diff --git a/unittest.cpp b/unittest.cpp
new file mode 100644
index 0000000..4ff35e2
--- /dev/null
+++ b/unittest.cpp
@@ -0,0 +1,49 @@
+#define DOCTEST_CINFIG_NO_MULTITHREADING
+#define DOCTEST_CINFIG_IMOLEMENT_WITH_MAIN
+#include "doctest.h"
+#include "histogram_internal.h"
+#include "svg.h"
+#include <string>
+#include <fstream>
+
+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("check if vector is only one in length") {
+    double min = 3;
+    double max = 3;
+    find_minmax({ 3 }, min, max);
+    CHECK(min == 3);
+    CHECK(max == 3);
+}
+TEST_CASE("all numbers are the same") {
+    double min = 1;
+    double max = 1;
+    find_minmax({ 1, 1, 1, 1, 1, 1, 1, }, min, max);
+    CHECK(min == 1);
+    CHECK(max == 1);
+}
+TEST_CASE("all numbers are the same") {
+    double min = 0;
+    double max = 0;
+    CHECK(!find_minmax({}, min, max));
+}
+
+TEST_CASE("histogram for 10 variant is correct") {
+    std::fstream in, compare;
+    std::string line, compline;
+    bool flag = 0;
+    in.open("result.txt");
+    compare.open("compare.txt");
+    while (std::getline(in, line) && std::getline(compare, compline) && !flag) {
+        if (line != compline) {
+            flag = 1;
+        }
+    }
+    CHECK(flag == 0);
+}
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