[SPARK-38732][SQL][TESTS] Test the error class: INCOMPARABLE_PIVOT_COLUMN

### What changes were proposed in this pull request?

I add a test case for the error class INCOMPARABLE_PIVOT_COLUMN in the QueryExecutionErrorsSuite.

### Why are the changes needed?

To improve test coverage, and record expected error messages in tests.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

By existing tests.

Closes #36323 from lvshaokang/SPARK-38732.

Authored-by: lvshaokang <[email protected]>
Signed-off-by: Max Gekk <[email protected]>

Author: lvshaokang

sql/core/src/test/scala/org/apache/spark/sql/errors/QueryExecutionErrorsSuite.scala

@@ -22,7 +22,7 @@ import java.util.Locale
 import test.org.apache.spark.sql.connector.JavaSimpleWritableDataSource
 
 import org.apache.spark.{SparkArithmeticException, SparkException, SparkIllegalStateException, SparkRuntimeException, SparkUnsupportedOperationException, SparkUpgradeException}
-import org.apache.spark.sql.{DataFrame, QueryTest}
+import org.apache.spark.sql.{AnalysisException, DataFrame, QueryTest}
 import org.apache.spark.sql.catalyst.util.BadRecordException
 import org.apache.spark.sql.connector.SimpleWritableDataSource
 import org.apache.spark.sql.execution.QueryExecutionException
@@ -398,4 +398,30 @@ class QueryExecutionErrorsSuite
         "\\(QueryExecutionErrorsSuite\\$\\$Lambda\\$\\d+/\\w+: \\(string, int\\) => string\\)",
       matchMsg = true)
   }
+
+  test("INCOMPARABLE_PIVOT_COLUMN: an incomparable column of the map type") {
+    val e = intercept[AnalysisException] {
+      trainingSales
+      sql(
+        """
+          | select * from (
+          | select *,map(sales.course, sales.year) as map
+          | from trainingSales
+          | )
+          | pivot (
+          | sum(sales.earnings) as sum
+          | for map in (
+          | map("dotNET", 2012), map("JAVA", 2012),
+          | map("dotNet", 2013), map("Java", 2013)
+          | ))
+          |""".stripMargin).collect()
+    }
+    checkErrorClass(
+      exception = e,
+      errorClass = "INCOMPARABLE_PIVOT_COLUMN",
+      msg = "Invalid pivot column 'map.*\\'. Pivot columns must be comparable.",
+      sqlState = Some("42000"),
+      matchMsg = true
+    )
+  }
 }