Re: [Haskell] ANN: SmallCheck 0.1

[Colin Runciman]

Don,

Let's run QuickCheck (check) head to head with SmallCheck (scheck): 
...
lambdabot scheck \s - not (null s) == minimum (s :: [Int]) == (last . 
 sort) s
  Failed test no. 10. Test values follow.: [-1,-1,-1,-1,-1,-1,-1,0]

lambdabot check \s - not (null s) == minimum (s :: [Int]) == (last . 
 sort) s
 Falsifiable, after 1 tests: [2,1]
  

So your plugin  is based on depthCheck 8, not the iterative deepening
of smallCheck; otherwise smallCheck would report [-1,0] as the first
failure.

I'll add a 'batch' version of iterative deepening.

One thing needed for online use: some more instances for the various numeric
types might be useful, Float, Double, Ratio, Complex etc.
  

Fair point.  I admit that I rarely use numbers other than the non-negative
integers when programming. Even deciding to include -1 in the default Int
series was a trip into an alien world. :-)  

I'll add some simple default instances for other numeric types used by
the more arithmetically adventurous.

Colin

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[Haskell] ANN: SmallCheck 0.1

[Colin Runciman]

SmallCheck: another lightweight testing library in Haskell.

Folk-law: if there is any case in which a program fails, there is almost
always a simple one.

SmallCheck is similar to QuickCheck (Claessen and Hughes 2000-)
but instead of a sample of randomly generated values, SmallCheck
tests properties for all the finitely many values up to some depth,
progressively increasing the depth used.  For data values, depth means
depth of construction.  For functional values, it is a measure combining
the depth to which arguments may be evaluated and the depth of possible
results.

Other possible sales pitches:
* write test generators for your own types more easily
* be sure any counter-examples found are minimal
* write properties using existentials as well as universals
* establish complete coverage of a defined test-space
* display counter-examples of functional type

A new version of SmallCheck can be obtained from:
http://www.cs.york.ac.uk/fp/smallcheck0.1.tar
The differences from 0.0 are two fixes (space-fault, output buffering),
an 'unsafe' but sometimes useful Testable (IO a) instance and additional
examples.

Comments and suggestions welcome.

Colin R

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Re: [Haskell] ANN: SmallCheck 0.1

[Donald Bruce Stewart]

colin:
 SmallCheck: another lightweight testing library in Haskell.
 
 Folk-law: if there is any case in which a program fails, there is almost
 always a simple one.
 
 SmallCheck is similar to QuickCheck (Claessen and Hughes 2000-)
 but instead of a sample of randomly generated values, SmallCheck
 tests properties for all the finitely many values up to some depth,
 progressively increasing the depth used.  For data values, depth means
 depth of construction.  For functional values, it is a measure combining
 the depth to which arguments may be evaluated and the depth of possible
 results.
 
 Other possible sales pitches:
 * write test generators for your own types more easily
 * be sure any counter-examples found are minimal
 * write properties using existentials as well as universals
 * establish complete coverage of a defined test-space
 * display counter-examples of functional type
 
 A new version of SmallCheck can be obtained from:
 http://www.cs.york.ac.uk/fp/smallcheck0.1.tar
 The differences from 0.0 are two fixes (space-fault, output buffering),
 an 'unsafe' but sometimes useful Testable (IO a) instance and additional
 examples.
 
 Comments and suggestions welcome.

I've written a lambdabot plugin for SmallCheck, to go with the existing
one for QuickCheck. It's running on #haskell now (after removing that
pesky Testable IO instance (not good for security...).

Let's run QuickCheck (check) head to head with SmallCheck (scheck): 

$ ./lambdabot
Initialising plugins . done.

lambdabot check True
 OK, passed 500 tests.

lambdabot scheck True
 Completed 1 test(s) without failure.

lambdabot check \s - (s :: [Int]) == (reverse . reverse) s
 OK, passed 500 tests.

lambdabot scheck \s - (s :: [Int]) == (reverse . reverse) s
 Completed 623530 test(s) without failure.

lambdabot check \s - not (null s) == minimum (s :: [Int]) == (head . 
sort) s
 OK, passed 500 tests.

lambdabot scheck \s - not (null s) == minimum (s :: [Int]) == (head . 
sort) s
 Completed 623530 test(s) without failure.  But 1 did not meet == 
condition.

lambdabot scheck \s - not (null s) == minimum (s :: [Int]) == (last . 
sort) s
  Failed test no. 10. Test values follow.: [-1,-1,-1,-1,-1,-1,-1,0]

lambdabot check \s - not (null s) == minimum (s :: [Int]) == (last . 
sort) s
 Falsifiable, after 1 tests: [2,1]

One thing needed for online use: some more instances for the various numeric
types might be useful, Float, Double, Ratio, Complex etc.

-- Don
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