li>
<li>Tests were way less coupled with implementation details. I moved from testing the component props, to test what the user would see on the screen.</li>
<li>Related with previous point, I started to write my tests by looking at the screen instead of the component&#x27;s implementation.</li>
<li>Changes in source code led to fewer tests requiring to be changed.</li>
<li>A progressive migration was possible, where some tests still use enzyme and others are already using RTL.</li>
</ul>
And overall, it felt good and I have already dedicated a couple of PRs just to migrate more tests.
<h3>Challenges I faced</h3>
But of course, migrating to a new tool always comes with its own challenges, and this was not an exception. I&#x27;ll explain the main ones I have faced so far and how I tackled them:
<ul>
<li>
RTL lets you do some things in a couple of different ways, and the docs may not be super clear about what&#x27;s the recommended option.
For this I recommend reading <a target="_blank" rel="noopener noreferrer" href="https://acel.me/DCMb1">this article</a> from Kent C. Dodds, RTL&#x27;s author, which explains some common mistakes when using the library.
</li>
<li>
At first, I struggled a bit with asynchronous side effects and state changes in components, which can easily end up printing a warning like <code>Warning: An update to MyComponent inside a test was not wrapped in act</code>.
The warning also explains how you are supposed to solve this by wrapping your code in <code>act()</code>, but this warning comes from React, not RTL, and what it is not telling you is that RTL already wraps all needed operations in <code>act()</code>.
What this error usually mean is that you are not waiting for something to happen. <a target="_blank" rel="noopener noreferrer" href="https://acel.me/jnUdT">This other article</a>, also from Kent C. Dodds, explains everything you need to know about the things that can lead to this warning, and how to solve them.
</li>
<li>
Since you start testing from the user point of view, some use cases can be challenging to test without coupling with implementation details. For example, when you have a component which dynamically renders different images or icons, I used to directly check the component properties.
For this I found the best solution was to use <a target="_blank" rel="noopener noreferrer" href="https://jestjs.io/docs/snapshot-testing">jest snapshots</a>. I didn&#x27;t want to manually check which SVG was being rendered in the DOM, just that different ones were being used in every case.
<pre class="language-tsx"><code class="language-tsx">// I went from this...
test(&#x27;...&#x27;, () =&gt; {
 const wrapper = shallow(&lt;MyComp dynamicValue=&quot;foo&quot; /&gt;);
 expect(wrapper.find(FontAwesomeIcon).prop(&#x27;icon&#x27;)).toEqual(someIcon);
})

// To this
test(&#x27;...&#x27;, () =&gt; {
 const { container } = render(&lt;MyComp dynamicValue=&quot;foo&quot; /&gt;);
 expect(container.firstChild).toMatchSnapshot();
})
</code></pre>
</li>
<li>
Something very similar happens if you use some library that renders canvas. There&#x27;s no way to test that from a DOM point of view, which is what RTL does.
In my case I was using <a target="_blank" rel="noopener noreferrer" href="https://www.chartjs.org/">Chart.js</a> to render some charts, so I used <a target="_blank" rel="noopener noreferrer" href="https://github.com/hustcc/jest-canvas-mock">jest-canvas-mock</a>, which exposes a method on the canvas to see which are all the events invoked from the library.
Then I used snapshots again to verify they had the expected &quot;shape&quot;.
<pre class="language-tsx"><code class="language-tsx">// I went from this...
test(&#x27;...&#x27;, () =&gt; {
 const wrapper = shallow(&lt;MyCompWithCanvas /&gt;);
 expect(wrapper.find(Chart).prop(&#x27;data&#x27;).datasets).toEqual(...);
})

// To this
test(&#x27;...&#x27;, () =&gt; {
 const { container } = render(&lt;MyCompWithCanvas /&gt;);
 const events = container.querySelector(&#x27;canvas&#x27;)?.getContext(&#x27;2d&#x27;)?.__getEvents();

 expect(events).toBeTruthy();
 expect(events).toMatchSnapshot();
})
</code></pre>
</li>
</ul>
<h3>Conclusion</h3>
For better or worst, enzyme should no longer be considered an option. If you are starting a new project or are using it on small ones, consider migrating to RTL as soon as possible.
If you are using it in bigger projects, following the process described in this article will probably help you.
In any case, you will get surprised. React testing library is a great tool and provides many benefits over enzyme.
Its main issue is that it&#x27;s not a drop-in replacement for enzyme, so you will have to change a bit your mindset.

