Relax some tests that are satisfied only up to some floating point error. (#59)

Author: leftaroundabout

arrayfire.cabal

@@ -144,6 +144,8 @@ test-suite test
     exitcode-stdio-1.0
   main-is:
     Main.hs
+  other-modules:
+    Test.Hspec.ApproxExpect
   hs-source-dirs:
     test
   build-depends:
@@ -154,7 +156,8 @@ test-suite test
     HUnit,
     QuickCheck,
     quickcheck-classes,
-    vector
+    vector,
+    call-stack >=0.4 && <0.5
   if !flag(disable-build-tool-depends)
     build-tool-depends:
       hspec-discover:hspec-discover

test/ArrayFire/LAPACKSpec.hs

@@ -4,6 +4,7 @@ module ArrayFire.LAPACKSpec where
 import qualified ArrayFire       as A
 import           Prelude
 import           Test.Hspec
+import Test.Hspec.ApproxExpect
 
 spec :: Spec
 spec =
@@ -33,9 +34,9 @@ spec =
     it "Should get determinant of Double" $ do
       let eles = [[3 A.:+ 1, 8 A.:+ 1], [4 A.:+ 1, 6 A.:+ 1]]
           (x,y) = A.det (A.matrix @(A.Complex Double) (2,2) eles)
-      x `shouldBe` (-14)
+      x `shouldBeApprox` (-14)
       let (x,y) = A.det $ A.matrix @Double (2,2) [[3,8],[4,6]]
-      x `shouldBe` (-14)
+      x `shouldBeApprox` (-14)
 --    it "Should calculate inverse" $ do
 --      let x = flip A.inverse A.None $ A.matrix @Double (2,2) [[4.0,7.0],[2.0,6.0]]
 --      x `shouldBe` A.matrix (2,2) [[0.6,-0.7],[-0.2,0.4]]

test/ArrayFire/StatisticsSpec.hs

@@ -5,6 +5,7 @@ import ArrayFire    hiding (not)
 
 import Data.Complex
 import Test.Hspec
+import Test.Hspec.ApproxExpect
 
 spec :: Spec
 spec =
@@ -15,7 +16,7 @@ spec =
            5.5
     it "Should find the weighted-mean" $ do
       meanWeighted (vector @Double 10 [1..]) (vector @Double 10 [1..]) 0
-        `shouldBe`
+        `shouldBeApprox`
            7.0
     it "Should find the variance" $ do
       var (vector @Double 8 [1..8]) False 0

test/Test/Hspec/ApproxExpect.hs

@@ -0,0 +1,19 @@
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+module Test.Hspec.ApproxExpect where
+
+import Data.CallStack (HasCallStack)
+
+import Test.Hspec (shouldSatisfy, Expectation)
+
+infix 1 `shouldBeApprox`
+
+shouldBeApprox :: (HasCallStack, Show a, Fractional a, Eq a)
+    => a -> a -> Expectation
+shouldBeApprox actual tgt
+       -- This is a hackish way of checking, without requiring a specific
+       -- type or an 'Ord' instance, whether two floating-point values
+       -- are only some epsilons apart: when the difference is small enough
+       -- so scaling it down some more makes it a no-op for addition.
+   = actual `shouldSatisfy` \x -> (x-tgt) * 1e-4 + tgt == tgt
+