{- | This module provides a short tutorial on how to use the HTF. It assumes that you are using GHC for compiling your Haskell code. (It is possible to use the HTF with other Haskell environments, only the steps taken to invoke the custom preprocessor of the HTF may differ in this case.) We start with a simple example. Then we show how to use HTF to easily collect test definitions from multiple modules and discuss backwards-compatibility for projects already using `HUnit`. Finally, we give a brief cookbook-like summary on how to setup your tests with HTF. -} module Test.Framework.Tutorial ( -- * A simple example {- | Suppose you are trying to write a function for reversing lists : @ myReverse :: [a] -> [a] myReverse [] = [] myReverse [x] = [x] myReverse (x:xs) = myReverse xs @ To test this function using the HTF, you would first create a new source file with a @OPTIONS_GHC@ pragma in the first line. @ {-# OPTIONS_GHC -F -pgmF htfpp #-} @ This pragma instructs GHC to run the source file through @htfpp@, the custom preprocessor of the HTF. The following @import@ statements are also needed: @ import System.Environment ( getArgs ) import System.Exit ( exitWith ) import Test.Framework @ The actual unit tests and QuickCheck properties are defined like this: @ test_nonEmpty = do assertEqual [1] (myReverse [1]) assertEqual [3,2,1] (myReverse [1,2,3]) test_empty = assertEqual ([] :: [Int]) (myReverse []) prop_reverse :: [Int] -> Bool prop_reverse xs = xs == (myReverse (myReverse xs)) @ When @htfpp@ consumes the source file, it replaces the @assertEqual@ tokens (and other @assert@-like tokens, see "Test.Framework.HUnitWrapper") with calls to 'assertEqual_', passing the current location in the file as the first argument. Moreover, the preprocessor collects all top-level definitions starting with @test_@ or @prop_@ in a test suite of type 'TestSuite' and name @htf_@/M/@_thisModulesTests@, where /M/ is the name of the current module with dots @.@ replaced by underscores @_@. For your convenience, the preprocessor also defines the token @htf_thisModulesTests@ as a shorthand for the rather lengthy name @htf_@/M/@_thisModulesTests@. Definitions starting with @test_@ denote unit tests and must be of type 'Assertion'. Definitions starting with @prop_@ denote QuickCheck properties and must be of type /T/ such that /T/ is an instance of the type class 'Testable'. To run the tests, use the 'htfMain' function. @ main = htfMain htf_thisModulesTests @ Here is the skeleton of a @.cabal@ file which you may want to use to compile the tests. @ Name: HTF-tutorial Version: 0.1 Cabal-Version: >= 1.10 Build-type: Simple Executable tutorial Type: exitcode-stdio-1.0 Main-is: Tutorial.hs Build-depends: base == 4.*, HTF == 0.10.* Default-language: Haskell2010 @ Compiling the program just shown (you must include the code for @myReverse@ as well), and then running the resulting program with no further commandline arguments yields the following output (colors had to be omitted, so the diff output does not look very useful): > [TEST] Main:nonEmpty (Tutorial.hs:17) > assertEqual failed at Tutorial.hs:18 > * expected: [3, 2, 1] > * but got: [3] > * diff: [3, 2, 1] > *** Failed! (0ms) > > [TEST] Main:empty (Tutorial.hs:19) > +++ OK (0ms) > > [TEST] Main:reverse (Tutorial.hs:22) > Falsifiable (after 6 tests and 5 shrinks): > [0,0] > Replay argument: "Just (200055706 2147483393,5)" > *** Failed! (0ms) > > [TEST] Main:reverseReplay (Tutorial.hs:24) > Falsifiable (after 1 test and 2 shrinks): > [0,0] > Replay argument: "Just (1060394807 2147483396,2)" > *** Failed! (0ms) > > * Tests: 4 > * Passed: 1 > * Pending: 0 > * Failures: 3 > * Errors: 0 > > * Failures: > * Main:reverseReplay (Tutorial.hs:24) > * Main:reverse (Tutorial.hs:22) > * Main:nonEmpty (Tutorial.hs:17) > > Total execution time: 4ms (To check only specific tests, you can pass commandline arguments to the program: the HTF then runs only those tests whose name contain at least one of