diff --git a/unittest.cpp b/unittest.cpp
new file mode 100644
index 0000000..662c82c
--- /dev/null
+++ b/unittest.cpp
@@ -0,0 +1,41 @@
+#define DOCTEST_CONFIG_NO_MULTITHREADING
+#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
+#include "doctest.h"
+#include "histogram_internal.h"
+
+TEST_CASE("distinct positive numbers") {
+    double min = 0;
+    double max = 0;
+    find_minmax({1, 2}, min, max);
+    CHECK(min == 1);
+    CHECK(max == 2);
+}
+
+TEST_CASE("empty vector") {
+    double min = 0;
+    double max = 0;
+    find_minmax({NULL}, min, max);
+    CHECK(min == 0);
+    CHECK(max == 0);
+}
+TEST_CASE("one element") {
+    double min = 0;
+    double max = 0;
+    find_minmax({5}, min, max);
+    CHECK (min == 5);
+    CHECK (max == 5);
+}
+TEST_CASE("negative elements") {
+    double min = 0;
+    double max = 0;
+    find_minmax({-2, -3}, min, max);
+    CHECK (min == -3);
+    CHECK (max == -2);
+}
+TEST_CASE("identical elements") {
+    double min = 0;
+    double max = 0;
+    find_minmax({3, 3, 3}, min, max);
+    CHECK (min == 3);
+    CHECK (max == 3);
+}