✅ haskell: space-age

haskell/space-age/test/Tests.hs

@@ -0,0 +1,79 @@
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Data.Function     (on)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import SpaceAge (Planet(..), ageOn)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = describe "ageOn" $ for_ cases test
+  where
+    -- Here we used `fromIntegral`, `fromRational` and `toRational` to
+    -- generalize the test suite, allowing any function that takes a
+    -- `Planet` and a number, returning an instance of `Real`.
+    test Case{..} = it description $ expression `shouldBeAround` expected
+      where
+        expression = fromRational
+                   . toRational
+                   . ageOn planet
+                   . fromIntegral
+                   $ seconds
+        shouldBeAround = shouldBe `on` roundTo 2
+        roundTo n = (/ 10 ^ n) . fromIntegral . round . (* 10 ^ n)
+
+data Case = Case { description :: String
+                 , planet      :: Planet
+                 , seconds     :: Integer
+                 , expected    :: Double
+                 }
+
+cases :: [Case]
+cases = [ Case { description = "Earth"
+               , planet      = Earth
+               , seconds     = 1000000000
+               , expected    = 31.69
+               }
+        , Case { description = "Mercury"
+               , planet      = Mercury
+               , seconds     = 2134835688
+               , expected    = 280.88
+               }
+        , Case { description = "Venus"
+               , planet      = Venus
+               , seconds     = 189839836
+               , expected    = 9.78
+               }
+        , Case { description = "Mars"
+               , planet      = Mars
+               , seconds     = 2129871239
+               , expected    = 35.88
+               }
+        , Case { description = "Jupiter"
+               , planet      = Jupiter
+               , seconds     = 901876382
+               , expected    = 2.41
+               }
+        , Case { description = "Saturn"
+               , planet      = Saturn
+               , seconds     = 2000000000
+               , expected    = 2.15
+               }
+        , Case { description = "Uranus"
+               , planet      = Uranus
+               , seconds     = 1210123456
+               , expected    = 0.46
+               }
+        , Case { description = "Neptune"
+               , planet      = Neptune
+               , seconds     = 1821023456
+               , expected    = 0.35
+               }
+        ]
+
+-- 33c40fce28c835600282d0bfdc589d7c6d785f6e