fix some tests

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

integ-test/src/test/java/org/opensearch/sql/security/CalciteCrossClusterSearchIT.java

@@ -240,6 +240,7 @@ public void testTimeBinCrossCluster() throws IOException {
         rows("2025-07-28 02:00:00", 9187));
   }
 
+  @Test
   public void testCrossClusterRegexBasic() throws IOException {
     JSONObject result =
         executeQuery(

ppl/src/main/java/org/opensearch/sql/ppl/utils/PPLQueryDataAnonymizer.java

@@ -428,11 +428,10 @@ public String visitRex(Rex node, String context) {
     StringBuilder command = new StringBuilder();
 
     // Build the base command
-    if (node.getMode() == Rex.RexMode.SED) {
-      command.append(String.format("%s | rex field=%s mode=sed %s", child, field, pattern));
-    } else {
-      command.append(String.format("%s | rex field=%s %s", child, field, pattern));
-    }
+    command.append(
+        String.format(
+            "%s | rex field=%s mode=%s %s",
+            child, field, node.getMode().toString().toLowerCase(), pattern));
 
     // Add optional parameters
     if (node.getMaxMatch().isPresent()) {

ppl/src/test/java/org/opensearch/sql/ppl/utils/PPLQueryDataAnonymizerTest.java

@@ -514,14 +514,15 @@ public void testPatterns() {
   @Test
   public void testRexCommand() {
     assertEquals(
-        "source=t | rex field=message \"(?<user>[A-Z]+)\"",
+        "source=t | rex field=message mode=extract \"(?<user>[A-Z]+)\"",
         anonymize("source=t | rex field=message \"(?<user>[A-Z]+)\""));
     assertEquals(
-        "source=t | rex field=lastname \"(?<initial>^[A-Z])\" | fields + lastname,initial",
+        "source=t | rex field=lastname mode=extract \"(?<initial>^[A-Z])\" | fields +"
+            + " lastname,initial",
         anonymize(
             "source=t | rex field=lastname \"(?<initial>^[A-Z])\" | fields lastname, initial"));
     assertEquals(
-        "source=t | rex field=name \"(?<first>[A-Z])\" max_match=3",
+        "source=t | rex field=name mode=extract \"(?<first>[A-Z])\" max_match=3",
         anonymize("source=t | rex field=name \"(?<first>[A-Z])\" max_match=3"));
   }
 
@@ -538,7 +539,7 @@ public void testRexSedMode() {
   @Test
   public void testRexWithOffsetField() {
     assertEquals(
-        "source=t | rex field=message \"(?<word>[a-z]+)\" offset_field=pos",
+        "source=t | rex field=message mode=extract \"(?<word>[a-z]+)\" offset_field=pos",
         anonymize("source=t | rex field=message \"(?<word>[a-z]+)\" offset_field=pos"));
   }