code: добавил параметр prompt

project/main.cpp

@@ -12,28 +12,30 @@ struct Input
     size_t bin_count{};
 };
 
-Input input_data()
+Input
+input_data(istream& in, bool prompt)
 {
     size_t number_count;
+    if (prompt)
     cerr << "Enter number count: ";
-    cin >> number_count;
+    in >> number_count;
 
-    Input in;
-    in.numbers.resize(number_count);
+    Input ik;
+    ik.numbers.resize(number_count);
     for (size_t i = 0; i < number_count; i++)
     {
-        cin >> in.numbers[i];
+        cin >> ik.numbers[i];
     }
     cerr << "Enter bin count: ";
-    cin>> in.bin_count;
-    return in;
+    cin>> ik.bin_count;
+    return ik;
 }
 
 
 
 int main()
 {
-    auto in = input_data();
+    auto in = input_data(cin, true);
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
     getch();