Add a test for too large inputs

Author: sharkdp

src/Data/Number.purs

@@ -1,11 +1,11 @@
 -- | A module for working with PureScripts builtin `Number` type.
 module Data.Number
   ( Fraction
+  , fromString
   , eqRelative
   , eqApproximate
   , (~=)
   , (≅)
-  , fromString
   , neqApproximate
   , (≇)
   , Precision
@@ -19,7 +19,9 @@ import Math (abs)
 import Global (readFloat, isFinite)
 
 
--- | Attempt to parse a Number from a String using JavaScript's parseFloat.
+-- | Attempt to parse a `Number` from a `String` using JavaScripts
+-- | `parseFloat`. Returns `Nothing` if the parse fails or if the result is not
+-- | a finite number.
 -- |
 -- | Example:
 -- | ```purs
@@ -34,6 +36,9 @@ import Global (readFloat, isFinite)
 -- |
 -- | > fromString "1.2e4"
 -- | (Just 12000.0)
+-- |
+-- | > fromString "bad"
+-- | Nothing
 -- | ```
 fromString ∷ String → Maybe Number
 fromString = readFloat >>> check

test/Main.purs

@@ -2,7 +2,7 @@ module Test.Main where
 
 import Prelude
 
-import Data.Maybe (fromMaybe)
+import Data.Maybe (Maybe(..), fromMaybe)
 import Data.Number (eqRelative, eqAbsolute, fromString, (≅), (≇))
 
 import Control.Monad.Aff.AVar (AVAR)
@@ -136,7 +136,11 @@ main = runTest do
 
     test "invalid number string" do
       assert "invalid strings are not coerced" $
-        fromMaybe true $ false <$ fromString "bad string"
+        Nothing == fromString "bad string"
+
+    test "too large numbers" do
+      assert "too large numbers are not coerced" $
+        Nothing == fromString "1e1000"
 
 
   suite "eqAbsolute" do