diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableAddPartitionSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableAddPartitionSuiteBase.scala
index 1c1d802b991f..aa0668ccaaf5 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableAddPartitionSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableAddPartitionSuiteBase.scala
@@ -22,6 +22,20 @@ import org.apache.spark.sql.catalyst.analysis.PartitionsAlreadyExistException
 import org.apache.spark.sql.catalyst.catalog.CatalogTypes.TablePartitionSpec
 import org.apache.spark.sql.internal.SQLConf
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. ADD PARTITION` command that
+ * check V1 and V2 table catalogs. The tests that cannot run for all supported catalogs are
+ * located in more specific test suites:
+ *
+ *   - V2 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v2.AlterTableAddPartitionSuite`
+ *   - V1 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableAddPartitionSuiteBase`
+ *     - V1 In-Memory catalog:
+ *       `org.apache.spark.sql.execution.command.v1.AlterTableAddPartitionSuite`
+ *     - V1 Hive External catalog:
+ *       `org.apache.spark.sql.hive.execution.command.AlterTableAddPartitionSuite`
+ */
 trait AlterTableAddPartitionSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "ALTER TABLE .. ADD PARTITION"
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableDropPartitionSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableDropPartitionSuiteBase.scala
index 433f24c75083..cf8a1e9de5e0 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableDropPartitionSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableDropPartitionSuiteBase.scala
@@ -21,6 +21,20 @@ import org.apache.spark.sql.{AnalysisException, QueryTest}
 import org.apache.spark.sql.catalyst.analysis.NoSuchPartitionsException
 import org.apache.spark.sql.internal.SQLConf
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. DROP PARTITION` command that
+ * check V1 and V2 table catalogs. The tests that cannot run for all supported catalogs are
+ * located in more specific test suites:
+ *
+ *   - V2 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v2.AlterTableDropPartitionSuite`
+ *   - V1 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableDropPartitionSuiteBase`
+ *     - V1 In-Memory catalog:
+ *       `org.apache.spark.sql.execution.command.v1.AlterTableDropPartitionSuite`
+ *     - V1 Hive External catalog:
+ *       `org.apache.spark.sql.hive.execution.command.AlterTableDropPartitionSuite`
+ */
 trait AlterTableDropPartitionSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "ALTER TABLE .. DROP PARTITION"
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableRenamePartitionSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableRenamePartitionSuiteBase.scala
index a29cf6cabba4..40c167ce424a 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableRenamePartitionSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/AlterTableRenamePartitionSuiteBase.scala
@@ -19,6 +19,20 @@ package org.apache.spark.sql.execution.command
 
 import org.apache.spark.sql.QueryTest
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. RENAME PARTITION` command that
+ * check V1 and V2 table catalogs. The tests that cannot run for all supported catalogs are
+ * located in more specific test suites:
+ *
+ *   - V2 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v2.AlterTableRenamePartitionSuite`
+ *   - V1 table catalog tests:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableRenamePartitionSuiteBase`
+ *     - V1 In-Memory catalog:
+ *       `org.apache.spark.sql.execution.command.v1.AlterTableRenamePartitionSuite`
+ *     - V1 Hive External catalog:
+ *       `org.apache.spark.sql.hive.execution.command.AlterTableRenamePartitionSuite`
+ */
 trait AlterTableRenamePartitionSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "ALTER TABLE .. RENAME PARTITION"
 }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandTestUtils.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandTestUtils.scala
index 6ea2fea41f28..a613978ce375 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandTestUtils.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandTestUtils.scala
@@ -24,14 +24,26 @@ import org.apache.spark.sql.Row
 import org.apache.spark.sql.execution.datasources.PartitioningUtils
 import org.apache.spark.sql.test.SQLTestUtils
 
+/**
+ * The common settings and utility functions for all v1 and v2 test suites. When a function
+ * is not applicable to all supported catalogs, it should be placed to a specific trait:
+ *
+ *   - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.CommandSuiteBase`
+ *   - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.CommandSuiteBase`
+ *   - V2 In-Memory catalog: `org.apache.spark.sql.execution.command.v2.CommandSuiteBase`
+ */
 trait DDLCommandTestUtils extends SQLTestUtils {
   // The version of the catalog under testing such as "V1", "V2", "Hive V1".
   protected def version: String
   // Name of the command as SQL statement, for instance "SHOW PARTITIONS"
   protected def command: String
+  // The catalog name which can be used in SQL statements under testing
   protected def catalog: String
+  // The clause is used in creating tables for testing
   protected def defaultUsing: String
 
