Category: ruby

EphemeralModel, for Rails 2.2.2 form validation without a DB table

I recently upgraded WhatYouAte.com to Rails 2.2.2. I had been using advice from the Rails Wiki’s HowToUseValidationsWithoutExtendingActiveRecord page. I was using a class based on the RailsWeenie code (that site is down now) and it stopped working. Here’s a new replacement hack that works almost identically.
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Rakefile snippet to run Rails’ rake:stats in a plain old gem

I’ve been moving a bunch of utility code out of a medium sized project (>10KLOC) to make it easier to test. I started by trying to make a set of plugins, but inter-plugin dependency management is basically nonexistent, and now that Rails supports explicit Gem dependencies, I decided to make them gems.

I’m happy I chose to make them gems, but I miss some of the stuff you get in a Rails project. In particular I wanted ‘rake:stats’, so I can update my estimation spreadsheet which is now almost 9 months old. I need the stats for each gem in addition to the main Rails project, in order to compare this to prior figures from the Rails project before I split it up.

So, here is the Rakefile snippet that I added, which adds the rake:stats task into a regular gem. If you don’t have the Rails gem installed, it will fail gracefully, without breaking your whole gem. So you need not make your teeny little gem depend on all of Rails being installed on every machine where your gem needs to go. Just install Rails whereever you want to run stats, which is probably already the case on your development machine.
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Making Rcov measure your whole Rails app, even if tests miss entire source files

I’ve seen a few Rake tasks for Rcov that work OK, but which fail in an interesting way (if you care about coverage): they give your coverage metrics an unexpected boost if you have 0% coverage in one or more source files.

Huh? Exactly. If you have 500 source files, and your test suite only requires one of them, then you get a free ride on those 499 files that have 0% coverage. Theoretically you could get 100% coverage in your report even though 499 source files are not touched at all. D’oh!
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Rails snippet: require app files only once

Ruby’s Kernel.require method will re-require the same source file if you pass it differing arguments that point to the same file. It doesn’t use File.expand_path to make sure it hasn’t already loaded the same file before. This can cause problems if you’re using constants or doing one-time initialization in a source file that’s getting loaded multiple times for one reason; you’ll need to add a wrapper that prevents re-entry.

If this annoys you as much as it does me (why should my application code include workarounds for what I regard to be a Ruby bug?), add this snippet to your config/environment.rb (pre Rails 2.0) or config/preinitializer.rb (Rails 2.0 or later).
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