Recently ReactJS v18 was released. I started to look into its improvements, and checked which of my projects could benefit from them. The main react-based project I maintain at the moment of writing this article is shlink-web-client, so I naturally created a new branch and started the process.

The…

My experience migrating from enzyme to react testing library

Capturing code coverage for a test suite is a very useful way to know which parts of your source code are actually getting executed by tests. This is useful not only to know if you need to add more tests to your project (in case the coverage is too low), but also, if you want to apply technics like…

Capturing remote code coverage in API tests with PHPUnit

In the last couple of days I have been playing around with the idea of combining GitHub Actions and GitHub Pages to be able to dynamically build preview environments every time a pull request is opened against a repository hosting a client-side web app.
The idea is that you can quickly preview the changes made by some contributor, without having to clone their branch and running everything locally, something specially useful for open source projects.
In this article I will explain how to set everything up, and what are some considerations and problems you may face during the process.
<h3>Enable github pages</h3>
The first thing you need to do is enable your project to publish pages on some branch. I recommend creating a new branch for this, let&#x27;s say <code>preview-env</code>, and then enabling publishing on it.
In order to do that go to your repository and then Settings -&gt; Pages, look for the Source section, and you should see something like this:
<img src="/assets/img/preview-envs/github-pages-before-enabling.png" alt="GitHub pages before enabling"/>
Click in the dropdown and select your new branch, <code>preview-env</code>. Then click Save.
<img src="/assets/img/preview-envs/github-pages-after-enabling.png" alt="GitHub pages after enabling"/>
After saving you will see a message at the top of this section telling you what&#x27;s the URL in which the pages are published. It always follows the same pattern. If your organization is <code>my-org</code> and your repository is <code>my-repo</code>, the url will be <code>https://my-org.github.io/my-repo/</code>.
<h3>Configure the workflow</h3>
Now we need to configure a workflow that will &quot;deploy&quot; the preview environment for the branch every time a new pull request is created or updated:
Let&#x27;s imagine we have a React web app that is built with node.js. The configuration could look like this.
<pre class="language-yml"><code class="language-yml"># .github/workflows/deploy-preview.yml
name: Deploy preview

