diff --git a/unittest.cpp b/unittest.cpp
new file mode 100644
index 0000000..5a66cbd
--- /dev/null
+++ b/unittest.cpp
@@ -0,0 +1,39 @@
+#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("distinct positive numbers 2") {
+    double min = 0;
+    double max = 0;
+    std::vector<double>v{2,1};
+    CHECK(v.size() != 0);
+    CHECK(v.size() != 1);
+    find_minmax({1, 2}, min, max);
+    CHECK(min == 1);
+    CHECK(max == 2);
+    CHECK(min != max);
+}
+
+TEST_CASE("vector with one element") {
+    double min = 0;
+    double max = 0;
+    find_minmax({1}, min, max);
+    CHECK(min == 1);
+    CHECK(max == 1);
+}
+
+TEST_CASE("vector with same elements") {
+    double min = 0;
+    double max = 0;
+    find_minmax({2,2,2}, min, max);
+    CHECK(min == 2);
+    CHECK(max == 2);
+}