diff --git a/unittest.cpp b/unittest.cpp
index 0acaa65..3508c15 100644
--- a/unittest.cpp
+++ b/unittest.cpp
@@ -14,9 +14,7 @@ TEST_CASE("distinct positive numbers") {
 TEST_CASE("empty vector"){
     double min = 0;
     double max = 0;
-    find_minmax({ 0, 0 }, min, max);
-    CHECK(min == 0);
-    CHECK(max == 0);
+    CHECK(!find_minmax({}, min, max));
 }
 
 TEST_CASE("same elements"){
@@ -24,5 +22,20 @@ TEST_CASE("same elements"){
     double max = 0;
     find_minmax({ 1, 1 }, min, max);
     CHECK(min == max);
-    CHECK(max == min);
+}
+
+TEST_CASE("only one number"){
+    double min = 0;
+    double max = 0;
+    find_minmax({1}, min, max);
+    CHECK(min == 1);
+    CHECK(max == 1);
+}
+
+TEST_CASE("distinct negative numbers") {
+    double min = 0;
+    double max = 0;
+    find_minmax({-1, -2}, min, max);
+    CHECK(min == -2);
+    CHECK(max == -1);
 }