added insertion sort and regression test

tests/sort_regression_test.cc

@@ -0,0 +1,39 @@
+/*
+Regression Test for sorting
+
+Copyright 2024 Ahmet Inan <inan@aicodix.de>
+*/
+
+#include <random>
+#include <cassert>
+#include <iostream>
+#include <algorithm>
+#include <functional>
+#include "sort.hh"
+
+int main()
+{
+	std::random_device rd;
+	typedef std::default_random_engine generator;
+	typedef std::uniform_int_distribution<int> distribution;
+	auto rand = std::bind(distribution(1, 32), generator(rd()));
+	int a[32], b[32], c[32], d[32], e[32], f[32];
+	for (int loop = 0; loop < 1000000; ++loop) {
+		int size = rand();
+		for (int i = 0; i < size; ++i)
+			a[i] = b[i] = c[i] = d[i] = rand();
+		std::sort(a, a+size);
+		insertion_sort(b, size);
+		for (int i = 0; i < size; ++i)
+			assert(a[i] == b[i]);
+		for (int i = 0; i < size; ++i)
+			e[i] = i;
+		std::stable_sort(e, e+size, [c](int i, int j){ return c[i] < c[j]; });
+		insertion_sort(f, d, size);
+		for (int i = 0; i < size; ++i)
+			assert(e[i] == f[i]);
+	}
+	std::cerr << "Sorting regression test passed!" << std::endl;
+	return 0;
+}
+