add tests for _replace

Author: OkonSamuel

test/runtests.jl

@@ -1,5 +1,6 @@
-import MultivariateStats
 import Dates
+import MLJMultivariateStatsInterface: _replace!
+import MultivariateStats
 import Random
 
 using LinearAlgebra

test/utils.jl

@@ -1,3 +1,15 @@
+@testset "replace!" begin
+    y = [1, 2, 2, 2, 3]
+    z1 = 1:5
+    z2 = 0:3
+    r1 = -2:2
+    r2 = 2:5    
+    @test_throws DimensionMismatch _replace!(y, z1, r2)
+    @test_throws DimensionMismatch _replace!(y, z2, r1)
+    @test _replace!(deepcopy(y), z1, r1) == Base.replace!(deepcopy(y), (z1 .=> r1)...)
+    @test _replace!(deepcopy(y), z2, r2) == Base.replace!(deepcopy(y), (z2 .=> r2)...)
+end
+
 @testset "softmax" begin
     X = rand(100,5)
     max_ = maximum(X, dims=2)