diff --git a/test/unit_test_001.cpp b/test/unit_test_001.cpp
new file mode 100644
index 00000000..e095f456
--- /dev/null
+++ b/test/unit_test_001.cpp
@@ -0,0 +1,80 @@
+//
+//    FILE: unit_test_001.cpp
+//  AUTHOR: Rob Tillaart
+//    DATE: 2020-12-27
+// PURPOSE: unit tests for the MCP4725
+//          https://github.com/RobTillaart/MCP4725
+//          https://github.com/Arduino-CI/arduino_ci/blob/master/REFERENCE.md
+//
+
+// supported assertions
+// https://github.com/Arduino-CI/arduino_ci/blob/master/cpp/unittest/Assertion.h#L33-L42
+// ----------------------------
+// assertEqual(expected, actual)
+// assertNotEqual(expected, actual)
+// assertLess(expected, actual)
+// assertMore(expected, actual)
+// assertLessOrEqual(expected, actual)
+// assertMoreOrEqual(expected, actual)
+// assertTrue(actual)
+// assertFalse(actual)
+// assertNull(actual)
+// assertNotNull(actual)
+
+#include <ArduinoUnitTests.h>
+
+
+#include "Arduino.h"
+#include "RainGauge.h"
+#define TOLERANCE 0.11
+
+/**
+ * \example
+ * struct tm tm;
+ * time_t t;
+ * strptime("6 Dec 2001 12:33:45", "%d %b %Y %H:%M:%S", &tm);
+ * tm.tm_isdst = -1;      // Not set by strptime(); tells mktime()
+ *                        // to determine whether daylight saving time
+ *                        // is in effect
+ * t = mktime(&tm);
+ */
+
+static void setTime(const char *time, tm &tm, time_t &ts)
+{
+  strptime(time, "%Y-%m-%d %H:%M", &tm);
+  ts = mktime(&tm);
+}
+
+unittest_setup()
+{
+}
+
+
+unittest_teardown()
+{
+}
+
+
+unittest(test_constructor)
+{
+  RainGauge rainGauge;
+  rainGauge.reset();
+
+  tm        tm;
+  time_t    ts;
+  float     rainSensor;
+
+  fprintf(stderr, "test start\n");
+  printf("< RainHour >\n");
+  
+  setTime("2022-09-06 8:00", tm, ts);
+  rainGauge.update(tm, rainSensor=10.0);
+  assertEqualFloat(0, rainGauge.pastHour(), TOLERANCE);  
+
+}
+
+
+
+unittest_main()
+
+// --------