diff --git a/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/DeleteSampleConfigurationActionTests.java b/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/DeleteSampleConfigurationActionTests.java
index 9727c82eb7178..ba9d4d656bcc4 100644
--- a/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/DeleteSampleConfigurationActionTests.java
+++ b/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/DeleteSampleConfigurationActionTests.java
@@ -47,7 +47,7 @@ protected DeleteSampleConfigurationAction.Request mutateInstance(DeleteSampleCon
                     instance.masterNodeTimeout(),
                     instance.ackTimeout()
                 );
-                String[] newIndices = randomValueOtherThan(instance.indices(), () -> new String[] { randomAlphaOfLength(10) });
+                String[] newIndices = randomArrayOtherThan(instance.indices(), () -> new String[] { randomAlphaOfLength(10) });
                 mutated.indices(newIndices);
                 yield mutated;
             }
diff --git a/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/PutSampleConfigurationActionTests.java b/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/PutSampleConfigurationActionTests.java
index ffe446a9cc2b0..a4fc1b91e491c 100644
--- a/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/PutSampleConfigurationActionTests.java
+++ b/server/src/test/java/org/elasticsearch/action/admin/indices/sampling/PutSampleConfigurationActionTests.java
@@ -55,7 +55,7 @@ protected PutSampleConfigurationAction.Request mutateInstance(PutSampleConfigura
                     instance.masterNodeTimeout(),
                     instance.ackTimeout()
                 );
-                mutated.indices(randomValueOtherThan(instance.indices(), () -> new String[] { randomAlphaOfLengthBetween(1, 10) }));
+                mutated.indices(randomArrayOtherThan(instance.indices(), () -> new String[] { randomAlphaOfLengthBetween(1, 10) }));
                 yield mutated;
             }
             default -> throw new IllegalStateException("Invalid mutation case");
diff --git a/server/src/test/java/org/elasticsearch/action/synonyms/PutSynonymsActionRequestSerializingTests.java b/server/src/test/java/org/elasticsearch/action/synonyms/PutSynonymsActionRequestSerializingTests.java
index ff9953fef595a..8af9bc9c6202b 100644
--- a/server/src/test/java/org/elasticsearch/action/synonyms/PutSynonymsActionRequestSerializingTests.java
+++ b/server/src/test/java/org/elasticsearch/action/synonyms/PutSynonymsActionRequestSerializingTests.java
@@ -14,8 +14,6 @@
 import org.elasticsearch.test.AbstractWireSerializingTestCase;
 
 import java.io.IOException;
-import java.util.Arrays;
-import java.util.List;
 
 import static org.elasticsearch.action.synonyms.SynonymsTestUtils.randomSynonymsSet;
 
@@ -34,14 +32,14 @@ protected PutSynonymsAction.Request createTestInstance() {
     @Override
     protected PutSynonymsAction.Request mutateInstance(PutSynonymsAction.Request instance) throws IOException {
         String synonymsSetId = instance.synonymsSetId();
-        List<SynonymRule> synonymRules = Arrays.asList(instance.synonymRules());
+        SynonymRule[] synonymRules = instance.synonymRules();
         boolean refresh = instance.refresh();
         switch (between(0, 2)) {
             case 0 -> synonymsSetId = randomValueOtherThan(synonymsSetId, () -> randomIdentifier());
-            case 1 -> synonymRules = randomValueOtherThan(synonymRules, () -> Arrays.asList(randomSynonymsSet()));
+            case 1 -> synonymRules = randomArrayOtherThan(synonymRules, () -> randomSynonymsSet());
             case 2 -> refresh = refresh == false;
             default -> throw new AssertionError("Illegal randomisation branch");
         }
-        return new PutSynonymsAction.Request(synonymsSetId, synonymRules.toArray(new SynonymRule[0]), refresh);
+        return new PutSynonymsAction.Request(synonymsSetId, synonymRules, refresh);
     }
 }
diff --git a/server/src/test/java/org/elasticsearch/search/vectors/KnnSearchBuilderTests.java b/server/src/test/java/org/elasticsearch/search/vectors/KnnSearchBuilderTests.java
index 7c0c4ba25300b..9f97fe7c861c7 100644
--- a/server/src/test/java/org/elasticsearch/search/vectors/KnnSearchBuilderTests.java
+++ b/server/src/test/java/org/elasticsearch/search/vectors/KnnSearchBuilderTests.java
@@ -126,7 +126,7 @@ yield new KnnSearchBuilder(
                 ).boost(instance.boost);
             }
             case 1 -> {
-                float[] newVector = randomValueOtherThan(instance.queryVector.asFloatVector(), () -> randomVector(5));
+                float[] newVector = randomArrayOtherThan(instance.queryVector.asFloatVector(), () -> randomVector(5));
                 yield new KnnSearchBuilder(
                     instance.field,
                     newVector,
diff --git a/test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java b/test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
index 8150456194b76..b8639c3c02064 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
@@ -1501,9 +1501,74 @@ public static <T> void maybeSet(Consumer<T> consumer, T value) {
      * helper to get a random value in a certain range that's different from the input
      */
     public static <T> T randomValueOtherThan(T input, Supplier<T> randomSupplier) {
+        assert input == null || input.getClass().isArray() == false
+            : "randomValueOtherThan() does not work as expected with arrays, use randomArrayOtherThan() instead";
         return randomValueOtherThanMany(v -> Objects.equals(input, v), randomSupplier);
     }
 
