This package implements tryTestQ and related helpers in order to better test Template Haskell code. It supports returning the actual error message that recover doesn’t currently return as well as mocking out Q actions, so that you can run Template Haskell code at runtime.
Usage
-- e.g. $(showInfo "Bool") generates a string corresponding
-- to the reify `Info` for `Bool`.
showInfo :: String -> Q Exp
showInfo s = do
mName <- lookupTypeName s
case mName of
Nothing -> fail $ "Unknown type: " ++ s
Just name -> do
info <- reify name
lift $ show info
-- example using tasty-hunit
main :: IO ()
main = defaultMain $ testGroup "my-project"
[ testCase "showInfo unmocked" $(do
result1 <- tryTestQ unmockedState $ showInfo "Bool"
runIO $ isRight result1 @? ("Unexpected error: " ++ show result1)
result2 <- tryTestQ unmockedState $ showInfo "Foo"
runIO $ result2 @?= Left "Unknown type: Foo"
[| return () |]
)
, testCase "showInfo mocked success" $ do
let state = QState
{ mode = MockQ
, knownNames = [("Bool", ''Bool)]
, reifyInfo = $(loadNames [''Bool])
}
let result1 = tryTestQ state $ showInfo "Bool"
isRight result1 @? ("Unexpected error: " ++ show result1)
let result2 = tryTestQ state $ showInfo "Foo"
result2 @?= Left "Unknown type: Foo"
]
Changes
Upcoming
1.1.1
Support GHC 9.2
1.1.0
Rewrite with runTestQ, allowing for both recoverable Q actions and mocked Q actions in IO.
The previous tryQ' function can be reimplemented as:
tryQ' :: Q a -> Q (Either String a)
tryQ' = tryTestQ unmockedState
with the other helpers defined as before, using tryQ'.