+  // Overrides the `test` method, and adds a prefix to easily find identify the catalog to which
+  // the failed test in logs belongs to.
   override def test(testName: String, testTags: Tag*)(testFun: => Any)
     (implicit pos: Position): Unit = {
     super.test(s"$command $version: " + testName, testTags: _*)(testFun)
@@ -49,6 +61,7 @@ trait DDLCommandTestUtils extends SQLTestUtils {
     }
   }
 
+  // Checks that the table `t` contains only the `expected` partitions.
   protected def checkPartitions(t: String, expected: Map[String, String]*): Unit = {
     val partitions = sql(s"SHOW PARTITIONS $t")
       .collect()
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DropTableSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DropTableSuiteBase.scala
index 9cba67f04a35..bb76bfd878f4 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DropTableSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DropTableSuiteBase.scala
@@ -19,6 +19,16 @@ package org.apache.spark.sql.execution.command
 
 import org.apache.spark.sql.{AnalysisException, QueryTest, Row}
 
+/**
+ * This base suite contains unified tests for the `DROP TABLE` command that check V1 and V2
+ * table catalogs. The tests that cannot run for all supported catalogs are located in more
+ * specific test suites:
+ *
+ *   - V2 table catalog tests: `org.apache.spark.sql.execution.command.v2.DropTableSuite`
+ *   - V1 table catalog tests: `org.apache.spark.sql.execution.command.v1.DropTableSuiteBase`
+ *     - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.DropTableSuite`
+ *     - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.DropTableSuite`
+ */
 trait DropTableSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "DROP TABLE"
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowPartitionsSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowPartitionsSuiteBase.scala
index 83808ab82d3b..9a942d348a18 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowPartitionsSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowPartitionsSuiteBase.scala
@@ -21,6 +21,17 @@ import org.apache.spark.sql.{AnalysisException, QueryTest, Row}
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.{StringType, StructType}
 
+/**
+ * This base suite contains unified tests for the `SHOW PARTITIONS` command that check V1 and V2
+ * table catalogs. The tests that cannot run for all supported catalogs are located in more
+ * specific test suites:
+ *
+ *   - V2 table catalog tests: `org.apache.spark.sql.execution.command.v2.ShowPartitionsSuite`
+ *   - V1 table catalog tests: `org.apache.spark.sql.execution.command.v1.ShowPartitionsSuiteBase`
+ *     - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.ShowPartitionsSuite`
+ *     - V1 Hive External catalog:
+ *       `org.apache.spark.sql.hive.execution.command.ShowPartitionsSuite`
+ */
 trait ShowPartitionsSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "SHOW PARTITIONS"
   // Gets the schema of `SHOW PARTITIONS`
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowTablesSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowTablesSuiteBase.scala
index 5b729a4eb1c8..6a1337ef5ac8 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowTablesSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/ShowTablesSuiteBase.scala
@@ -23,6 +23,16 @@ import org.apache.spark.sql.connector.catalog.CatalogV2Implicits._
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.StructType
 
+/**
+ * This base suite contains unified tests for the `SHOW TABLES` command that check V1 and V2
+ * table catalogs. The tests that cannot run for all supported catalogs are located in more
+ * specific test suites:
+ *
+ *   - V2 table catalog tests: `org.apache.spark.sql.execution.command.v2.ShowTablesSuite`
+ *   - V1 table catalog tests: `org.apache.spark.sql.execution.command.v1.ShowTablesSuiteBase`
+ *     - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.ShowTablesSuite`
+ *     - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.ShowTablesSuite`
+ */
 trait ShowTablesSuiteBase extends QueryTest with DDLCommandTestUtils {
   override val command = "SHOW TABLES"
   protected def defaultNamespace: Seq[String]
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableAddPartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableAddPartitionSuite.scala
index a749b1e3dd14..808eab834052 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableAddPartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableAddPartitionSuite.scala
@@ -21,6 +21,16 @@ import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.catalog.CatalogTypes.TablePartitionSpec
 import org.apache.spark.sql.execution.command
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. ADD PARTITION` command that
+ * check V1 table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableAddPartitionSuite`
+ *   - V1 Hive External catalog:
+ *     `org.apache.spark.sql.hive.execution.command.AlterTableAddPartitionSuite`
+ */
 trait AlterTableAddPartitionSuiteBase extends command.AlterTableAddPartitionSuiteBase {
   override protected def checkLocation(
       t: String,
@@ -49,4 +59,8 @@ trait AlterTableAddPartitionSuiteBase extends command.AlterTableAddPartitionSuit
   }
 }
 