+    /**
+     * helper to get a random value in a certain range that's different from the input, for object arrays
+     */
+    public static <T> T[] randomArrayOtherThan(T[] input, Supplier<T[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for boolean arrays
+     */
+    public static boolean[] randomArrayOtherThan(boolean[] input, Supplier<boolean[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for byte arrays
+     */
+    public static byte[] randomArrayOtherThan(byte[] input, Supplier<byte[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for char arrays
+     */
+    public static char[] randomArrayOtherThan(char[] input, Supplier<char[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for short arrays
+     */
+    public static short[] randomArrayOtherThan(short[] input, Supplier<short[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for int arrays
+     */
+    public static int[] randomArrayOtherThan(int[] input, Supplier<int[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for long arrays
+     */
+    public static long[] randomArrayOtherThan(long[] input, Supplier<long[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for float arrays
+     */
+    public static float[] randomArrayOtherThan(float[] input, Supplier<float[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
+    /**
+     * helper to get a random value in a certain range that's different from the input, for double arrays
+     */
+    public static double[] randomArrayOtherThan(double[] input, Supplier<double[]> randomSupplier) {
+        return randomValueOtherThanMany(v -> Arrays.equals(input, v), randomSupplier);
+    }
+
     /**
      * helper to get a random value in a certain range that's different from the input
      */
diff --git a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/ClusterRequestTests.java b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/ClusterRequestTests.java
index b25fba6f1dc48..da54b327050bf 100644
--- a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/ClusterRequestTests.java
+++ b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/ClusterRequestTests.java
@@ -121,7 +121,7 @@ protected ClusterComputeRequest mutateInstance(ClusterComputeRequest in) throws
                     in.configuration(),
                     new RemoteClusterPlan(
                         plan.plan(),
-                        randomValueOtherThan(plan.targetIndices(), () -> generateRandomStringArray(10, 10, false, false)),
+                        randomArrayOtherThan(plan.targetIndices(), () -> generateRandomStringArray(10, 10, false, false)),
                         plan.originalIndices()
                     )
                 );
diff --git a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSerializationTests.java b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSerializationTests.java
index a9faac859f0da..267515b52c94f 100644
--- a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSerializationTests.java
+++ b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSerializationTests.java
@@ -243,7 +243,7 @@ protected DataNodeRequest mutateInstance(DataNodeRequest in) throws IOException
                 yield request;
             }
             case 7 -> {
-                var indices = randomValueOtherThan(in.indices(), () -> generateRandomStringArray(10, 10, false, false));
+                var indices = randomArrayOtherThan(in.indices(), () -> generateRandomStringArray(10, 10, false, false));
                 var request = new DataNodeRequest(
                     in.sessionId(),
                     in.configuration(),