diff --git a/main.cpp b/main.cpp
index e904c60..6c9aa03 100644
--- a/main.cpp
+++ b/main.cpp
@@ -10,25 +10,31 @@ struct Input {
     size_t bin_count;
 };
 
-Input input_data(istream& in) {
+Input input_data(istream& in, bool prompt) {
     Input inp;
     size_t number_count;
-    cerr << "Enter number count: ";
+    if (prompt){
+        cerr << "Enter number count: ";
+    }
     cin >> number_count;
 
     inp.numbers.resize(number_count);
-    cerr << "Enter numbers: ";
+    if (prompt){
+        cerr << "Enter numbers: ";
+    }
     for (size_t i = 0; i < number_count; i++) {
         cin >> inp.numbers[i];
     }
 
-    cerr << "Enter bin count: ";
+    if (prompt){
+        cerr << "Enter bin count: ";
+    }
     cin >> inp.bin_count;
     return inp;
 }
 
 int main() {
-    auto in = input_data(cin);
+    auto in = input_data(cin, true);
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
     return 0;
diff --git a/unittest.cpp b/unittest.cpp
new file mode 100644
index 0000000..bf37c5e
--- /dev/null
+++ b/unittest.cpp
@@ -0,0 +1,44 @@
+#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 negative numbers"){
+    double min = 0;
+    double max = 0;
+    find_minmax({-1, -2}, min, max);
+    CHECK(min == -2);
+    CHECK(max == -1);
+}
+TEST_CASE("vector of the same elements"){
+    double min = 0;
+    double max = 0;
+    find_minmax({3,3,3}, min, max);
+    CHECK(min == 3);
+    CHECK(max == 3);
+}
+
+TEST_CASE("single element vector") {
+    double min = 0;
+    double max = 0;
+    find_minmax({7}, min, max);
+    CHECK(min == 7);
+    CHECK(max == 7);
+}
+
+TEST_CASE("empty vector") {
+    double min = 0;
+    double max = 0;
+    find_minmax({}, min, max);
+    CHECK(min == 0);
+    CHECK(max == 0);
+}