on:
 pull_request: null

jobs:
 deploy:
 runs-on: ubuntu-20.04
 continue-on-error: true
 steps:
 - name: Checkout code
 uses: actions/checkout@v2
 - name: Use node.js 14.15
 uses: actions/setup-node@v1
 with:
 node-version: 14.15
 - name: Generate slug
 id: generate_slug
 run: echo &quot;##[set-output name=slug;]$(echo ${GITHUB_HEAD_REF#refs/heads/} | sed -r &#x27;s/[~\^]+//g&#x27; | sed -r &#x27;s/[^a-zA-Z0-9]+/-/g&#x27; | sed -r &#x27;s/^-+\|-+$//g&#x27; | tr A-Z a-z)&quot;
 - name: Build
 run: npm ci &amp;&amp; npm run build
 - name: Deploy
 uses: JamesIves/github-pages-deploy-action@4.1.1
 with:
 branch: preview-env
 folder: build
 target-folder: ${{ steps.generate_slug.outputs.slug }}
 - name: Publish env
 uses: marocchino/sticky-pull-request-comment@v2
 with:
 header: Preview environment
 message: |
 ## Preview environment
 https://my-org.github.io/my-repo/${{ steps.generate_slug.outputs.slug }}/
</code></pre>
<blockquote>
If you are not familiar with GitHub Actions yet, take a look at the <a target="_blank" rel="noopener noreferrer" href="https://docs.github.com/en/actions">official documentation</a>.
</blockquote>
This workflow will follow the next steps:
<ul>
<li>Checkout the code from the repository.</li>
<li>Set-up node.js 14.15</li>
<li>Based on the branch name, generate a slug that we will use to have separated deployment folders for every pull request we receive. The slug is exposed to next steps as an output.</li>
<li>Build the project. This step will obviously depend on the needs of your project.</li>
<li>Using <a target="_blank" rel="noopener noreferrer" href="https://github.com/JamesIves/github-pages-deploy-action">JamesIves/github-pages-deploy-action</a>, deploy the contents we previously built in the GitHub page, under a sub-folder matching the slug we generated a few steps above, and under the branch <code>preview-env</code> (remember we enabled GitHub pages for this branch).</li>
<li>Finally, using <a target="_blank" rel="noopener noreferrer" href="https://github.com/marocchino/sticky-pull-request-comment">marocchino/sticky-pull-request-comment</a>, post a comment in the pull request with a link to the preview environment, so that you can just click on it and see the deployment.</li>
</ul>
The steps may change depending on your needs and how you build your project. For example, I have an extra step to update a property in the <code>package.json</code> that is then used to allow serving the app in a sub-path instead of the root of the domain.
You may also not build your site with node.js, as you could be using any of the multiple existing static site generators out there, but you get the idea.
Finally, you have probably noticed the config includes <code>continue-on-error: true</code>. This will allow the pull request to be merged even if this process fails for some reason.
<h3>Considerations when using forks</h3>
While the configuration above will work perfectly when creating pull requests inside the same repository, there are some limitations when the pull request comes from a fork (which is the usual in OSS projects).
For security reasons, the <code>GITHUB_TOKEN</code> injected in those cases doesn&#x27;t have write permissions, which will make the &quot;deploy&quot; step fail.
Also, you cannot define your own token with more permissions and inject it as a secret, as the secrets are not exposed to workflows running on forks.
However, with a couple small config changes, we can work around these limitations:
<h4>Change event</h4>
The first thing we need to do is use the <code>pull_request_target</code> event instead of the <code>pull_request</code> one.
<pre class="language-diff"><code class="language-diff">on:
- pull_request: null
+ pull_request_target: null
</code></pre>
According to the documentation, this is equivalent to the <code>pull_request</code> event, but it runs in the scope of the base repository.
Thanks to this, the <code>GITHUB_TOKEN</code> will come with write permissions, and we will have access to secrets if needed.
<h4>Checkout the fork</h4>
The second thing we are going to change is that we now need to specify the repository to checkout.
In order to do that, we need to add two inputs to the &quot;Checkout code&quot; step, like this:
<pre class="language-diff"><code class="language-diff"> steps:
 - name: Checkout code
 uses: actions/checkout@v2
+ with:
+ repository: ${{ github.event.pull_request.head.repo.full_name }}
+ ref: ${{ github.event.pull_request.head.ref }}
</code></pre>
This will ensure we checkout from the fork repository, instead of the base one, which is the default, as it&#x27;s the one where the <code>pull_request_target</code> event is scoped to.
And that&#x27;s it. With these two changes you can now deploy preview environments for pull requests coming from forks.
<blockquote>
IMPORTANT! The limitations of the <code>pull_request</code> event are there for a reason. People could potentially get access to your secrets or manipulate your code. Proceed at your own risk.
</blockquote>
<h3>Other considerations</h3>
Other than the limitations for forks, there are a few other minor things to take into consideration.
<ul>
<li>Changes in GitHub Pages do not reflect immediately. It may take up to a couple of minutes for the deployment to be available, but considering you will usually not review a PR right after it has been created, this should not be a big issue.</li>
<li>As you have seen, every time a pull request is created, the deployment will generate a new folder in your GitHub Pages branch. This may result in a lot of old folders to pile-up, so you may want to set up some way to clean them up periodically or after the pull request has been merged.</li>
<li>Due to the fact that GitHub Pages only allows static pages to be served, this process cannot be used with apps that require some kind of back-end or server-side logic.</li>
<li>If your project is already using GitHub Pages for something else (serve the project&#x27;s website or docs), that may conflict with this, preventing you from having this kind of preview envs.</li>
</ul>

In the last couple of days I have been playing around with the idea of combining GitHub Actions and GitHub Pages to be able to dynamically build preview environments every time a pull request is opened against a repository hosting a client-side web app. The idea is that you can quickly preview the…

Setting-up a preview environment for your client-side apps with GitHub Actions and GitHub Pages

