Add extra tests for stable sorting algorithms

Author: LSchwerdt

test/runtests.jl

@@ -3,9 +3,12 @@ using Test
 using StatsBase
 using Random
 
+stable_algorithms = [TimSort, RadixSort, PagedMergeSort, ThreadedPagedMergeSort]
+unstable_algorithms = [HeapSort, CombSort]
+
 a = rand(1:10000, 1000)
 
-for alg in [TimSort, HeapSort, RadixSort, CombSort, PagedMergeSort, ThreadedPagedMergeSort]
+for alg in [stable_algorithms; unstable_algorithms]
     b = sort(a, alg=alg)
     @test issorted(b)
     ix = sortperm(a, alg=alg)
@@ -73,8 +76,7 @@ for n in [0:10..., 100, 101, 1000, 1001]
         invpermute!(c, pi)
         @test c == v
 
-        # stable algorithms
-        for alg in [TimSort, RadixSort, PagedMergeSort, ThreadedPagedMergeSort]
+        for alg in stable_algorithms
             p = sortperm(v, alg=alg, order=ord)
             @test p == pi
             s = copy(v)
@@ -84,8 +86,7 @@ for n in [0:10..., 100, 101, 1000, 1001]
             @test s == v
         end
 
-        # unstable algorithms
-        for alg in [HeapSort, CombSort]
+        for alg in unstable_algorithms
             p = sortperm(v, alg=alg, order=ord)
             @test isperm(p)
             @test v[p] == si
@@ -99,7 +100,7 @@ for n in [0:10..., 100, 101, 1000, 1001]
 
     v = randn_with_nans(n,0.1)
     for ord in [Base.Order.Forward, Base.Order.Reverse],
-        alg in [TimSort, HeapSort, RadixSort, CombSort, PagedMergeSort, ThreadedPagedMergeSort]
+        alg in [stable_algorithms; unstable_algorithms]
         # test float sorting with NaNs
         s = sort(v, alg=alg, order=ord)
         @test issorted(s, order=ord)
@@ -117,3 +118,14 @@ for n in [0:10..., 100, 101, 1000, 1001]
         @test reinterpret(UInt64,vp) == reinterpret(UInt64,s)
     end
 end
+
+for T in (Float64, Int, UInt8)
+    for alg in stable_algorithms
+        for ord in [Base.Order.By(identity), Base.Order.By(_ -> 0), Base.Order.By(Base.Fix2(÷, 100))]
+            for n in vcat(0:31, 40:11:100, 110:51:1000)
+                v = sort(rand(T, n))
+                @test v == sort(v; alg=alg, order=ord)
+            end
+        end
+    end
+end