+/**
+ * The class contains tests for the `ALTER TABLE .. ADD PARTITION` command to check
+ * V1 In-Memory table catalog.
+ */
 class AlterTableAddPartitionSuite extends AlterTableAddPartitionSuiteBase with CommandSuiteBase
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableDropPartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableDropPartitionSuite.scala
index 71032eefee2b..a6490ebdb950 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableDropPartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableDropPartitionSuite.scala
@@ -20,6 +20,16 @@ package org.apache.spark.sql.execution.command.v1
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.execution.command
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. DROP PARTITION` command that
+ * check V1 table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableDropPartitionSuite`
+ *   - V1 Hive External catalog:
+ *     `org.apache.spark.sql.hive.execution.command.AlterTableDropPartitionSuite`
+ */
 trait AlterTableDropPartitionSuiteBase extends command.AlterTableDropPartitionSuiteBase {
   override protected val notFullPartitionSpecErr = "The following partitions not found in table"
 
@@ -34,6 +44,10 @@ trait AlterTableDropPartitionSuiteBase extends command.AlterTableDropPartitionSu
   }
 }
 
+/**
+ * The class contains tests for the `ALTER TABLE .. DROP PARTITION` command to check
+ * V1 In-Memory table catalog.
+ */
 class AlterTableDropPartitionSuite
   extends AlterTableDropPartitionSuiteBase
   with CommandSuiteBase {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableRenamePartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableRenamePartitionSuite.scala
index 89d5e5f4635d..d923886fbdb9 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableRenamePartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/AlterTableRenamePartitionSuite.scala
@@ -22,6 +22,16 @@ import org.apache.spark.sql.catalyst.analysis.{NoSuchPartitionException, Partiti
 import org.apache.spark.sql.execution.command
 import org.apache.spark.sql.internal.SQLConf
 
+/**
+ * This base suite contains unified tests for the `ALTER TABLE .. RENAME PARTITION` command that
+ * check V1 table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog:
+ *     `org.apache.spark.sql.execution.command.v1.AlterTableRenamePartitionSuite`
+ *   - V1 Hive External catalog:
+ *     `org.apache.spark.sql.hive.execution.command.AlterTableRenamePartitionSuite`
+ */
 trait AlterTableRenamePartitionSuiteBase extends command.AlterTableRenamePartitionSuiteBase {
   protected def createSinglePartTable(t: String): Unit = {
     sql(s"CREATE TABLE $t (id bigint, data string) $defaultUsing PARTITIONED BY (id)")
@@ -164,6 +174,10 @@ trait AlterTableRenamePartitionSuiteBase extends command.AlterTableRenamePartiti
   }
 }
 
+/**
+ * The class contains tests for the `ALTER TABLE .. RENAME PARTITION` command to check
+ * V1 In-Memory table catalog.
+ */
 class AlterTableRenamePartitionSuite
   extends AlterTableRenamePartitionSuiteBase
   with CommandSuiteBase
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/CommandSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/CommandSuiteBase.scala
index 323f9c9365a1..c4ecf1c98bb6 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/CommandSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/CommandSuiteBase.scala
@@ -20,8 +20,14 @@ package org.apache.spark.sql.execution.command.v1
 import org.apache.spark.sql.connector.catalog.CatalogManager
 import org.apache.spark.sql.test.SharedSparkSession
 