the commandline arguments as a substring.) You see that the message for the first failure contains exact location information, which is quite convenient. Also, HTF provides a diff between the expected and the given output. (For this simple example, a diff is kind of useless, but with longer output strings, a diff allows you to identify very quickly where the expected and the given results disagree.) For the QuickCheck property @Main.reverse@, the HTF outputs a string represenation of the random generator used to check the property. This string representation can be used to replay the property. (The replay feature may not be useful for this simple example but it helps in more complex scenarios). To replay a property you simply use the string representation of the generator to define a new QuickCheck property with custom arguments: @ prop_reverseReplay = 'withQCArgs' (\\a -> a { 'replay' = 'read' \"Just (1060394807 2147483396,2)\" }) prop_reverse @ To finish this simple example, we now give a correct definition for @myReverse@: @ myReverse :: [a] -> [a] myReverse [] = [] myReverse (x:xs) = myReverse xs ++ [x] @ Running our tests again on the fixed definition then yields the desired result: > [TEST] Main:nonEmpty (Tutorial.hs:17) > +++ OK (0ms) > > [TEST] Main:empty (Tutorial.hs:19) > +++ OK (0ms) > > [TEST] Main:reverse (Tutorial.hs:22) > Passed 100 tests. > +++ OK (20ms) > > [TEST] Main:reverseReplay (Tutorial.hs:24) > Passed 100 tests. > +++ OK (4ms) > > * Tests: 4 > * Passed: 4 > * Pending: 0 > * Failures: 0 > * Errors: 0 > > Total execution time: 28ms The HTF also allows the definition of black box tests. Essentially, black box tests allow you to verify that the output of your program matches your expectations. See the documentation of the "Test.Framework.BlackBoxTest" module for further information. -} -- * Test definitions in multiple modules {- | For testing real-world programs or libraries, it is often conventient to split the tests into several modules. For example, suppose your library contains of two modules @MyPkg.A@ and @MyPkg.B@, each containing test functions. You can find a slightly extended of this scenario in the samples directory of the HTF source tree, see .) File @MyPkg/A.hs@ @ {-# OPTIONS_GHC -F -pgmF htfpp #-} module MyPkg.A (funA, htf_thisModulesTests) where import Test.Framework funA :: Int -> Int funA x = x + 1 test_funA1 = assertEqual (funA 41) 42 test_funA2 = assertEqual (funA 2) 3 @ File @MyPkg/B.hs@ @ {-# OPTIONS_GHC -F -pgmF htfpp #-} module MyPkg.B (funB, htf_thisModulesTests) where import Test.Framework funB :: Int -> Int funB x = x * 2 test_funB1 = assertEqual (funB 21) 42 test_funB2 = assertEqual (funB 0) 0 @ For module @MyPkg.A@, the @htfpp@ preprocessor collects the modules' testcases into a variable @htf_MyPkg_A_thisModulesTests@ and defines a preprocessor token @thisModulesTests@ as a shorthand for this variable. Thus, to expose all HTF tests defined in @MyPkg.A@, we only need to put @thisModulesTests@ into the export list. The same holds analogously for module @MyPkg.B@. To execute all tests defined in these two modules, you would create a main module and import @MyPkg.A@ and @MyPkg.B@ with the special import annotation @{-@ HTF_TESTS @-}@. The effect of this annotation is that the @htfpp@ preprocessor makes all test cases defined in such modules imported available in a variable called @htf_importedTests@. Thus, your main module would look like this: File @TestMain.hs@ @ {-# OPTIONS_GHC -F -pgmF htfpp #-} module Main where import Test.Framework import Test.Framework.BlackBoxTest import {-@ HTF_TESTS @-} MyPkg.A import {-@ HTF_TESTS @-} MyPkg.B main = htfMain htf_importedTests @ -} -- * Machine-readable output {- | For better integration with your testing environment, HTF provides the ability to produce machine-readable output in JSON format. Here is a short example how the JSON output looks like, for details see "Test.Framework.JsonOutput": > {"test":{"flatName":"Main:nonEmpty","location":{"file":"Tutorial.hs","line":17},"path":["Main","nonEmpty"],"sort":"unit-test"},"type":"test-start"} > ;; > {"result":"pass","message":"","test":{"flatName":"Main:nonEmpty","location":{"file":"Tutorial.hs","line":17},"path":["Main","nonEmpty"],"sort":"unit-test"},"wallTime":0,"type":"test-end","location":null} > ;; > {"test":{"flatName":"Main:empty","location":{"file":"Tutorial.hs","line":19},"path":["Main","empty"],"sort":"unit-test"},"type":"test-start"} > ;; > {"result":"pass","message":"","test":{"flatName":"Main:empty","location":{"file":"Tutorial.hs","line":19},"path":["Main","empty"],"sort":"unit-test"},"wallTime":0,"type":"test-end","location":null} > ;; > {"test":{"flatName":"Main:reverse","location":{"file":"Tutorial.hs","line":22},"path":["Main","reverse"],"sort":"quickcheck-property"},"type":"test-start"} > ;; > {"result":"pass","message":"Passed 100 tests.","test":{"flatName":"Main:reverse","location":{"file":"Tutorial.hs","line":22},"path":["Main","reverse"],"sort":"quickcheck-property"},"wallTime":19,"type":"test-end","location":null} > ;; > {"test":{"flatName":"Main:reverseReplay","location":{"file":"Tutorial.hs","line":24},"path":["Main","reverseReplay"],"sort":"quickcheck-property"},"type":"test-start"} > ;; > {"result":"pass","message":"Passed 100 tests.","test":{"flatName":"Main:reverseReplay","location":{"file":"Tutorial.hs","line":24},"path":["Main","reverseReplay"],"sort":"quickcheck-property"},"wallTime":4,"type":"test-end","location":null} > ;; > {"failures":0,"passed":4,"pending":0,"wallTime":39,"errors":0,"type":"test-results"} > ;; Machine-readable ouput is requested by the @--json@ flag. You can specify a dedicated output file using the @--output-file=@ option. On some platforms (e.g. Windows) it might not be possible to read from the output file while the tests are running (due to file-locking). In this case, you might want to use the @--split@ option. With this option, HTF writes each JSON message to a separate ouput file. The name of the output file is derived from the name given with the @--output-file=@ flag by appending an index (starting at 0) that is incremented for every message. -} -- * Backwards-compatibility with HUnit {- | The types of the various @assert@-like macros of the HTF are not backwards-compatible with the corresponding functions of HUnit. This incompatibility is intentional, of course: with HUnit, the programmer has to provide suitable location information by explicitly passing a string argument to the @assert@-like functions, whereas HTF provides location information implicitly through its pre-processor @htfpp@. To simplify transition from HUnit to HTF, @htfpp@ provides a commandline flag @--hunit@. This flag causes @htfpp@ to exand the assertion macros in a way compatible with the types of the corresponding HUnit functions. For example, with the @--hunit@ flag being present, @assertEqual@ is exanded to @'assertEqualVerbose_' ('makeLoc' \"filename\" line)@, whose type @(Show a, Eq a) => String -> a -> a -> IO ()@ is compatible with the type of HUnit's 'Test.HUnit.Base.assertEqual' function. -} -- * Summary {- | Here is a quick summary of how to write, collect, and execute your tests. You should also have a look at the sample project at . -} -- ** Writing tests {- | * Place @{-# OPTIONS_GHC -F -pgmF htfpp #-}@ at the top of your module. * Put @htf_thisModulesTests@ into the export list of your module. * Import @Test.Framework@. * Prefix your unit tests with @test_@, see "Test.Framework.HUnitWrapper" for the assertions provided. * Prefix your QuickCheck properties with @prop_@. -} -- ** Collecting and executing tests {- | * Place @{-# OPTIONS_GHC -F -pgmF htfpp #-}@ at the top of your module. * Import @Test.Framework@. * Import modules defining HTF tests with @import {-@ HTF_TESTS @-} MyPkg.A@. * Use @main = htfMain htf_importedTests@ to run all imported tests. -} ) where import Test.Framework import qualified Test.HUnit.Base