test(api): tighten lazy plan assertions and fix misplaced SHOW TABLES case

Move the SHOW TABLES case out of testNonQueryStatementsBlockedByParser
and into testNonQueryStatementsBlockedByWhitelist, where its error
message 'Only query statements are supported' actually belongs. The
parser accepts SHOW TABLES; the whitelist blocks it.

Replace trivial LogicalFilter / LogicalProject / LogicalAggregate
substring checks in UnifiedSqlSpecTest with assertions that prove the
specific feature under test: double-quoted string literal, MATCH as a
non-reserved function, GROUP BY ordinal resolution, boolean-to-integer
cast folding, and BABEL's string-to-integer coercion. Use AS aliases to
pin field names and avoid Calcite's EXPR$0 placeholders.

Signed-off-by: Chen Dai <daichen@amazon.com>

Author: dai-chen

api/src/test/java/org/opensearch/sql/api/UnifiedQueryPlannerSqlTest.java

@@ -237,6 +237,9 @@ public void testNonQueryStatementsBlockedByWhitelist() {
             MERGE INTO catalog.employees AS t
             USING (SELECT 99 AS id) AS s ON t.id = s.id
             WHEN MATCHED THEN UPDATE SET name = 'hacked'\
+            """,
+            """
+            SHOW TABLES\
             """)
         .forEach(
             sql ->
@@ -245,7 +248,6 @@ public void testNonQueryStatementsBlockedByWhitelist() {
 
   @Test
   public void testNonQueryStatementsBlockedByParser() {
-    // Babel parser rejects CREATE MATERIALIZED VIEW
     givenInvalidQuery(
             """
             CREATE MATERIALIZED VIEW mv AS
@@ -254,12 +256,5 @@ SELECT department, count(*)
             GROUP BY department\
             """)
         .assertErrorMessage("Encountered");
-
-    // Babel parser accepts SHOW TABLES but it's blocked by query-type whitelist
-    givenInvalidQuery(
-            """
-            SHOW TABLES\
-            """)
-        .assertErrorMessage("Only query statements are supported");
   }
 }

api/src/test/java/org/opensearch/sql/api/UnifiedSqlSpecTest.java

@@ -48,13 +48,14 @@ public void backtickQuotedIdentifiers() {
 
   @Test
   public void doubleQuotedStringLiteral() {
-    givenQuery("SELECT \"Hello\" FROM employees").assertPlanContains("LogicalProject");
+    givenQuery("SELECT \"Hello\" AS greeting FROM employees")
+        .assertPlanContains("LogicalProject(greeting=['Hello'])");
   }
 
   @Test
   public void matchNotReserved() {
     givenQuery("SELECT * FROM employees WHERE match(name, 'Hattie')")
-        .assertPlanContains("LogicalFilter");
+        .assertPlanContains("match(MAP('field', $1), MAP('query', 'Hattie'))");
   }
 
   @Test
@@ -80,18 +81,21 @@ public void groupByAlias() {
 
   @Test
   public void groupByOrdinal() {
-    givenQuery("SELECT name, COUNT(*) FROM employees GROUP BY 1")
-        .assertPlanContains("LogicalAggregate");
+    givenQuery("SELECT name, COUNT(*) AS cnt FROM employees GROUP BY 1")
+        .assertPlanContains("LogicalAggregate(group=[{0}], cnt=[COUNT()])")
+        .assertPlanContains("LogicalProject(name=[$1])");
   }
 
   @Test
   public void castBooleanToInteger() {
-    givenQuery("SELECT CAST(true AS INTEGER) FROM employees").assertPlanContains("LogicalProject");
+    givenQuery("SELECT CAST(true AS INTEGER) AS val FROM employees")
+        .assertPlanContains("LogicalProject(val=[1])");
   }
 
   @Test
   public void integerComparedToString() {
-    givenQuery("SELECT * FROM employees WHERE age > '30'").assertPlanContains("LogicalFilter");
+    givenQuery("SELECT * FROM employees WHERE age > '30'")
+        .assertPlanContains("condition=[>($2, CAST('30'):INTEGER NOT NULL)]");
   }
 
   @Test