For a long time, I have been trying to include tests in every project in which I&#x27;ve worked on.
There are several types of automated tests (or what should actually be called <a target="_blank" rel="noopener noreferrer" href="https://abstracta.us/insights/guide-continuous-testing/automated-checks">automated checks</a>). From unit tests, integration and functional tests, to end-to-end tests.
Each one of them differs from the rest by the scope they try to cover. From small units of code which are tested completely detached from external dependencies, to a whole app which is tested as a black box like if an end consumer was using it.
I&#x27;m not going to deeply discuss the semantics behind this, or where an integration test ends and an end-to-end test starts, because it&#x27;s quite frequently a blurry line.
I want to focus on unit tests, and a frequently used practice (even in my own tests), which I have read (and felt) several times, it might not be the best approach.
<blockquote>
This article is not focused on any particular technology, since I have found this in a lot of different projects.
</blockquote>
<h3>What&#x27;s a unit test</h3>
According to <a target="_blank" rel="noopener noreferrer" href="https://en.wikipedia.org/wiki/Unit_testing">Wikipedia</a>, unit testing is a &quot;method by which individual units of source code [...] are tested to determine whether they are fit for use&quot;.
While this might look like a clear definition, it&#x27;s actually quite open because, what&#x27;s a &quot;unit&quot; in the context of unit testing?
Very often, in object oriented programming projects, people take a class as a unit to test, and create a unit test for every class. In other paradigms, like functional programming, you might consider a function as the unit to be tested, or a set of functions which you have decided to put together in a module.
This is not really important for the purpose of this article. What&#x27;s really important is to take into account that, in order to properly &quot;unit test&quot; a &quot;unit of source code&quot;, you have to do it by isolating it from any dependency of that unit.
One of the better ways to achieve this is by following the <a target="_blank" rel="noopener noreferrer" href="https://en.wikipedia.org/wiki/Dependency_inversion_principle">Dependency Injection Principle</a>. Without it you will probably end up trying to hack yourself in order to detach a &quot;unit&quot; from its dependencies.
<blockquote>
You can find other articles about <a href="/tag/dependency-injection/">Dependency Injection</a> in my blog.
</blockquote>
<h3>Replacing dependencies</h3>
A very frequent practice when unit testing a unit of source code is to replace its dependencies with <a target="_blank" rel="noopener noreferrer" href="https://en.wikipedia.org/wiki/Test_double">test doubles</a>, in order to properly isolate every unit when testing it.
Test doubles are basically objects compatible with the dependencies of the subject under test, that are created just for the purpose of the test and have some useful capabilities, like capturing how they have been called, or what should they return when called.
When you use one of those test doubles to assert how they were called as part of the test itself, you are using them as &quot;spies&quot;.
<h3>Over-trusting spies</h3>
All this introduction and contextualization had a single purpose.
I find myself (and others) in the situation in which you prepare a test double to behave in a certain way, then you call your subject under test, and then assert that your expectations on how the test double was called are correct, by spying on it.
This sometimes feels wrong, since it seems you are testing the test double/s instead of the subject under test.
I have read many times that, in a unit test, we should not actually know the internal implementation of the subject under test, but only test that, based on certain input, the expected output is returned (so, trust its public API).
However, there are cases in which some function/method does not really have any output, and we can only verify everything is going right by spying on the test doubles.
So, at the end of the day, I have mixed feelings about this practice.
<h3>Conclusion</h3>
Sadly, I cannot state a clear conclusion. This is actually an open article, and I would love to get your point of view in the form of a <a href="#comments-box">comment</a>.
It would be great to see how others face this, if you use other kinds of test doubles instead of spies, or if you are just ok with the implications.

For a long time, I have been trying to include tests in every project in which I've worked on. There are several types of automated tests (or what should actually be called automated checks). From unit tests, integration and functional tests, to end-to-end tests.

Each one of them differs from the…

Is spying on mocks a bad practice for unit tests?

