[SPARK-20609][MLLIB][TEST] manually cleared 'spark.local.dir' before/after a...

[SPARK-20609][MLLIB][TEST] manually cleared 'spark.local.dir' before/after a test in ALSCleanerSuite

## What changes were proposed in this pull request?

This PR is similar to #17869.
Once` 'spark.local.dir'` is set. Unless this is manually cleared before/after a test. it could return the same directory even if this property is configured.
and add before/after for each likewise in ALSCleanerSuite.

## How was this patch tested?
existing test.

Author: caoxuewen <cao.xuewen@zte.com.cn>

Closes #18537 from heary-cao/ALSCleanerSuite.

mllib/src/test/scala/org/apache/spark/ml/recommendation/ALSSuite.scala

@@ -29,6 +29,7 @@ import scala.language.existentials
 import com.github.fommil.netlib.BLAS.{getInstance => blas}
 import org.apache.commons.io.FileUtils
 import org.apache.commons.io.filefilter.TrueFileFilter
+import org.scalatest.BeforeAndAfterEach
 
 import org.apache.spark._
 import org.apache.spark.internal.Logging
@@ -777,7 +778,20 @@ class ALSSuite
   }
 }
 
-class ALSCleanerSuite extends SparkFunSuite {
+class ALSCleanerSuite extends SparkFunSuite with BeforeAndAfterEach {
+  override def beforeEach(): Unit = {
+    super.beforeEach()
+    // Once `Utils.getOrCreateLocalRootDirs` is called, it is cached in `Utils.localRootDirs`.
+    // Unless this is manually cleared before and after a test, it returns the same directory
+    // set before even if 'spark.local.dir' is configured afterwards.
+    Utils.clearLocalRootDirs()
+  }
+
+  override def afterEach(): Unit = {
+    Utils.clearLocalRootDirs()
+    super.afterEach()
+  }
+
   test("ALS shuffle cleanup standalone") {
     val conf = new SparkConf()
     val localDir = Utils.createTempDir()