What is the best way to define test specs in JSON using a Ruby harness? - ruby

Question

I've got an interesting conundrum. I'm in the midst of developing a library to parse PSDs in Ruby. Also, a buddy is simultaneously working on a library to parse PSDs in JavaScript. We would like to share the same unit tests via a git submodule.
We've decided to use a simple JSON DSL to define each test. A single test might look like:
{
"_name": "Layer should render out",
"_file": "test/fixtures/layer_out.psd",
"_exports_to": "test/controls/layer_out_control.png"
}
So, now it's up to us to build the appropriate test harnesses to translate the JSON into the appropriate native unit tests. I've been using MiniTest to get myself up to speed, but I'm running into a few walls.
Here's what I've got so far. The test harness is named TargetPractice for the time being:
# run_target_practice.rb
require 'target_practice'
TargetPractice.new(:test) do |test|
test.pattern = "test/**/*.json"
end
and
# psd_test.rb
class PSDTest < MiniTest::Unit::TestCase
attr_accessor :data
def tests_against_data
# do some assertions
end
end
and
# target_practice.rb
class TargetPractice
attr_accessor :libs, :pattern
def initialize(sym)
#libs = []
#pattern = ""
yield self
run_tests
end
def run_tests
FileList[#pattern].to_a.each do |file|
test_data = JSON.parse(File.open(file).read)
test = PSDTest.new(test_data["_name"]) do |t|
t.data = test_data
end
end
end
end
Unfortunately, I'm having trouble getting a yield in the initialize to stick in my PSDTest class. Also, it appears that a test will run immediately on initialization.
I would like to dynamically create a few MiniTest::Unit::TestCase objects, set their appropriate data properties and then run the tests. Any pointers are appreciated!

Answer 1

I think you are overcomplicating things a bit here. What you need is a parameterized test, which is pretty trivial to implement using mintest/spec:
describe "PSD converter" do
def self.tests(pattern = 'test/**/*.json')
FileList[pattern].map{|file| JSON.parse(File.read(file))}
end
tests.each do |test|
it "satisfies test: " + test["_name"] do
# some assertions using test["_file"] and test["_exports_to"]
end
end
end