I&#x27;ve been wanting to write this article for a while, but it is a subject complex to approach.
Lately I&#x27;ve had some &quot;conflicts&quot; with users in some of the open source software (OSS) projects I maintain, and I have also seen some of the people I follow on Twitter dealing with the same.
Because of that I wanted to share my point of view on what should be the attitude and considerations when using OSS.
<h3>Company vs personal</h3>
The first thing you have to take into account when using OSS, is that there are two kinds of projects which usually have different goals.
<h4>Company projects</h4>
It is very common that companies which activity is related with software or make a deep use of technology, publish their own OSS projects.
These projects are usually born from some need the company has had which is not strictly part of their domain.
Thanks to publishing these projects they can find new talent (among contributors), or position themselves in the industry.
It&#x27;s also quite common that companies provide paid services which are related with these OSS projects, like specific hostings or deployment services, or just consultancy on using them.
<h4>Personal projects</h4>
There&#x27;s also projects which are usually maintained by one person, or a very small team, during their own free time.
These projects are created by people who do it mainly because they love to program and want to share something they have done.
The goal here is to get some visibility, show some skills, learn something new and contribute to the open source community.
While the main purpose is not usually getting money, they frequently accept donations and sponsorships.
<hr/>
Now we know the two main groups of OSS projects. Sometimes we think they are the same, but company projects are usually maintained by people which is paid by a company, and do it during their working hours.
On the other hand, personal projects cannot get that much attention and resources, so they cannot progress as fast as the company ones.
<h3>Considerations</h3>
That said, when we want to use an open source project or contribute to it, there are a few things to take into account.
<h4>Always be polite</h4>
While using a project, you will probably end up finding something is not working as you expected, or you&#x27;ll develop a new need for which the project does not provide a solution.
When reporting bugs or asking for new features, always try to be polite. Provide as many details as possible, be descriptive and help maintainers reproduce the issue.
If you are asked to do some tests and get back with the result, try to find the time to do it. You may think that&#x27;s not your work, but the issue will get solved much earlier and you will avoid frustrations.
There&#x27;s a formula I like to use when reporting issues, which consists in filling this template:
<ul>
<li>I did [action].</li>
<li>I expected [behavior] to happen.</li>
<li>Instead [other_behavior] happened.</li>
</ul>
This will simplify maintainers see the user&#x27;s intention, and detect confusions which are not actually bugs. Helping the user use the tool will be easier this way.
<h4>Don&#x27;t take anything for granted</h4>
Just because you open a ticket, does not mean the team is going to work on it right away. There are several reasons that could delay it.
<ul>
<li>The project has other priorities.</li>
<li>It&#x27;s hard to reproduce.</li>
<li>There&#x27;s no one available to work on it.</li>
<li>Maintainers just want to spend their time in something else (specially in the case of personal projects).</li>
</ul>
The people working in the project is usually dealing with a much wider scope than you might think, so you have to be patient and understand this.
It could also happen that they don&#x27;t really want to maintain what you proposed, even though it&#x27;s a supper critical feature for you, but a project will never be able to cover the 100% of use cases.
<h4>Consider contributing</h4>
One of the main principles of the open source philosophy is collaboration.
If you have been using an OSS project, the best way to show some appreciation and collaborate with its continuity is by contributing to it.
There are several ways to contribute.
<ul>
<li>You could improve the documentation,</li>
<li>You could provide some PR fixing some bug or improving the code.</li>
<li>You could provide some PR with some new feature.</li>
<li>You could make some economic donation or sponsorship.</li>
</ul>
The last one is very rare, specially among individual users, but if your company is taking advantage of an OSS project, you should consider it.
For the other three cases, if there&#x27;s something you think you can help with, there&#x27;s something to take into account in relation with previous point. You should always ask first.
Maybe someone is already working on something similar, or the team has some ideas in mind that could be shared before starting any implementation, or, as I said before, maybe they just don&#x27;t want to maintain it.
If you ask first you will save yourself some time and frustrations.
<h4>Follow the project rules</h4>
All projects have rules, and I&#x27;m talking about any kind of rule. How to write issues, the code of conduct, the coding standards, the amount of people that need to approve a PR before merging it...
You have to always follow these rules. Don&#x27;t try to enforce something just because you consider it better.
If the project requires the use of spaces for indentation but you used tabs because you like them better, don&#x27;t get mad if maintainers don&#x27;t want to merge your PR.
<h4>Don&#x27;t take it personally</h4>
And finally, because of the reasons exposed in previous points, there will be decisions you don&#x27;t like.
Don&#x27;t take it personally, because it&#x27;s not in most of the cases.
Your issue could be closed because you didn&#x27;t follow the issue template, or because they asked you to check something and you didn&#x27;t give any feedback after some days.
Understand this can happen, and you can always be polite and open a discussion, but never get mad and accuse the team to be unfair or treat you in the wrong way.
<h3>Conclusion</h3>
This article describes a set of rules that should help people using OSS projects and people maintaining them to understand each other, but focusing on the former.
I will try to write something similar but focusing on how maintainers should behave. We obviously forget some times that there&#x27;s people trusting on us when using the software we write.

I've been wanting to write this article for a while, but it is a subject complex to approach. Lately I've had some "conflicts" with users in some of the open source software (OSS) projects I maintain, and I have also seen some of the people I follow on Twitter dealing with the same.