+/**
+ * The trait contains settings and utility functions. It can be mixed to the test suites for
+ * datasource v1 In-Memory catalog. This trait complements the common trait
+ * `org.apache.spark.sql.execution.command.DDLCommandTestUtils` with utility functions and
+ * settings for all unified datasource V1 and V2 test suites.
+ */
 trait CommandSuiteBase extends SharedSparkSession {
-  def version: String = "V1"
+  def version: String = "V1" // The prefix is added to test names
   def catalog: String = CatalogManager.SESSION_CATALOG_NAME
-  def defaultUsing: String = "USING parquet"
+  def defaultUsing: String = "USING parquet" // The clause is used in creating tables under testing
 }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/DropTableSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/DropTableSuite.scala
index 530d18cb6f7b..497624f0a18d 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/DropTableSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/DropTableSuite.scala
@@ -19,6 +19,14 @@ package org.apache.spark.sql.execution.command.v1
 
 import org.apache.spark.sql.execution.command
 
+/**
+ * This base suite contains unified tests for the `DROP TABLE` command that check V1
+ * table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.DropTableSuite`
+ *   - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.DropTableSuite`
+ */
 trait DropTableSuiteBase extends command.DropTableSuiteBase {
   test("purge option") {
     withNamespace(s"$catalog.ns") {
@@ -33,5 +41,8 @@ trait DropTableSuiteBase extends command.DropTableSuiteBase {
   }
 }
 
+/**
+ * The class contains tests for the `DROP TABLE` command to check V1 In-Memory table catalog.
+ */
 class DropTableSuite extends DropTableSuiteBase with CommandSuiteBase
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowPartitionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowPartitionsSuite.scala
index 5d992d18890e..5be5e28d0170 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowPartitionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowPartitionsSuite.scala
@@ -20,6 +20,14 @@ package org.apache.spark.sql.execution.command.v1
 import org.apache.spark.sql.{AnalysisException, Row, SaveMode}
 import org.apache.spark.sql.execution.command
 
+/**
+ * This base suite contains unified tests for the `SHOW PARTITIONS` command that check V1
+ * table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.ShowPartitionsSuite`
+ *   - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.ShowPartitionsSuite`
+ */
 trait ShowPartitionsSuiteBase extends command.ShowPartitionsSuiteBase {
   test("show everything in the default database") {
     val table = "dateTable"
@@ -63,6 +71,9 @@ trait ShowPartitionsSuiteBase extends command.ShowPartitionsSuiteBase {
   }
 }
 
+/**
+ * The class contains tests for the `SHOW PARTITIONS` command to check V1 In-Memory table catalog.
+ */
 class ShowPartitionsSuite extends ShowPartitionsSuiteBase with CommandSuiteBase {
   // The test is placed here because it fails with `USING HIVE`:
   // org.apache.spark.sql.AnalysisException:
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowTablesSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowTablesSuite.scala
index 12b4df269e15..2cf50b7ddf25 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowTablesSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/ShowTablesSuite.scala
@@ -22,6 +22,14 @@ import org.apache.spark.sql.execution.command
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.{BooleanType, StringType, StructType}
 
+/**
+ * This base suite contains unified tests for the `SHOW TABLES` command that check V1
+ * table catalogs. The tests that cannot run for all V1 catalogs are located in more
+ * specific test suites:
+ *
+ *   - V1 In-Memory catalog: `org.apache.spark.sql.execution.command.v1.ShowTablesSuite`
+ *   - V1 Hive External catalog: `org.apache.spark.sql.hive.execution.command.ShowTablesSuite`
+ */
 trait ShowTablesSuiteBase extends command.ShowTablesSuiteBase {
   override def defaultNamespace: Seq[String] = Seq("default")
   override def showSchema: StructType = {
@@ -102,6 +110,9 @@ trait ShowTablesSuiteBase extends command.ShowTablesSuiteBase {
   }
 }
 
+/**
+ * The class contains tests for the `SHOW TABLES` command to check V1 In-Memory table catalog.
+ */
 class ShowTablesSuite extends ShowTablesSuiteBase with CommandSuiteBase {
   test("SPARK-33670: show partitions from a datasource table") {
     import testImplicits._
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableAddPartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableAddPartitionSuite.scala
index b0d0f6ced934..0f0f8fa38932 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableAddPartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableAddPartitionSuite.scala
@@ -24,6 +24,10 @@ import org.apache.spark.sql.connector.InMemoryPartitionTable
 import org.apache.spark.sql.connector.catalog.{CatalogV2Implicits, Identifier}
 import org.apache.spark.sql.execution.command
 
+/**
+ * The class contains tests for the `ALTER TABLE .. ADD PARTITION` command
+ * to check V2 table catalogs.
+ */
 class AlterTableAddPartitionSuite
   extends command.AlterTableAddPartitionSuiteBase
   with CommandSuiteBase {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableDropPartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableDropPartitionSuite.scala
index 97ef10e25651..d6890d6faef7 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableDropPartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableDropPartitionSuite.scala
@@ -20,6 +20,10 @@ package org.apache.spark.sql.execution.command.v2
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.execution.command
 
