Added monotonicity unittest

Author: denizzzka

std/uuid.d

@@ -1452,6 +1452,7 @@ class MonotonicUUIDsFactory
     }
 }
 
+///
 unittest
 {
     import std.conv : to;
@@ -1503,6 +1504,26 @@ unittest
     }
 }
 
+///
+unittest
+{
+    import std.datetime.stopwatch;
+
+    auto f = new shared MonotonicUUIDsFactory;
+
+    UUID[100_000] uuids = void;
+
+    auto sw = StopWatch(AutoStart.yes); // for debugging purposes
+
+    foreach(ref u; uuids)
+        u = f.createUUIDv7_method3;
+
+    sw.stop;
+
+    foreach(i; 1 .. uuids.length)
+        assert(uuids[i-1].v7Timestamp_method3 < uuids[i].v7Timestamp_method3);
+}
+
 /**
  * This function returns a timestamp + random based UUID aka. uuid v7.
  */