Because of that…

Considerations to properly use open source software projects

Some of you know that I work now as a full stack javascript developer, and I have interacted with a few different projects, both in front-end javascript and in nodejs. My main concern about javascript has been that, apparently, the community has not adopted one of the practices that, for me, has…

Dependency injection in nodejs projects

A couple years ago I wrote a <a href="/2016/06/12/using-service-manager-3-lazy-services-to-improve-your-php-application-performance/">post</a> about how to improve PHP applications performance by using <code>zend-servicemanager</code> lazy services.
In that article I explained how the <code>ServiceManager</code> takes advantage of the proxy design pattern to delay the creation of services, when they are marked as lazy.
That can improve performance if the object is resource consuming, but that is not the only advantage behind proxies.
<h3>A use case</h3>
Some days ago I was working on a new feature for <a target="_blank" rel="noopener noreferrer" href="https://shlink.io">Shlink</a>, an open source project I maintain.
The feature consisted on adding support to geolocate IP addresses by using <a target="_blank" rel="noopener noreferrer" href="https://dev.maxmind.com/geoip/geoip2/geolite2/">GeoLite2</a>, an IP address database which is updated every month.
They have an official <a target="_blank" rel="noopener noreferrer" href="https://github.com/maxmind/GeoIP2-php">PHP library</a>, which exposes a <code>GeoIp2\Database\Reader</code> service where you need to inject the path to the GeoLite2 library file.
Since Shlink uses the <code>zend-servicemanager</code> to manage dependency injection, I created a factory like this (these examples are pseudocode):
<pre class="language-php"><code class="language-php">&lt;?php
declare(strict_types=1);

namespace Shlinkio\Shlink\Factory;

use GeoIp2\Database\Reader;
use Interop\Container\ContainerInterface;
use Zend\ServiceManager\Factory\FactoryInterface;

class GeoLiteReaderFactory implements FactoryInterface
{
 public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
 {
 $geoLiteDbLocation = $container-&gt;get(&#x27;config&#x27;)[&#x27;geolite2&#x27;][&#x27;db_location&#x27;] ?? &#x27;&#x27;;
 return new Reader($geoLiteDbLocation);
 }
}
</code></pre>
And then registered it like this:
<pre class="language-php"><code class="language-php">&lt;?php
declare(strict_types=1);

namespace Shlinkio\Shlink\Common;

use GeoIp2\Database\Reader;
use Shlinkio\Shlink\Factory\GeoLiteReaderFactory;

return [

 &#x27;dependencies&#x27; =&gt; [
 &#x27;factories&#x27; =&gt; [
 Reader::class =&gt; GeoLiteReaderFactory::class,
 ],
 ],

];
</code></pre>
Then I registered other services which were depending on this one, and everything seemed to be ok.
<h3>The issue</h3>
My intention was to download the GeoLite2 database during Shlink&#x27;s installation.
The problem is that the <code>GeoIp2\Database\Reader</code> service throws an exception if the file you specified does not exist, and the first time Shlink is executed, it does not exist.
The way I designed my service graph was making the <code>GeoIp2\Database\Reader</code> object to be instantiated, and throw an error before being able to download the file.
I started to think on ways to workaround this issue, but none of them seemed clean enough.
Then I thought &quot;maybe I can wrap the object somehow, so that it is not created until it is going to be actually used&quot;, and then I realized that was exactly what a Proxy does, and also, that the <code>ServiceManager</code> includes its own implementation to do this.
<h3>The solution</h3>
The solution was pretty straightforward. I just had to mark the service as lazy, changing the configuration to this:
<pre class="language-php"><code class="language-php">&lt;?php
declare(strict_types=1);

namespace Shlinkio\Shlink\Common;

use GeoIp2\Database\Reader;
use Shlinkio\Shlink\Factory\GeoLiteReaderFactory;
use Zend\ServiceManager\Proxy\LazyServiceFactory;

return [

 &#x27;dependencies&#x27; =&gt; [
 &#x27;factories&#x27; =&gt; [
 Reader::class =&gt; GeoLiteReaderFactory::class,
 ],
 ],
 
 &#x27;delegators&#x27; =&gt; [
 Reader::class =&gt; [
 LazyServiceFactory::class,
 ],
 ],
 
 &#x27;lazy_services&#x27; =&gt; [
 &#x27;class_map&#x27; =&gt; [
 Reader::class =&gt; Reader::class,
 ],
 &#x27;proxies_target_dir&#x27; =&gt; &#x27;data/proxies&#x27;,
 &#x27;proxies_namespace&#x27; =&gt; &#x27;ShlinkProxy&#x27;,
 &#x27;write_proxy_files&#x27; =&gt; true,
 ],

];
</code></pre>
And that&#x27;s it. No further code changes were needed, only configuration.
With this change, the constructor of the <code>GeoIp2\Database\Reader</code> is no longer run until the object is going to be actually used, which allows Shlink to be installed, and the database file to be downloaded.
<blockquote>
If you want to more deeply understand what the new config actually means, it is explained in detail in my <a href="/2016/06/12/using-service-manager-3-lazy-services-to-improve-your-php-application-performance/">previous article</a> about lazy services.
</blockquote>
<h3>Conclusion</h3>
With this article I just wanted to share how to solve a specific issue introduced by third party code, where you don&#x27;t have the &quot;power&quot; to change the implementation.
I also wanted to expose a real use case, which will probably remind you to some real situation in which you have faced a similar problem in the past.