+/**
+ * The class contains tests for the `ALTER TABLE .. DROP PARTITION` command
+ * to check V2 table catalogs.
+ */
 class AlterTableDropPartitionSuite
   extends command.AlterTableDropPartitionSuiteBase
   with CommandSuiteBase {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableRenamePartitionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableRenamePartitionSuite.scala
index 026f1dcc33a1..d1c252adde36 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableRenamePartitionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/AlterTableRenamePartitionSuite.scala
@@ -20,6 +20,10 @@ package org.apache.spark.sql.execution.command.v2
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.execution.command
 
+/**
+ * The class contains tests for the `ALTER TABLE .. RENAME PARTITION` command
+ * to check V2 table catalogs.
+ */
 class AlterTableRenamePartitionSuite
   extends command.AlterTableRenamePartitionSuiteBase
   with CommandSuiteBase {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/CommandSuiteBase.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/CommandSuiteBase.scala
index b1f6a5b318a3..0978126f27fd 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/CommandSuiteBase.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/CommandSuiteBase.scala
@@ -21,11 +21,18 @@ import org.apache.spark.SparkConf
 import org.apache.spark.sql.connector.{InMemoryPartitionTableCatalog, InMemoryTableCatalog}
 import org.apache.spark.sql.test.SharedSparkSession
 
+/**
+ * The trait contains settings and utility functions. It can be mixed to the test suites for
+ * datasource v2 catalogs (in-memory test catalogs). This trait complements the trait
+ * `org.apache.spark.sql.execution.command.DDLCommandTestUtils` with common utility functions
+ * for all unified datasource V1 and V2 test suites.
+ */
 trait CommandSuiteBase extends SharedSparkSession {
-  def version: String = "V2"
-  def catalog: String = "test_catalog"
-  def defaultUsing: String = "USING _"
+  def version: String = "V2" // The prefix is added to test names
+  def catalog: String = "test_catalog" // The default V2 catalog for testing
+  def defaultUsing: String = "USING _" // The clause is used in creating v2 tables under testing
 
+  // V2 catalogs created and used especially for testing
   override def sparkConf: SparkConf = super.sparkConf
     .set(s"spark.sql.catalog.$catalog", classOf[InMemoryPartitionTableCatalog].getName)
     .set(s"spark.sql.catalog.non_part_$catalog", classOf[InMemoryTableCatalog].getName)
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/DropTableSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/DropTableSuite.scala
index a272f649288f..9c9b7d3049c7 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/DropTableSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/DropTableSuite.scala
@@ -22,6 +22,9 @@ import org.apache.spark.sql.connector.InMemoryTableSessionCatalog
 import org.apache.spark.sql.execution.command
 import org.apache.spark.sql.internal.SQLConf.V2_SESSION_CATALOG_IMPLEMENTATION
 
+/**
+ * The class contains tests for the `DROP TABLE` command to check V2 table catalogs.
+ */
 class DropTableSuite extends command.DropTableSuiteBase with CommandSuiteBase {
   test("purge option") {
     withNamespaceAndTable("ns", "tbl") { t =>
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowPartitionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowPartitionsSuite.scala
index 431f64baf4b7..44d8b57ce159 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowPartitionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowPartitionsSuite.scala
@@ -20,6 +20,9 @@ package org.apache.spark.sql.execution.command.v2
 import org.apache.spark.sql.{AnalysisException, Row, SaveMode}
 import org.apache.spark.sql.execution.command
 
+/**
+ * The class contains tests for the `SHOW PARTITIONS` command to check V2 table catalogs.
+ */
 class ShowPartitionsSuite extends command.ShowPartitionsSuiteBase with CommandSuiteBase {
   test("a table does not support partitioning") {
     val table = s"non_part_$catalog.tab1"
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowTablesSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowTablesSuite.scala
index cef5eac703ee..6a9a9399b956 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowTablesSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/v2/ShowTablesSuite.scala
@@ -21,6 +21,9 @@ import org.apache.spark.sql.{AnalysisException, Row}
 import org.apache.spark.sql.execution.command
 import org.apache.spark.sql.types.{StringType, StructType}
 
