Address comments.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala

@@ -40,7 +40,7 @@ abstract class Optimizer(sessionCatalog: SessionCatalog)
 
   // Check for structural integrity of the plan in test mode. Currently we only check if a plan is
   // still resolved after the execution of each rule.
-  override protected def planChecker(plan: LogicalPlan): Boolean = {
+  override protected def isPlanIntegral(plan: LogicalPlan): Boolean = {
     Utils.isTesting && plan.resolved
   }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/rules/RuleExecutor.scala

@@ -64,12 +64,12 @@ abstract class RuleExecutor[TreeType <: TreeNode[_]] extends Logging {
   protected def batches: Seq[Batch]
 
   /**
-   * Defines a check function which checks for structural integrity of the plan after the execution
+   * Defines a check function that checks for structural integrity of the plan after the execution
    * of each rule. For example, we can check whether a plan is still resolved after each rule in
-   * `Optimizer`, so we can catch rules that return invalid plans. The check function will returns
+   * `Optimizer`, so we can catch rules that return invalid plans. The check function returns
    * `false` if the given plan doesn't pass the structural integrity check.
    */
-  protected def planChecker(plan: TreeType): Boolean = true
+  protected def isPlanIntegral(plan: TreeType): Boolean = true
 
   /**
    * Executes the batches of rules defined by the subclass. The batches are executed serially
@@ -102,7 +102,7 @@ abstract class RuleExecutor[TreeType <: TreeNode[_]] extends Logging {
             }
 
             // Run the structural integrity checker against the plan after each rule.
-            if (!planChecker(result)) {
+            if (!isPlanIntegral(result)) {
               val message = s"After applying rule ${rule.ruleName} in batch ${batch.name}, " +
                 "the structural integrity of the plan is broken."
               throw new TreeNodeException(result, message, null)

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/OptimizerSICheckerSuite.scala → sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/OptimizerStructuralIntegrityCheckerSuite.scala

@@ -28,7 +28,7 @@ import org.apache.spark.sql.catalyst.rules._
 import org.apache.spark.sql.internal.SQLConf
 
 
-class OptimizerSICheckerkSuite extends PlanTest {
+class OptimizerStructuralIntegrityCheckerSuite extends PlanTest {
 
   object OptimizeRuleBreakSI extends Rule[LogicalPlan] {
     def apply(plan: LogicalPlan): LogicalPlan = plan transform {

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/trees/RuleExecutorSuite.scala

@@ -59,7 +59,7 @@ class RuleExecutorSuite extends SparkFunSuite {
 
   test("structural integrity checker") {
     object WithSIChecker extends RuleExecutor[Expression] {
-      override protected def planChecker(expr: Expression): Boolean = expr match {
+      override protected def isPlanIntegral(expr: Expression): Boolean = expr match {
         case IntegerLiteral(_) => true
         case _ => false
       }