A couple years ago I wrote a post about how to improve PHP applications performance by using zend-servicemanager lazy services. In that article I explained how the ServiceManager takes advantage of the proxy design pattern to delay the creation of services, when they are marked as lazy.

That can…

Delay constructor execution by using ServiceManager lazy services

I have written a lot of posts about Zend Framework in general and Zend Expressive in particular, but I have noticed that I have never talked about one of the things that, from my point of view, makes Expressive so game-changing, Interoperability.
<h3>Some context</h3>
In the past, PHP frameworks used to be very big libraries, which tried to provide solutions to any possible problem in order to retain users.
At that time, you had to decide which framework you wanted to use, by weighing pros and cons. People ended up saying &quot;I prefer framework foo, because it has a better templating system&quot;, &quot;ok, but framework bar has a better performance and its dependency injection approach is delightful&quot;.
It wasn&#x27;t easy to pick the best part of each framework (or the parts you liked the most) and be able to use them in the same project. You couldn&#x27;t just take the templating system from foo and make it work with the dependency injection approach from bar.
Because of this, the <a target="_blank" rel="noopener noreferrer" href="https://www.php-fig.org/">PHP Framework Interop Group</a> was born (PHP-FIG from now on). Its goal was to define standard recommendations that frameworks and libraries could adhere to.
At some point this would mean that frameworks would use compatible APIs in their different components and people would be able to easily change one specific component by another.
<h3>Expressive&#x27;s interoperability</h3>
Mostly all frameworks which are part of the PHP-FIG have more or less adopted these standard recommendations. If you have been working with PHP in the last 3-4 years, you know it is now much easier to &quot;mix&quot; libraries and frameworks in the same project.
However, the one which has been capable of making interoperability part of its essence is <a target="_blank" rel="noopener noreferrer" href="https://docs.zendframework.com/zend-expressive/">Zend Expressive</a> (probably because it was born in that period and interoperability was one of its main design goals).
Expressive itself does not provide solutions to almost anything. Instead, it relies in a series of interfaces and abstractions in order to get everything working.
Some of those abstractions are PHP Standard Recommendations (PSRs) from the PHP-FIG.
<ul>
<li>It is a middleware-based framework, so it expects your middlewares and actions (request handlers) to implement <a target="_blank" rel="noopener noreferrer" href="https://www.php-fig.org/psr/psr-15/">PSR-15</a> interfaces. This way, your own code is not coupled with Expressive at all.</li>
<li>In order to dispatch this middlewares they use a middleware dispatcher, <a target="_blank" rel="noopener noreferrer" href="https://docs.zendframework.com/zend-stratigility/">Zend Stratigility</a> in this case, which also implements PSR-15&#x27;s request handler interface.</li>
<li>It is also a web framework, so it needs to dispatch HTTP requests. For this, it expects you to include a library implementing <a target="_blank" rel="noopener noreferrer" href="https://www.php-fig.org/psr/psr-7/">PSR-7</a>. They provide one implementation, <a target="_blank" rel="noopener noreferrer" href="https://docs.zendframework.com/zend-diactoros/">Zend Diactoros</a>, but you can use whatever you want.</li>
<li>Expressive promotes Dependency Injection, so it expects a dependency injection container to be used. Once again, they expect any container implementing <a target="_blank" rel="noopener noreferrer" href="https://www.php-fig.org/psr/psr-11/">PSR-11</a>, so you can use the container of your choice and everything will work.</li>
</ul>
The PHP-FIG still has some work to do in different areas. For those cases in which there&#x27;s no standard recommendation, Zend&#x27;s team has defined a few own interfaces and abstractions Expressive relies on in order to ease decoupling and extendability.
<ul>
<li>Routing: You can pick one of provided implementations or define your own (<a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya/expressive-slim-router">I&#x27;ve done it</a> and it wasn&#x27;t that hard)</li>
<li>Templating: If you need to render templates, expressive has official support for three templating systems, but as in previous case, you can use other engines with a minimal effort. 
However, you are not forced to use a templating system if you don&#x27;t need it, which is great.</li>
