[SPARK-39663][SQL][TESTS] Add UT for MysqlDialect listIndexes method

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/MySQLIntegrationSuite.scala

@@ -119,6 +119,8 @@ class MySQLIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JDBCTest
 
   override def supportsIndex: Boolean = true
 
+  override def supportListIndexes: Boolean = true
+
   override def indexOptions: String = "KEY_BLOCK_SIZE=10"
 
   testVarPop()

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/V2JDBCTest.scala

@@ -197,6 +197,8 @@ private[v2] trait V2JDBCTest extends SharedSparkSession with DockerIntegrationFu
 
   def supportsIndex: Boolean = false
 
+  def supportListIndexes: Boolean = false
+
   def indexOptions: String = ""
 
   test("SPARK-36895: Test INDEX Using SQL") {
@@ -219,11 +221,21 @@ private[v2] trait V2JDBCTest extends SharedSparkSession with DockerIntegrationFu
           s" The supported Index Types are:"))
 
         sql(s"CREATE index i1 ON $catalogName.new_table USING BTREE (col1)")
+        assert(jdbcTable.indexExists("i1"))
+        if (supportListIndexes) {
+          val indexes = jdbcTable.listIndexes()
+          assert(indexes.size == 1)
+          assert(indexes.head.indexName() == "i1")
+        }
+
         sql(s"CREATE index i2 ON $catalogName.new_table (col2, col3, col5)" +
           s" OPTIONS ($indexOptions)")
-
-        assert(jdbcTable.indexExists("i1") == true)
-        assert(jdbcTable.indexExists("i2") == true)
+        assert(jdbcTable.indexExists("i2"))
+        if (supportListIndexes) {
+          val indexes = jdbcTable.listIndexes()
+          assert(indexes.size == 2)
+          assert(indexes.map(_.indexName()).sorted === Array("i1", "i2"))
+        }
 
         // This should pass without exception
         sql(s"CREATE index IF NOT EXISTS i1 ON $catalogName.new_table (col1)")
@@ -234,10 +246,18 @@ private[v2] trait V2JDBCTest extends SharedSparkSession with DockerIntegrationFu
         assert(m.contains("Failed to create index i1 in new_table"))
 
         sql(s"DROP index i1 ON $catalogName.new_table")
-        sql(s"DROP index i2 ON $catalogName.new_table")
-
         assert(jdbcTable.indexExists("i1") == false)
+        if (supportListIndexes) {
+          val indexes = jdbcTable.listIndexes()
+          assert(indexes.size == 1)
+          assert(indexes.head.indexName() == "i2")
+        }
+
+        sql(s"DROP index i2 ON $catalogName.new_table")
         assert(jdbcTable.indexExists("i2") == false)
+        if (supportListIndexes) {
+          assert(jdbcTable.listIndexes().isEmpty)
+        }
 
         // This should pass without exception
         sql(s"DROP index IF EXISTS i1 ON $catalogName.new_table")

sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala

@@ -206,7 +206,7 @@ private case object MySQLDialect extends JdbcDialect with SQLConfHelper {
           val indexName = rs.getString("key_name")
           val colName = rs.getString("column_name")
           val indexType = rs.getString("index_type")
-          val indexComment = rs.getString("Index_comment")
+          val indexComment = rs.getString("index_comment")
           if (indexMap.contains(indexName)) {
             val index = indexMap.get(indexName).get
             val newIndex = new TableIndex(indexName, indexType,