From 395c9697b6121d3d51aabaf4af2d5aeb09e67757 Mon Sep 17 00:00:00 2001
From: Rob Keim <robkeim@gmail.com>
Date: Tue, 10 Jan 2017 21:20:20 -0800
Subject: [PATCH] Update Luhn tests for #491

---
 exercises/luhn/Example.fs  | 32 +++++++++++++-------------
 exercises/luhn/LuhnTest.fs | 46 +++++++-------------------------------
 2 files changed, 23 insertions(+), 55 deletions(-)

diff --git a/exercises/luhn/Example.fs b/exercises/luhn/Example.fs
index 0e78cf039..d6a3c8d5e 100644
--- a/exercises/luhn/Example.fs
+++ b/exercises/luhn/Example.fs
@@ -1,29 +1,27 @@
 module Luhn
-        
-let digit c = (int)c - (int)'0'
-let digits number = number.ToString() |> Seq.map digit
 
-let addend index digit = 
+let private digit c = (int)c - (int)'0'
+let private digits number = number.ToString() |> Seq.map digit
+
+let private addend index digit = 
     if (index % 2 = 0) then digit else 
     if (digit >= 5) then digit * 2 - 9 
     else digit * 2
 
-let checkDigit (number:int64) = number % 10L
-
-let addends (number:int64) = 
-    number 
-    |> digits 
+let private addends number = 
+    number
     |> List.ofSeq 
     |> List.rev 
     |> List.mapi addend 
     |> List.rev
 
-let checksum (number:int64) = (number |> addends |> List.sum) % 10
-
-let valid (number:int64) = checksum number = 0
-
-let create (target:int64) = 
-    let targetNumber = target * 10L
+let private checksum number = (number |> digits |> addends |> List.sum) % 10
 
-    if valid targetNumber then targetNumber
-    else targetNumber + 10L - (int64)(checksum targetNumber)
\ No newline at end of file
+let valid (number : string) =
+    let noSpaces = number.Replace(" ", "")
+    match Seq.length noSpaces with
+    | 0 | 1 -> false
+    | _ ->
+        match Seq.forall (fun c -> c >= '0' && c <= '9') noSpaces with
+        | false -> false
+        | true  -> checksum noSpaces = 0
\ No newline at end of file
diff --git a/exercises/luhn/LuhnTest.fs b/exercises/luhn/LuhnTest.fs
index 8ac97f753..1f6d66609 100644
--- a/exercises/luhn/LuhnTest.fs
+++ b/exercises/luhn/LuhnTest.fs
@@ -3,41 +3,11 @@ module LuhnTest
 open NUnit.Framework
 open Luhn
   
-[<Test>]
-let ``Check digit is the rightmost digit`` () =
-    Assert.That(checkDigit 34567L, Is.EqualTo 7)
-
-[<Test>]
-[<Ignore("Remove to run test")>]
-let ``Addends doubles every other number from the right`` () =
-    Assert.That(addends 12121L, Is.EqualTo [1; 4; 1; 4; 1])
-
-[<Test>]
-[<Ignore("Remove to run test")>]
-let ``Addends subtracts 9 when doubled number is more than 9`` () =
-    Assert.That(addends 8631L, Is.EqualTo [7; 6; 6; 1])
-
-[<TestCase(4913, ExpectedResult = 2)>]
-[<TestCase(201773, ExpectedResult = 1)>]
-let ``Checksum adds addends together`` (number) =
-    checksum number
-
-[<TestCase(738, ExpectedResult = false)>]
-[<TestCase(8739567, ExpectedResult = true)>]
-let ``Number is valid when checksum mod 10 is zero`` (number) =
-    valid number
-
-[<Test>]
-[<Ignore("Remove to run test")>]
-let ``Luhn can create simple numbers with valid check digit`` () =
-    Assert.That(create 123L, Is.EqualTo(1230))
-
-[<Test>]
-[<Ignore("Remove to run test")>]
-let ``Luhn can create larger numbers with valid check digit`` () =
-    Assert.That(create 873956L, Is.EqualTo(8739567))
-
-[<Test>]
-[<Ignore("Remove to run test")>]
-let ``Luhn can create huge numbers with valid check digit`` () =
-    Assert.That(create 837263756L, Is.EqualTo(8372637564L))
\ No newline at end of file
+[<TestCase("1", ExpectedResult = false)>] // single digit strings can not be valid
+[<TestCase("0", ExpectedResult = false, Ignore = "Remove to run test")>] // a single zero is invalid
+[<TestCase("046 454 286", ExpectedResult = true, Ignore = "Remove to run test")>] // valid Canadian SIN
+[<TestCase("046 454 287", ExpectedResult = false, Ignore = "Remove to run test")>] // invalid Canadian SIN
+[<TestCase("8273 1232 7352 0569", ExpectedResult = false, Ignore = "Remove to run test")>] // invalid credit card
+[<TestCase("827a 1232 7352 0569", ExpectedResult = false, Ignore = "Remove to run test")>] // strings that contain non-digits are not valid
+let ``Validate checksum`` number =
+    valid number
\ No newline at end of file