Fix and simplify DataStreamLifecycleTests & DataStreamLifecycleTemplateTests

Author: gmarouli

server/src/test/java/org/elasticsearch/cluster/metadata/DataStreamLifecycleTemplateTests.java

@@ -63,14 +63,16 @@ protected DataStreamLifecycle.Template mutateInstance(DataStreamLifecycle.Templa
                 downsamplingRounds = randomValueOtherThan(downsamplingRounds, DataStreamLifecycleTemplateTests::randomDownsamplingRounds);
                 if (downsamplingRounds.get() != null) {
                     lifecycleTarget = DataStreamLifecycle.LifecycleType.DATA;
+                } else {
+                    downsamplingMethod = ResettableValue.undefined();
                 }
             }
             case 4 -> {
-                if (downsamplingRounds.get() == null) {
+                downsamplingMethod = randomValueOtherThan(downsamplingMethod, DataStreamLifecycleTemplateTests::randomDownsamplingMethod);
+                if (downsamplingMethod.get() != null && downsamplingRounds.get() == null) {
                     downsamplingRounds = ResettableValue.create(DataStreamLifecycleTests.randomDownsamplingRounds());
                     lifecycleTarget = DataStreamLifecycle.LifecycleType.DATA;
                 }
-                downsamplingMethod = randomValueOtherThan(downsamplingMethod, DataStreamLifecycleTemplateTests::randomDownsamplingMethod);
             }
             default -> throw new AssertionError("Illegal randomisation branch");
         }
@@ -219,7 +221,7 @@ public static DataStreamLifecycle.Template randomDataLifecycleTemplate() {
             downsamplingRounds,
             downsamplingRounds.get() == null
                 ? randomBoolean() ? ResettableValue.undefined() : ResettableValue.reset()
-                : ResettableValue.undefined()
+                : randomDownsamplingMethod()
         );
     }
 

server/src/test/java/org/elasticsearch/cluster/metadata/DataStreamLifecycleTests.java

@@ -12,7 +12,6 @@
 import org.elasticsearch.action.admin.indices.rollover.RolloverConditions;
 import org.elasticsearch.action.admin.indices.rollover.RolloverConfiguration;
 import org.elasticsearch.action.admin.indices.rollover.RolloverConfigurationTests;
-import org.elasticsearch.action.downsample.DownsampleConfig;
 import org.elasticsearch.action.downsample.DownsampleConfigTests;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -100,18 +99,12 @@ protected DataStreamLifecycle mutateInstance(DataStreamLifecycle instance) throw
                 }
             }
             case 3 -> {
-                // We need to enable downsampling in order to add a non value downsampling method
-                if (downsamplingRounds == null) {
+                // We need to enable downsampling in order to add a non-value downsampling method
+                downsamplingMethod = randomValueOtherThan(downsamplingMethod, DownsampleConfigTests::randomSamplingMethod);
+                if (downsamplingMethod != null && downsamplingRounds == null) {
                     downsamplingRounds = randomDownsamplingRounds();
                     lifecycleTarget = DataStreamLifecycle.LifecycleType.DATA;
                 }
-                if (downsamplingMethod == null) {
-                    downsamplingMethod = randomFrom(DownsampleConfig.SamplingMethod.values());
-                } else if (downsamplingMethod == DownsampleConfig.SamplingMethod.AGGREGATE) {
-                    downsamplingMethod = randomBoolean() ? null : DownsampleConfig.SamplingMethod.LAST_VALUE;
-                } else {
-                    downsamplingMethod = randomBoolean() ? null : DownsampleConfig.SamplingMethod.AGGREGATE;
-                }
             }
             default -> enabled = enabled == false;
         }