Add missing tests to Dynatrace types (#3626)

Author: pirgeo

implementations/micrometer-registry-dynatrace/src/test/java/io/micrometer/dynatrace/types/DynatraceDistributionSummaryTest.java

@@ -66,6 +66,24 @@ void testDynatraceDistributionSummaryValuesAreRecorded() {
         assertMinMaxSumCount(ds, 3.14, 4.76, 7.9, 2);
     }
 
+    @Test
+    void testDynatraceDistributionSummary_NegativeValuesAreIgnored() {
+        DynatraceDistributionSummary ds = new DynatraceDistributionSummary(ID, CLOCK, DISTRIBUTION_STATISTIC_CONFIG, 1);
+        ds.record(-1.23);
+        ds.record(-100.3);
+
+        assertMinMaxSumCount(ds, 0., 0., 0., 0);
+    }
+
+    @Test
+    void testDynatraceDistributionSummary_NaNValuesAreIgnored() {
+        DynatraceDistributionSummary ds = new DynatraceDistributionSummary(ID, CLOCK, DISTRIBUTION_STATISTIC_CONFIG, 1);
+
+        ds.record(Double.NaN);
+
+        assertMinMaxSumCount(ds, 0., 0., 0., 0);
+    }
+
     @Test
     void testDynatraceDistributionSummaryScaled() {
         double scale = 1.5;