perfect-numbers: use predicates instead exercism#232

Author: cmcaine

exercises/perfect-numbers/example.jl

@@ -9,16 +9,9 @@ function aliquot_sum(n)
     return sum(i for i in 1:div(n, 2) if n % i == 0)
 end
 
-function classify(n)
-    if !isinteger(n) || n < 1
-        throw(DomainError(n, "n must be a positive integer"))
-    end
-    s = aliquot_sum(n)
-    if s > n
-        :abundant
-    elseif s < n
-        :deficient
-    else
-        :perfect
-    end
-end
+isnatural(n) = isinteger(n) && n > zero(n)
+assert_natural(n) = isnatural(n) || throw(DomainError(n, "n must be a positive integer"))
+
+isabundant(n) = assert_natural(n) && aliquot_sum(n) > n
+isperfect(n) = assert_natural(n) && aliquot_sum(n) == n
+isdeficient(n) = assert_natural(n) && aliquot_sum(n) < n

exercises/perfect-numbers/runtests.jl

@@ -6,63 +6,67 @@ include("perfect-numbers.jl")
 @testset "Perfect numbers" begin
 
     @testset "Smallest perfect number is classified correctly" begin
-        @test classify(6) == :perfect
+        @test isperfect(6)
     end
 
     @testset "Medium perfect number is classified correctly" begin
-        @test classify(28) == :perfect
+        @test isperfect(28)
     end
 
     @testset "Large perfect number is classified correctly" begin
-        @test classify(33550336) == :perfect
+        @test isperfect(33550336)
     end
 end
 
 @testset "Abundant numbers" begin
 
     @testset "Smallest abundant number is classified correctly" begin
-        @test classify(12) == :abundant
+        @test isabundant(12)
     end
 
     @testset "Medium abundant number is classified correctly" begin
-        @test classify(30) == :abundant
+        @test isabundant(30)
     end
 
     @testset "Large abundant number is classified correctly" begin
-        @test classify(33550335) == :abundant
+        @test isabundant(33550335)
     end
 end
 
 @testset "Deficient numbers" begin
 
     @testset "Smallest prime deficient number is classified correctly" begin
-        @test classify(2) == :deficient
+        @test isdeficient(2)
     end
 
     @testset "Smallest non-prime deficient number is classified correctly" begin
-        @test classify(4) == :deficient
+        @test isdeficient(4)
     end
 
     @testset "Medium deficient number is classified correctly" begin
-        @test classify(32) == :deficient
+        @test isdeficient(32)
     end
 
     @testset "Large deficient number is classified correctly" begin
-        @test classify(33550337) == :deficient
+        @test isdeficient(33550337)
     end
 
     @testset "Edge case (no factors other than itself) is classified correctly" begin
-        @test classify(1) == :deficient
+        @test isdeficient(1)
     end
 end
 
 @testset "Invalid inputs" begin
 
     @testset "Zero is rejected (not a natural number)" begin
-        @test_throws DomainError classify(0)
+        @test_throws DomainError isdeficient(0)
+        @test_throws DomainError isperfect(0)
+        @test_throws DomainError isabundant(0)
     end
 
     @testset "Negative integer is rejected (not a natural number)" begin
-        @test_throws DomainError classify(-1)
+        @test_throws DomainError isdeficient(-1)
+        @test_throws DomainError isperfect(-1)
+        @test_throws DomainError isabundant(-1)
     end
 end

generators/perfect-numbers.jl

@@ -32,14 +32,16 @@ for i in f["cases"]
             global CODE *= """
 
                 @testset \"$des\" begin
-                    @test $property($inp) == :$exped
+                    @test is$exped($inp)
                 end
             """
         else
             global CODE *= """
 
                 @testset \"$des\" begin
-                    @test_throws DomainError classify($inp)
+                    @test_throws DomainError isdeficient($inp)
+                    @test_throws DomainError isperfect($inp)
+                    @test_throws DomainError isabundant($inp)
                 end
             """
         end