diff --git a/unittest.cbp b/unittest.cbp
index 7f9621b..5a9c8c0 100644
--- a/unittest.cbp
+++ b/unittest.cbp
@@ -31,6 +31,10 @@
 		<Compiler>
 			<Add option="-Wall" />
 		</Compiler>
+		<Unit filename="doctest.h" />
+		<Unit filename="histogram.cpp" />
+		<Unit filename="histogram_internal.h" />
+		<Unit filename="unittest.cpp" />
 		<Extensions>
 			<lib_finder disable_auto="1" />
 		</Extensions>
diff --git a/unittest.cpp b/unittest.cpp
index 5ca2d51..dff5f08 100644
--- a/unittest.cpp
+++ b/unittest.cpp
@@ -10,3 +10,19 @@ TEST_CASE("distinct positive numbers") {
     CHECK(min == 1);
     CHECK(max == 1);
 }
+
+TEST_CASE("distinct negative numbers") {
+    double min = 0;
+    double max = 0;
+    find_minmax({-1,-100,-30,-40}, min, max);
+    CHECK(min == -100);
+    CHECK(max == -1);
+}
+
+TEST_CASE("vector of indentical elements") {
+    double min = 0;
+    double max = 0;
+    find_minmax({5,5,5,5}, min, max);
+    CHECK(min == 5);
+    CHECK(max == 5);
+}