diff --git a/doctest.h b/doctest.h
index c8535fa..5c754cd 100644
--- a/doctest.h
+++ b/doctest.h
@@ -1,6 +1,3 @@
-#ifndef DOCTEST_H_INCLUDED
-#define DOCTEST_H_INCLUDED
-
 // ====================================================================== lgtm [cpp/missing-header-guard]
 // == DO NOT MODIFY THIS FILE BY HAND - IT IS AUTO GENERATED BY CMAKE! ==
 // ======================================================================
@@ -7107,5 +7104,3 @@ DOCTEST_SUPPRESS_COMMON_WARNINGS_POP
 #undef NOMINMAX
 #undef DOCTEST_UNDEF_NOMINMAX
 #endif // DOCTEST_UNDEF_NOMINMAX
-
-#endif // DOCTEST_H_INCLUDED
diff --git a/unittest.cpp b/unittest.cpp
index a9ba7e5..7fb242b 100644
--- a/unittest.cpp
+++ b/unittest.cpp
@@ -10,3 +10,20 @@ TEST_CASE("distinct positive numbers") {
     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);
+}
+