[rspec-users] Best practices to managing RSpec code for very large projects?
J. B. Rainsberger
jbrainsberger at gmail.com
Thu Feb 4 09:09:45 EST 2010
On Thu, Feb 4, 2010 at 00:12, David Mitchell <monch1962 at gmail.com> wrote:
> What is the 'best practice' way to structure RSpec code and documentation
> when testing a very large project, where the RSpec code base has to be
> maintained and extended over a long period?
I don't mean to be glib, but my blink reaction is that there's nothing
different between maintaining a large suite of RSpec examples and any
other large code base. I think all the design principles for large
production code bases apply to large suites of RSpec examples.
> Over the life of the project, there's been a number of people writing RSpec
> tests without any overriding guidance on things like:
> - appropriate naming of helper functions
> - use of private vs. protected vs. public methods to only expose
> functionality as required
> - ensuring the scope of code is managed correctly (e.g. code for testing
> databases should probably be held in a module named 'Database')
> - documentation, in any form e.g. what a helper function does, what its side
> effects are, coverage of modules & how to extend them, ...
> - use of 'raise' and 'warn' to highlight problems
> - etc., etc.
I truly think the Four Elements of Simple Deign would help all those.
> As a result, what exists now is basically a huge mess. For example, we've
> got multiple helper functions named identically, that serve very different
> purposes e.g. 'it_should_be_nil', with one doing a string comparison,
> another covering the number of records returned in a database cursor, and so
> on. The scope of these functions is such that they're accessible from all
> the 'wrong' places, so it's quite possible that the wrong helper function
> could accidentally be referenced at any point and quite difficult to
> identify which one of several identically-named helper functions is going to
> be executed at any given point.
> Aside from some serious therapy, what I'm looking for is some sort of 'best
> practices' documentation covering how to use RSpec to create *and maintain*
> a very large population of test cases over an extended period of time. If I
> can get that, then I can at least start working in the right direction to
> ensure the problem doesn't get any worse, and then start fixing what exists
> now. Issues that are biting me right now include:
> - how to structure a hierarchy of RSpec modules to cover both unit- and
> functional-test requirements. For unit-testing, it seems to make sense to
> create a hierarchy along infrastructure lines, so there might be a module
> named 'Database' that includes all the generic database test functions (e.g.
> check table names, field names, field definitions, constraints, triggers,
> ... are all defined correctly), that is subclassed into distinct modules for
> each database instance being tested. However, for functional-testing, it
> seems to make more sense to create a hierarchy along business process lines,
> so that helper functions covering a particular set of business functionality
> are bundled together. Given you'll probably want to use a lot of the same
> methods in both your functional- and unit-test code, what's the best way to
> structure this hierarchy?
> - use of modules/namespaces to achieve sensible isolation of functionality
> (e.g. the 'it_should_be_nil' problem described above), while still having
> the code referencing functions in modules being readable
> - documentation requirements when building/maintaining a large RSpec test
> suite over an extended period of time, so that you don't wind up relying
> exclusively on knowledge held in the heads of key people, and new people can
> be brought up to date on "how it all hangs together" relatively quickly
> If anyone can point me to useful reference material along these lines, I'd
> greatly appreciate it.
Have you read Feathers' "Working Effectively with Legacy Code"? I
think that might help you recover from this mess.
As for some Novice Rules to organize your examples, I recommend this:
* Keep offline and online examples separate, so I can run all the
examples that require expensive external resources separately from the
one that don't. I use separate source folders for this.
* Move test data creation into a folder like Rails' relatively new
spec/support folder. Over time, introduce libraries like FactoryGirl
to reduce the amount of code you write to create test data.
* Refactor test facilities, like custom matchers, to spec/support to
make them available to everyone.
To fix the underlying problem, I recommend something bigger: invite
your teams to spend 90 minutes, once per week, putting their examples
up on a projector and play "What's not to like about this code?" Start
refactoring it there and then. Doing this every week helps teams
converge on their understanding of "good enough design" as well as
helps them share information about how they organize their examples
and the code that supports them. It simply sounds like your
programmers don't discuss these ideas with each other enough, or if
they do, they don't agree enough. Whatever changes you make to the
code base don't matter if you don't also do something like this.
J. B. (Joe) Rainsberger :: http://www.jbrains.ca ::
Diaspar Software Services :: http://www.diasparsoftware.com
Author, JUnit Recipes
2005 Gordon Pask Award for contribution to Agile practice :: Agile
2010: Learn. Practice. Explore.
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