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Create a test DSL to test the DSL

Yesterday I asked how we can efficiently test this piece of code:

specification @vacations:
	requires @scheduling_work
	requires @external_connections

Trying to test that with C# code resulted in 1500% disparity in number of lines of code. Obviously a different approach was needed. Since I am in a DSL state of mind, I wrote a test DSL for this:

script "quotes/simple.boo"

with @vacations:
	should_require @scheduling_work
	should_require @external_connections	

with @scheduling_work:
	should_have_no_requirements

I like this.

You can take a look at the code here.

Print | posted on Wednesday, May 21, 2008 12:21 PM

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# re: Create a test DSL to test the DSL 5/21/2008 2:31 PM James Gregory

Nice, but how are you going to test that the testing DSL works? ;)

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 re: Create a test DSL to test the DSL 5/21/2008 2:33 PM Dan

Are you going to test this new DSL with itself?

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# re: Create a test DSL to test the DSL 5/21/2008 2:37 PM Ayende Rahien

Quis custodiet ipsos custodes?

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# re: Create a test DSL to test the DSL 5/21/2008 3:34 PM Benny Thomas

Its kind of nice. You have to write a TestDSL engine to test your dependencies on your DSL script.

What happens if you shuffle the should_require statements?

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# re: Create a test DSL to test the DSL 5/21/2008 3:55 PM Ayende Rahien

Nothing much, there isn't an order dependency in the implementation that I wrote for them

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 re: Create a test DSL to test the DSL 5/21/2008 4:16 PM Aaron Jensen

That's a lot more than a 1500% disparity now (yes I know it's just framework code and its not repeated, I'm just being pedantic). I think writing another full on boo dsl for testing something so trivial is a bit extreme. Why not just a base test class? Or some extension methods?

"quotes/simple.boo".With("vacations").ShouldRequire("scheduling_work")
"quotes/simple.boo".With("vacations").ShouldRequire("external_connections")
"quotes/simple.boo".With("scheduling_work").ShouldHaveNoRequirements()

Totally breaks AAA, but that's easily fixable.

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# re: Create a test DSL to test the DSL 5/21/2008 5:51 PM Rob

Creating testing DSL's is something I just started doing and it has been awesome. I found that there are certain patterns that one tests repeatedly, so this can help.

 re: Create a test DSL to test the DSL 5/21/2008 8:33 PM Max

You aren't testing the code, you're writing the same program twice :-)

Is this really useful?

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# re: Create a test DSL to test the DSL 5/21/2008 8:48 PM Ayende Rahien

Max,
Try this, then:

Script:

specification @vacations:
requires @scheduling_work
requires @external_connections if UserCount > 50

Tests:

with @vacations, Users(51):
should_require @scheduling_work
should_require @external_connections

with @vacations, Users(49):
should_require @scheduling_work
should_not_require @external_connections

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# re: Create a test DSL to test the DSL 5/21/2008 9:07 PM Ayende Rahien

Aaron,
That is because you consider only the code that you have here. Consider the case of a useful DSL where you have plenty of scripts that you want to test.
Since the cost of writing a DSL is very low, I see this is as a huge benefit.

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 re: Create a test DSL to test the DSL 5/21/2008 10:18 PM vedic

yes. that also. 1500% is exactly... well... more or less more than 90% less time.
i like this too.

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