[SPARK-34326][CORE][SQL] Fix UTs added in SPARK-31793 depending on the length of temp path

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

This PR proposes to fix the UTs being added in SPARK-31793, so that all things contributing the length limit are properly accounted.

### Why are the changes needed?

The test `DataSourceScanExecRedactionSuite.SPARK-31793: FileSourceScanExec metadata should contain limited file paths` is failing conditionally, depending on the length of the temp directory.

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

No.

### How was this patch tested?

Modified UTs explain the missing points, which also do the test.

Closes #31449 from HeartSaVioR/SPARK-34326-v2.

Authored-by: Jungtaek Lim (HeartSaVioR) <[email protected]>
Signed-off-by: Jungtaek Lim <[email protected]>

Author: HeartSaVioR

core/src/test/scala/org/apache/spark/util/UtilsSuite.scala

@@ -1308,6 +1308,12 @@ class UtilsSuite extends SparkFunSuite with ResetSystemProperties with Logging {
     assert(Utils.buildLocationMetadata(paths, 10) == "[path0, path1]")
     assert(Utils.buildLocationMetadata(paths, 15) == "[path0, path1, path2]")
     assert(Utils.buildLocationMetadata(paths, 25) == "[path0, path1, path2, path3]")
+
+    // edge-case: we should consider the fact non-path chars including '[' and ", " are accounted
+    // 1. second path is not added due to the addition of '['
+    assert(Utils.buildLocationMetadata(paths, 6) == "[path0]")
+    // 2. third path is not added due to the addition of ", "
+    assert(Utils.buildLocationMetadata(paths, 13) == "[path0, path1]")
   }
 
   test("checkHost supports both IPV4 and IPV6") {

sql/core/src/test/scala/org/apache/spark/sql/execution/DataSourceScanExecRedactionSuite.scala

@@ -19,6 +19,7 @@ package org.apache.spark.sql.execution
 import java.io.File
 
 import scala.collection.mutable
+import scala.util.Random
 
 import org.apache.hadoop.fs.Path
 
@@ -122,24 +123,39 @@ class DataSourceScanExecRedactionSuite extends DataSourceScanRedactionTest {
   test("SPARK-31793: FileSourceScanExec metadata should contain limited file paths") {
     withTempPath { path =>
       val dir = path.getCanonicalPath
+
+      // create a sub-directory with long name so that each root path will always exceed the limit
+      // this is to ensure we always test the case for the path truncation
+      val dataDirName = Random.alphanumeric.take(100).toList.mkString
+      val dataDir = new File(path, dataDirName)
+      dataDir.mkdir()
+
       val partitionCol = "partitionCol"
       spark.range(10)
         .select("id", "id")
         .toDF("value", partitionCol)
         .write
         .partitionBy(partitionCol)
-        .orc(dir)
-      val paths = (0 to 9).map(i => new File(dir, s"$partitionCol=$i").getCanonicalPath)
+        .orc(dataDir.getCanonicalPath)
+      val paths = (0 to 9).map(i => new File(dataDir, s"$partitionCol=$i").getCanonicalPath)
       val plan = spark.read.orc(paths: _*).queryExecution.executedPlan
       val location = plan collectFirst {
         case f: FileSourceScanExec => f.metadata("Location")
       }
       assert(location.isDefined)
       // The location metadata should at least contain one path
       assert(location.get.contains(paths.head))
-      // If the temp path length is larger than 100, the metadata length should not exceed
-      // twice of the length; otherwise, the metadata length should be controlled within 200.
-      assert(location.get.length < Math.max(paths.head.length, 100) * 2)
+
+      // The location metadata should have bracket wrapping paths
+      assert(location.get.indexOf('[') > -1)
+      assert(location.get.indexOf(']') > -1)
+
+      // extract paths in location metadata (removing classname, brackets, separators)
+      val pathsInLocation = location.get.substring(
+        location.get.indexOf('[') + 1, location.get.indexOf(']')).split(", ").toSeq
+
+      // the only one path should be available
+      assert(pathsInLocation.size == 1)
     }
   }
 }