tasty-autocollect
Autocollection of tasty tests.
https://github.com/brandonchinn178/tasty-autocollect#readme
Version on this page: | 0.4.1@rev:1 |
LTS Haskell 22.33: | 0.4.3 |
Stackage Nightly 2024-09-07: | 0.4.3 |
Latest on Hackage: | 0.4.3 |
tasty-autocollect-0.4.1@sha256:011ec88673459f4b313dcb1a0930aa4599ff4b9abd20303d79bf4f8139c9236f,4684
Module documentation for 0.4.1
- Test
- Test.Tasty
- Test.Tasty.AutoCollect
- Test.Tasty.Ext
- Test.Tasty
tasty-autocollect
A preprocessor/compiler plugin that will automatically collect Tasty tests and generate a main file to run all the tests.
Design goals:
- Don’t use any weird syntax so that syntax highlighters, linters, and formatters still work
- Avoid universally exporting the whole test module, so that GHC can warn about unused test helpers
- Support arbitrary test functions (e.g. user-defined test helpers or third-party tasty libraries)
- Minimal dependencies
- Only uses boot libraries, with two exceptions:
tasty
+tasty-expected-failure
- Only uses boot libraries, with two exceptions:
Quickstart
-
Add the following to your
package.yaml
or.cabal
file:tests: my-library-tests: ghc-options: -F -pgmF=tasty-autocollect build-tools: - tasty-autocollect:tasty-autocollect ... dependencies: - tasty-autocollect - ...
test-suite my-library-tests ghc-options: -F -pgmF=tasty-autocollect build-tool-depends: tasty-autocollect:tasty-autocollect ... build-depends: tasty-autocollect ...
-
Write your main file to contain just:
{- AUTOCOLLECT.MAIN -}
-
Write your tests:
{- AUTOCOLLECT.TEST -} module MyTest ( {- AUTOCOLLECT.TEST.export -} ) where import Test.Tasty.Golden import Test.Tasty.HUnit import Test.Tasty.QuickCheck test = testCase "Addition" $ do 1 + 1 @?= (2 :: Int) 2 + 2 @?= (4 :: Int) -- See the "Integration with QuickCheck/SmallCheck/etc." section -- for a more seamless integration test = testProperty "reverse . reverse === id" $ \xs -> (reverse . reverse) xs === id (xs :: [Int]) test = goldenVsString "Example golden test" "test/golden/example.golden" $ pure "example" test = testGroup "manually defining a test group" [ testCase "some test" $ pure () , testCase "some other test" $ pure () ]
Features
In addition to automatically collecting tests, this library also provides some additional functionality out-of-the-box, to make writing + managing tests a seamless experience.
Integration with QuickCheck/SmallCheck/etc.
Property test frameworks like QuickCheck or SmallCheck work better when defining the types of arguments instead of using lambdas. So there’s a special syntax for defining properties:
test_prop :: [Int] -> Property
test_prop "reverse . reverse === id" xs = (reverse . reverse) xs === id xs
This will be rewritten to the equivalent of:
test =
testProperty
"reverse . reverse === id"
( (\xs -> (reverse . reverse) xs === id xs)
:: [Int] -> Property
)
Marking tests as “TODO”
If you’re of the Test Driven Development (TDD) mentality, you might want to specify what tests you want to write before actually writing any code. In this workflow, you might not even know what kind of test you want to write (e.g. HUnit, QuickCheck, etc.).
With tasty-autocollect
, you can use test_todo
to write down tests you’d like to write. By default, they’ll pass with a “TODO” message, but you can also pass --fail-todos
at runtime to make them fail instead.
test_todo = "a test to implement later"
Defining batches of tests
With tasty-autocollect
, you can write a set of tests in one definition without needing to nest them within a test group. For example,
test_batch =
[ testCase ("test #" ++ show x) $ pure ()
| x <- [1, 5, 10 :: Int]
]
is equivalent to writing:
test = testCase "test #1" $ pure ()
test = testCase "test #5" $ pure ()
test = testCase "test #10" $ pure ()
Integration with tasty-expected-failures
If you need to mark a test as an expected failure or just unconditionally skip a test, you can add an appropriate suffix to your test. For example:
test_expectFail = testCase "this test should fail" $ ...
test_expectFailBecause "Issue #123" = testCase "this test should fail" $ ...
test_ignoreTest = testCase "this test is skipped" $ ...
test_ignoreTestBecause "Issue #123" = testCase "this test is skipped" $ ...
The last example will be converted into the equivalent of:
tasty_test_4 :: TestTree
tasty_test_4 =
ignoreTestBecause "Issue #123" $
testCase "this test is skipped" $ ...
It also works in combination with other test types, e.g. with test_batch
to skip the entire batch of tests:
test_batch_expectFail =
[ testCase ("this test should fail: " ++ show x) ...
| x <- ...
]
test_prop_expectFailBecause :: Int -> Property
test_prop_expectFailBecause "Issue #123" "some property" x = x === x
Configuration
tasty-autocollect
can be configured by adding k = v
lines to the same block comment as AUTOCOLLECT.MAIN
; e.g.
