chore: use fixed seed in RNG in tests (#2917)

Author: andygrove

spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala

@@ -1773,7 +1773,7 @@ class CometExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelper {
   }
 
   test("Decimal random number tests") {
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     def makeNum(p: Int, s: Int): String = {
       val int1 = rand.nextLong()
       val int2 = rand.nextLong().abs

spark/src/test/scala/org/apache/comet/parquet/ParquetReadSuite.scala

@@ -348,7 +348,7 @@ abstract class ParquetReadSuite extends CometTestBase {
   }
 
   test("mixed nulls and non-nulls") {
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     val data = (0 to 100).map { i =>
       val row: (Boolean, Integer, java.lang.Long, java.lang.Float, java.lang.Double, String) = {
         if (rand.nextBoolean()) {
@@ -403,7 +403,7 @@ abstract class ParquetReadSuite extends CometTestBase {
         pageSize = pageSize,
         dictionaryPageSize = pageSize)
 
-      val rand = scala.util.Random
+      val rand = new scala.util.Random(42)
       val expected = (0 until n).map { i =>
         if (rand.nextBoolean()) {
           None
@@ -626,7 +626,7 @@ abstract class ParquetReadSuite extends CometTestBase {
         dictionaryPageSize = dictionaryPageSize,
         pageRowCountLimit = pageRowCount)
 
-      val rand = scala.util.Random
+      val rand = new scala.util.Random(42)
       val expected = (0 until n).map { i =>
         // use a single value for the first page, to make sure dictionary encoding kicks in
         val value = if (i < pageRowCount) i % 8 else i
@@ -814,7 +814,7 @@ abstract class ParquetReadSuite extends CometTestBase {
         dictionaryPageSize = pageSize,
         rowGroupSize = 1024 * 128)
 
-      val rand = scala.util.Random
+      val rand = new scala.util.Random(42)
       val expected = (0 until n).map { i =>
         if (rand.nextBoolean()) {
           None
@@ -1564,7 +1564,7 @@ abstract class ParquetReadSuite extends CometTestBase {
         pageSize = pageSize,
         dictionaryPageSize = pageSize)
 
-      val rand = scala.util.Random
+      val rand = new scala.util.Random(42)
       val expected = (0 until n).map { i =>
         if (rand.nextBoolean()) {
           None
@@ -1662,7 +1662,7 @@ abstract class ParquetReadSuite extends CometTestBase {
         dictionaryPageSize = dictionaryPageSize,
         pageRowCountLimit = pageRowCount)
 
-      val rand = scala.util.Random
+      val rand = new scala.util.Random(42)
       val expected = (0 until n).map { i =>
         // use a single value for the first page, to make sure dictionary encoding kicks in
         val value = if (i < pageRowCount) i % 8 else i

spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala

@@ -694,7 +694,7 @@ abstract class CometTestBase
 
     val idGenerator = new AtomicInteger(0)
 
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     val data = (begin until end).map { i =>
       if (nullEnabled && rand.nextBoolean()) {
         None
@@ -788,7 +788,7 @@ abstract class CometTestBase
       rowGroupSize = rowGroupSize)
     val div = if (dictionaryEnabled) 10 else n // maps value to a small range for dict to kick in
 
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     val expected = (0 until n).map { i =>
       if (rand.nextBoolean()) {
         None
@@ -842,7 +842,7 @@ abstract class CometTestBase
       rowGroupSize = rowGroupSize)
     val div = if (dictionaryEnabled) 10 else n // maps value to a small range for dict to kick in
 
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     val expected = (0 until n).map { i =>
       if (rand.nextBoolean()) {
         None
@@ -1240,7 +1240,7 @@ abstract class CometTestBase
     val schema = MessageTypeParser.parseMessageType(schemaStr)
     val writer = createParquetWriter(schema, path, dictionaryEnabled = true)
 
-    val rand = scala.util.Random
+    val rand = new scala.util.Random(42)
     val expected = (0 until total).map { i =>
       // use a single value for the first page, to make sure dictionary encoding kicks in
       if (rand.nextBoolean()) None