Hello! Thanks for your answer!
You probably want something like...
l = [0, 255, 255, 255, 255, 0, 255, 255, 255, 255, 0, 255, 255, 255, 255, 0] testConvertToList01 = do img <- readImage "../data-test/diagonalImage.pgm" return $ TestCase $ assertEqual "" l (convertToList img)
When I use this test case definition, I'm getting an error when constructing the test suite: tests = TestList [testCommentLine01, testCommentLine02, testConvertToList01] GHCi writes TestLik.hs:22: Couldn't match `Test' against `IO Test' Expected type: Test Inferred type: IO Test In the list element: testConvertToList01 In the first argument of `TestList', namely `[testCommentLine01, testCommentLine02, testConvertToList01]' Best regards Dmitri Pissarenko -- Dmitri Pissarenko Software Engineer http://dapissarenko.com