An idea. You can make a type:
data TestContains = TestContains Tweet TweetSet
and the make an Arbitrary instance for it. When you do
a recursove call you have three different tweets one new tweet
and two from the sub-calls. Then you can place one of them in the
result. In the end you will have a random TweetSet with some value from it.
Here is a scratch of the implementation:
instance Arbitrary TestContains where
arbitrary = sized set'
where set' 0 = mkSingleTweet $ (arbitrary :: Tweet)
set' n = do
t0 - arbitrary :: Tweet
TestContains t1 ts1 - subTweets
TestContains t2 ts2 - subTweets
t - oneof [t0, t1, t2]
return $ TestContains t $ TweetSet t0 ts1 ts2
subTweets = set' (n `div` 2)
2012/11/21 gra...@fatlazycat.com
I have
data Tweet = Tweet {
user :: String,
text :: String,
retweets :: Double
} deriving (Show)
data TweetSet = NoTweets | SomeTweets Tweet TweetSet TweetSet
and trying to create some generators for testing, with
instance Arbitrary Tweet where
arbitrary = liftM3 Tweet arbitrary arbitrary arbitrary
instance Arbitrary TweetSet where
arbitrary = sized set'
where set' 0 = return NoTweets
set' n | n0 = oneof[return NoTweets, liftM3 SomeTweets
arbitrary subTweets subTweets]
where subTweets = set' (n `div` 2)
but wondering how I would go about generating a random TweetSet that
contains a known random Tweet I later have reference to and I would also
assume the known Tweet to be placed randomly.
Then I could test a contains function.
Thanks
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