implemented newAbacus

abacus.cabal

@@ -50,6 +50,7 @@ test-suite abacus-test
   type: exitcode-stdio-1.0
   main-is: Spec.hs
   other-modules:
+      AbacusSpec
       Paths_abacus
   autogen-modules:
       Paths_abacus

src/Abacus.hs

@@ -28,13 +28,16 @@ module Abacus (Abacus, newAbacus) where
 
 import Abacus.Internal
 
--- | Constructs the initial state of a new "Abacus"
+-- | Constructs the initial state of a new "Abacus"; will return
+-- "Nothing" if the input paramebers are invalid.
 newAbacus
   :: Int
-  -- ^ The number of beads on each rung
+  -- ^ The number of beads on each rung (must be at least one)
   -> Int
-  -- ^ The number of rungs
+  -- ^ The number of rungs (must be at least one)
   -> Maybe Abacus
-newAbacus = undefined
+newAbacus beads rungs = if beads < 1 || rungs < 1
+  then Nothing
+  else Just $ Abacus beads $ replicate rungs 0
 
 --jl

test/AbacusSpec.hs

@@ -0,0 +1,45 @@
+{-
+
+abacus
+Copyright (C) Jonathan Lamothe <jonathan@jlamothe.net>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public
+License along with this program.  If not, see
+<https://www.gnu.org/licenses/>.
+
+-}
+
+module AbacusSpec (spec) where
+
+import Test.Hspec (Spec, context, describe, it, shouldBe)
+
+import Abacus
+import Abacus.Internal
+
+spec :: Spec
+spec = describe "Abacus"
+  newAbacusSpec
+
+newAbacusSpec :: Spec
+newAbacusSpec = describe "newAbacusSpec" $ mapM_
+  ( \(desc, beads, rungs, expected) -> context desc $ let
+    actual = newAbacus beads rungs
+    in it ("should be " ++ show expected) $
+      actual `shouldBe` expected
+  )
+  [ ( "valid",    10, 3, Just $ Abacus 10 [0, 0, 0] )
+  , ( "no beads", 0,  3, Nothing                    )
+  , ( "no rungs", 10, 0, Nothing                    )
+  ]
+
+--jl

test/Spec.hs

@@ -21,7 +21,10 @@ License along with this program.  If not, see
 
 import Test.Hspec (hspec)
 
+import qualified AbacusSpec as Abacus
+
 main :: IO ()
-main = hspec $ return ()
+main = hspec
+  Abacus.spec
 
 -- jl