+/**
+ * The class contains tests for the `SHOW TABLES` command to check V2 table catalogs.
+ */
 class ShowTablesSuite extends command.ShowTablesSuiteBase with CommandSuiteBase {
   override def defaultNamespace: Seq[String] = Nil
   override def showSchema: StructType = {
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableAddPartitionSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableAddPartitionSuite.scala
index 2a996c3f4690..f8fe23f643cd 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableAddPartitionSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableAddPartitionSuite.scala
@@ -19,6 +19,10 @@ package org.apache.spark.sql.hive.execution.command
 
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `ALTER TABLE .. ADD PARTITION` command to check
+ * V1 Hive external table catalog.
+ */
 class AlterTableAddPartitionSuite
     extends v1.AlterTableAddPartitionSuiteBase
     with CommandSuiteBase
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableDropPartitionSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableDropPartitionSuite.scala
index a4f9ab0b0433..5cac27f0d254 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableDropPartitionSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableDropPartitionSuite.scala
@@ -19,6 +19,10 @@ package org.apache.spark.sql.hive.execution.command
 
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `ALTER TABLE .. DROP PARTITION` command to check
+ * V1 Hive external table catalog.
+ */
 class AlterTableDropPartitionSuite
   extends v1.AlterTableDropPartitionSuiteBase
   with CommandSuiteBase
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableRenamePartitionSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableRenamePartitionSuite.scala
index 86edab74ab99..5cd5122a2a7f 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableRenamePartitionSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/AlterTableRenamePartitionSuite.scala
@@ -19,6 +19,10 @@ package org.apache.spark.sql.hive.execution.command
 
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `ALTER TABLE .. RENAME PARTITION` command to check
+ * V1 Hive external table catalog.
+ */
 class AlterTableRenamePartitionSuite
   extends v1.AlterTableRenamePartitionSuiteBase
   with CommandSuiteBase
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/CommandSuiteBase.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/CommandSuiteBase.scala
index 3f603fd6c7dd..39b4be61449c 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/CommandSuiteBase.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/CommandSuiteBase.scala
@@ -20,8 +20,14 @@ package org.apache.spark.sql.hive.execution.command
 import org.apache.spark.sql.connector.catalog.CatalogManager
 import org.apache.spark.sql.hive.test.TestHiveSingleton
 
+/**
+ * The trait contains settings and utility functions. It can be mixed to the test suites for
+ * datasource v1 Hive external catalog. This trait complements the common trait
+ * `org.apache.spark.sql.execution.command.DDLCommandTestUtils` with utility functions and
+ * settings for all unified datasource V1 and V2 test suites.
+ */
 trait CommandSuiteBase extends TestHiveSingleton {
-  def version: String = "Hive V1"
+  def version: String = "Hive V1" // The prefix is added to test names
   def catalog: String = CatalogManager.SESSION_CATALOG_NAME
-  def defaultUsing: String = "USING HIVE"
+  def defaultUsing: String = "USING HIVE" // The clause is used in creating tables under testing
 }
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/DropTableSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/DropTableSuite.scala
index b2a404d7206a..c1f17d128064 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/DropTableSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/DropTableSuite.scala
@@ -19,4 +19,7 @@ package org.apache.spark.sql.hive.execution.command
 
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `DROP TABLE` command to check V1 Hive external table catalog.
+ */
 class DropTableSuite extends v1.DropTableSuiteBase with CommandSuiteBase
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowPartitionsSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowPartitionsSuite.scala
index eaac8f5e8146..904c6c40b938 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowPartitionsSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowPartitionsSuite.scala
@@ -20,6 +20,10 @@ package org.apache.spark.sql.hive.execution.command
 import org.apache.spark.sql.{Row, SaveMode}
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `SHOW PARTITIONS` command to check
+ * V1 Hive external table catalog.
+ */
 class ShowPartitionsSuite extends v1.ShowPartitionsSuiteBase with CommandSuiteBase {
   test("null and empty string as partition values") {
     import testImplicits._
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowTablesSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowTablesSuite.scala
index 8c00b3fe7f7c..7b3652a86034 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowTablesSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/ShowTablesSuite.scala
@@ -19,4 +19,7 @@ package org.apache.spark.sql.hive.execution.command
 
 import org.apache.spark.sql.execution.command.v1
 
+/**
+ * The class contains tests for the `SHOW TABLES` command to check V1 Hive external table catalog.
+ */
 class ShowTablesSuite extends v1.ShowTablesSuiteBase with CommandSuiteBase