<li>Error handling: You shouldn&#x27;t handle errors the same way in production and development environments. Expressive&#x27;s abstractions let you use different approaches, with great integration to use <a target="_blank" rel="noopener noreferrer" href="http://filp.github.io/whoops/">Whoops</a> in development, but you could use something like <a target="_blank" rel="noopener noreferrer" href="https://tracy.nette.org/en/">Tracy</a> too.</li>
</ul>
All of these abstractions are defined in separated packages, so in the future, if the PHP-FIG accepts a PSR for any of these things, Zend Expressive will probably start supporting them and drop these packages&#x27; interfaces as far as possible.
<h3>Expressive&#x27;s extendability</h3>
There are a lot of things a real project needs which have been left out of expressive&#x27;s scope, which is in fact good.
You will probably need some way to handle configuration. Expressive doesn&#x27;t tell you what to use, because usually config is consumed before the request is even dispatched, so there&#x27;s no need for any kind of integration.
You will also need something to connect to a database, or consume external services. Once again, use whatever you want.
If you need to be able to run your app from the command line, expressive and the HTTP layer won&#x27;t even come in place. For that purpose, Zend&#x27;s team recommends using <a target="_blank" rel="noopener noreferrer" href="http://symfony.com/doc/current/components/console.html">symfony/console</a> these days. In fact, there are a few CLI utilities for expressive which have been built with that component, like <a target="_blank" rel="noopener noreferrer" href="https://github.com/zendframework/zend-expressive-tooling">zend-expressive-tooling</a>.
Of course, all of this flexibility is great for experienced developers, but newcomers need a little bit of help to begin with. That&#x27;s why a <a target="_blank" rel="noopener noreferrer" href="https://github.com/zendframework/zend-expressive-skeleton">skeleton project</a> was created.
The skeleton is installed using an interactive process which let&#x27;s you choose the different components to be used, and the project approach you want to take.
This wide range focus makes expressive fit any project. Also, despite the fact that it can be considered a microframework, I can tell you it <a href="/2016/07/21/project-scalability-with-zend-expressive/">scales quite well</a>.
<h3>Proof of concept</h3>
Ok, perfect, interoperability runs in expressive veins, but I don&#x27;t want you to just take my word. That&#x27;s why I have built an example project where I use a variety of libraries and components for every task.
In order to build the project, I have used the skeleton mentioned before, and then tweaked it a little bit. You can find it here: <a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya-blog/expressive-interoperability-proof-of-concept">https://github.com/acelaya-blog/expressive-interoperability-proof-of-concept</a>
These are the components I have used:
<ul>
<li>DI Container: <a target="_blank" rel="noopener noreferrer" href="http://php-di.org/">PHP-DI</a></li>
<li>Router: <a target="_blank" rel="noopener noreferrer" href="https://github.com/acelaya/expressive-slim-router">Slim framework v2</a></li>
<li>Template renderer: <a target="_blank" rel="noopener noreferrer" href="https://twig.symfony.com/">Twig</a></li>
<li>HTTP abstraction: <a target="_blank" rel="noopener noreferrer" href="https://github.com/guzzle/psr7">Guzzle PSR-7 HTTP message library</a></li>
<li>Error handling: <a target="_blank" rel="noopener noreferrer" href="http://filp.github.io/whoops/">Whoops</a></li>
</ul>
The result is that very few of the code is actually from <code>Zend</code>&#x27;s namespace.
The project includes the instructions to run it and see how everything is in fact working. It also includes one option in the menu to see an error page.
<h3>Conclusion</h3>
From my point of view, full-stack and coupled frameworks are something from the past. I like to be free to choose the tools I want to use in a project for every task, and to be able to use the best ones or the ones I like the most.
For me, it makes no sense these days to ask &quot;What PHP framework do you use?&quot;, because thanks to the PHP-FIG and initiatives like Expressive it&#x27;s more and more hard to answer.
Of course, if the full-stack approach is the one that fits you and makes you be more productive, I&#x27;m nobody to say otherwise :-)

I have written a lot of posts about Zend Framework in general and Zend Expressive in particular, but I have noticed that I have never talked about one of the things that, from my point of view, makes Expressive so game-changing, Interoperability. Some context

In the past, PHP frameworks used to be…

Alejandro Celaya | Blog

Software development, agile methodologies and open source software.

Is spying on mocks a bad practice for unit tests?

Considerations to properly use open source software projects

Dependency injection in nodejs projects

Delay constructor execution by using ServiceManager lazy services

Demonstrating the interoperability and decoupling of Zend Expressive