Does your code have comments? Sometimes they’re helpful. But most of the time…
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As Jeff Atwood explains, code tells you how, comments tell you why. A well-placed code comment is a level above the code itself, explaining why something is written the way it is. But! We can express most comments as code, using well-named identifiers. The Refactoring book calls this Introduce Explaining Variable. Martin Fowler has since renamed that refactoring to Extract Variable to help folks find it in their IDEs.
It’s time for a quick exercise in code smells!
How many code smells do you see below?
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When I was first learning TDD, I’d try to get to the First Step (a failing test) by writing a fully-formed test. But it often took a lot fiddling to get that test to run and fail. Sometimes this was because the production code took several steps to set up. Sometimes it was because the test code wasn’t right.
One of the tricky parts of TDD is that we’re creating two streams of code in parallel: the test code, and the production code. Two things changing at the same time… that’s a hard thing to keep in your head!
Happy new year! It seems like good time for a Quality Coding retrospective. I also want to share some goals for 2018.
…Did someone say, “Are you writing a book?”
We’ve looked at ways to mock methods in Swift. But what about standalone functions? Is there a way to mock them as well?
Yes! Not only can we mock Swift standalone functions, but we can do it without changing the call sites.
We get feedback from the compiler. We get feedback from Test-Driven Development. But what sources of feedback lie in between?
This is where linters come in. A linter goes beyond “Does the code compile?” A linter answers questions like, “Is the code idiomatic? Is it stylistically clean? Are there any red flags?”
A paper published in 2013 about Test-Driven Development included the following diagram. Unfortunately, it gets some things wrong:
A tweet from Nat Pryce sparked discussion:
Grumpy request to academics: if you're going to publish ideas about how to improve TDD, get the original process right! pic.twitter.com/FaSU8CF6ol
— Nat Pryce (@natpryce) September 7, 2017
First, let me say I’m happy to see more studies on TDD. The thrust of this particular study is that TDD can be soft on negative tests. That is, maybe the code works for good data, but it’ll break on bad data.
TDD is a development discipline, so I’m all for learning more from traditional testing disciplines. I certainly don’t want to discourage folks from doing studies and writing papers.
But. Let’s first make sure we’re doing proper TDD, shall we? Otherwise any studies, especially studies about efficacy, may be flawed.
Do you enjoy conferences and workshops? Here’s my conference schedule for this fall:
The “Single Responsibility Principle” (SRP) sounds so noble. But I’m afraid it’s misunderstood and misapplied. Ask your teammates: “What is the Single Responsibility Principle?” Go ahead, ask them. Then ask if the SRP is a good thing or a bad thing. I’d bet many of them will say something like this: “In principle, it’s a good idea. But in practice, it’s overkill.”
On Twitter, Chris Eidhof pointed to an example of taking the Single Responsibility Principle too far. Specifically, Chris was unhappy with the argument that Singletons violate the SRP because, besides their main responsibility, they also manage their own life cycle:
This argument against singletons made me cringe (specifically, the SRP point): https://t.co/C9wVVnqHFs
— Chris (@chriseidhof) June 29, 2017
This led to a lively discussion. Many reacted against “over-architecture.” No doubt they experienced fragmented code that grew from over-zealous attempts at SRP.
I think that SRP isn’t just over-applied. It’s fundamentally misunderstood, even misquoted. The repeated misquotes perpetuate that misunderstanding.
Let’s see if we can clear things up, and point to a better way.
Those of you who are regular visitors to qualitycoding.org may have already read Jon’s article outlining the life cycle of XCTestCase objects during the execution of a test suite. If you haven’t, or you want to refresh your memory, take a moment to read the original article.
Jon discusses the importance of the setUp and tearDown methods. And, more specifically, why we should be deallocating our properties in the tearDown method.
Writing a tear down method is one of those repetitive tasks. It follows a specific pattern: all properties should be set to nil. It doesn’t really require any brain power. It’s just one of those annoying tasks that you have to remember to do when writing a test.
It’s tasks like this that should be automated. And now with the Swift tear down inspection AppCode plugin, we can.