为Haskell生成错误的Cabal测试

Question

我的Main.hs文件接受命令行参数：

module Main (toLowerStr, Result(..), grade, main) where
...
grade :: [String] -> String -> String -> (Bool, Result, [Highlight])
    grade dictWords correctAnswer studentAnswer =
            ...
...
main :: IO ()
main = do
        args <- getArgs
        dict <- readFile $ args !! 0
        ...

这很好，除非我试着测试。我的测试文件是

module Testing where
import Main
import Test.Hspec
main :: IO ()
main = do
        dict <- readFile "dict.txt"
        let dictWords = map toLowerStr $ lines dict
        hspec $ do
        describe "Validate passing answers" $ do
                it "Match should be verified exactly" $ do
                        grade dictWords "house" "house"
                              `shouldBe` (True, Perfect, [])

然而，当我运行cabal test时，它仍然会给我

Preprocessing test suite 'tests' for grade-0.1.0.0...
[2 of 2] Compiling Testing          ( src/HSpecTests.hs, dist/build/tests/tests-tmp/Testing.o )
Linking dist/build/tests/tests ...
Running 1 test suites...
Test suite tests: RUNNING...
tests: Prelude.(!!): index too large
Test suite tests: FAIL

我确信它之所以失败，是因为在Main.main中调用了args，因为可执行文件本身运行良好，而且我看不到!!在其他任何地方被使用。

如何运行测试？

EDIT：在Main.hs:中使用模式匹配

main :: IO ()
main = do
        [filename, correctString, studentString] <- getArgs
        ...

现在错误是

[1 of 2] Compiling Main             ( src/Main.hs, dist/build/tests/tests-tmp/Main.o )
Linking dist/build/tests/tests ...
Running 1 test suites...
Test suite tests: RUNNING...
tests: user error (Pattern match failure in do expression at src/Main.hs:141:9-48)
Test suite tests: FAIL

编辑2：我的整个grade.cabal文件

-- Initial grade.cabal generated by cabal init.  For further documentation,
--  see http://haskell.org/cabal/users-guide/
name:                grade
version:             0.1.0.0
-- synopsis:            
-- description:         
license-file:        LICENSE
author:              Amos Ng <[e-mail]>
maintainer:          Amos Ng <[e-mail]>
-- copyright:           
category:            Language
build-type:          Simple
cabal-version:       >=1.8
executable grade
  main-is:             Main.hs
  -- other-modules:       
  build-depends:       base, split ==0.2.*
  hs-source-dirs:      src
test-suite tests
  ghc-options:         -Wall
  type: exitcode-stdio-1.0
  main-is:             HSpecTests.hs
  other-modules:       Main
  build-depends:       base, split ==0.2.*, hspec ==1.11.*
  hs-source-dirs:      src

Answer 1

GHC将始终使用名为Main的模块中名为main的函数作为入口点。由于HSpecTests.hs是Testing模块，而不是Main模块，因此它的main被完全忽略，而倾向于Main模块中的main。您应该将逻辑从Main模块中分离出来，将Main模块作为命令行存根。然后，您需要将其从测试构建中排除，并在HSpecTests.hs中将模块Testing更改为模块Main。