{- AUTOCOLLECT.MAIN
suite_name = foo
# comments can start with a hash symbol
group_type = flat
-}
-
import
: A comma separated list of files (relative to the Main file) containing configuration to import- Recommended file extension:
.conf
- Configuration in files later in the list override configuration in files earlier in the list
- Configuration in the Main file override imported configuration
- Recommended file extension:
-
suite_name
: The name to use in thetestGroup
at the root of the test suiteTestTree
(defaults to the path of the main file) -
group_type
: How the tests should be grouped (defaults tomodules
)-
flat
: All the tests are in the same namespaceMain.hs test 1: OK test 2: OK test 3: OK
-
modules
: Tests are grouped by their moduleMain.hs Test.Module1 test1: OK test2: OK Test.Module2 test3: OK
-
tree
: Tests are grouped by their module, which is broken out into a treeMain.hs Test Module1 test1: OK test2: OK Module2 test3: OK
-
-
strip_suffix
: The suffix to strip from a test module, e.g.strip_suffix = Test
will relabel aFoo.BarTest
module toFoo.Bar
-
ingredients
: A comma-separated list of extra tasty ingredients to include, e.g.ingredients = SomeLibrary.ingredient1, SomeLibrary.ingredient2
-
ingredients_override
: By default,ingredients
will add the ingredients in front of the defaulttasty
ingredients. Whentrue
, does not automatically include the defaulttasty
ingredients, for complete control over the ingredient order. -
custom_main
: If you’d like fine-grained control over how theMain
module is generated (e.g. if you’re usingNoImplicitPrelude
or custom preludes), set this totrue
. When set, it will do the following replacements:{- AUTOCOLLECT.MAIN.imports -}
: replaced with the import lines needed for the tests.{- AUTOCOLLECT.MAIN.tests -}
: replaced with the[TestTree]
list, all on one line. If you’re using a formatter or linter, it might be helpful to dotests = id {- AUTOCOLLECT.MAIN.tests -}
so that the code still parses.
Due to current limitations, the above comments need to be matched exactly (e.g. not with
--
comments or extra whitespace).
Comparison with other libraries
tasty-discover
Advantages:
- Supports test functions with multiple arguments (e.g.
tasty-golden
) - Avoids hardcoding testers like
unit_
orprop_
- Avoids rewriting test label twice in function name
- Avoids test name restrictions
- Because
tasty-discover
couples the function name with the test label, you can’t do things like use punctuation in the test label. Sotasty-discover
doesn’t allow writing the equivalent oftestProperty "reverse . reverse === id"
.
- Because
- More features out-of-the-box (see “Features” section)
- More configurable
- More configuration options
- Configuration is more extensible, since configuration is parsed from a comment in the main module instead of as preprocessor arguments
Disadvantages:
- Uses both a preprocessor and a GHC plugin
tasty-discover
only uses a preprocessor- Haven’t tested performance yet, but I wouldn’t be surprised if there’s a non-negligible performance cost
tasty-th
Advantages:
- See
tasty-discover
- Automatically generates the
Main.hs
file that discovers + imports all test modules in the directorytasty-th
providesdefaultMainGenerator
, but it only discovers tests in the same module, so if you have tests in multiple files, you’d still have to manually import all of them into aMain.hs
file
Disadvantages:
- Uses a preprocessor and a GHC plugin
tasty-th
uses Template Haskell instead of either- Haven’t tested performance yet, but I wouldn’t be surprised if there’s a non-negligible performance cost
tasty-th
allows including a subset of functions, but not otherstasty-autocollect
includes all tests in one exported list
Appendix
Debugging
To inspect the generated Main module, build with -keep-tmp-files
, and look in $TMPDIR
for a ghc_1.hspp
file. (Upstream tickets: GHC, Stack)
To inspect the converted test modules, build with -ddump-rn -ddump-to-file
and look for the .dump-rn
files in .stack-work/
or dist-newstyle/
.
Note for Ormolu/Fourmolu
If you’re using Ormolu < 0.7 or Fourmolu < 0.13, use -- $AUTOCOLLECT.TEST.export$
instead; otherwise, the comment will be moved out of the export list.
This works around the issue by reusing Haddock’s named section syntax, but it shouldn’t be an issue because you shouldn’t be building Haddocks for test modules. If this becomes an issue, upgrade Ormolu or Fourmolu.
How it works
The package.yaml
/.cabal
snippet registers tasty-autocollect
as a preprocessor, which does one of three things at the very beginning of compilation:
- If the file contains
{- AUTOCOLLECT.MAIN -}
, find all test modules and generate a main module. - If the file contains
{- AUTOCOLLECT.TEST -}
, register thetasty-autocollect
GHC plugin to rewrite tests (see below). - Otherwise, do nothing
In a test file, the plugin will search for any functions named test
. It will then rename the function to tasty_test_N
, where N
is an autoincrementing, unique number. Then it will collect all the tests into a tasty_tests :: [TestTree]
binding, which is exported at the location of the {- AUTOCOLLECT.TEST.export -}
comment.
Changes
v0.4.1
- Add support for GHC 9.6
v0.4.0
- Drop support for GHC 8.10
- Added support for where clauses in
test_prop
, where the where clause may reference the generated arguments intest_prop
- Don’t autocollect invalid module names
- Enable importing configuration from other files
v0.3.2.0
- Added support for GHC 9.4
v0.3.1.0
- Fix bug where errors in Main module would show the path of the temporary file instead of the original file
- Ignore binary files in test directory
v0.3.0.0
- Fix bug when omitting signature after specifying a signature for a prior test
- Add support for
_expectFail
,_expectFailBecause
,_ignoreTest
,_ignoreTestBecause
suffixes
v0.2.0.0
- Fix build for GHC 8.10.2
- Greatly simplify framework by replacing
test_testCase
with justtest = testCase ...
v0.1.0.0
Initial release