[SPARK-18685][TESTS] Fix URI and release resources after opening in tests at ExecutorClassLoaderSuite

## What changes were proposed in this pull request?

This PR fixes two problems as below:

- Close `BufferedSource` after `Source.fromInputStream(...)` to release resource and make the tests pass on Windows in `ExecutorClassLoaderSuite`

  ```
  [info] Exception encountered when attempting to run a suite with class name: org.apache.spark.repl.ExecutorClassLoaderSuite *** ABORTED *** (7 seconds, 333 milliseconds)
  [info]   java.io.IOException: Failed to delete: C:\projects\spark\target\tmp\spark-77b2f37b-6405-47c4-af1c-4a6a206511f2
  [info]   at org.apache.spark.util.Utils$.deleteRecursively(Utils.scala:1010)
  [info]   at org.apache.spark.repl.ExecutorClassLoaderSuite.afterAll(ExecutorClassLoaderSuite.scala:76)
  [info]   at org.scalatest.BeforeAndAfterAll$class.afterAll(BeforeAndAfterAll.scala:213)
  ...
  ```

- Fix URI correctly so that related tests can be passed on Windows.

  ```
  [info] - child first *** FAILED *** (78 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ...
  [info] - parent first *** FAILED *** (15 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ...
  [info] - child first can fall back *** FAILED *** (0 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ...
  [info] - child first can fail *** FAILED *** (0 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ...
  [info] - resource from parent *** FAILED *** (0 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ...
  [info] - resources from parent *** FAILED *** (0 milliseconds)
  [info]   java.net.URISyntaxException: Illegal character in authority at index 7: file://C:\projects\spark\target\tmp\spark-00b66070-0548-463c-b6f3-8965d173da9b
  [info]   at java.net.URI$Parser.fail(URI.java:2848)
  [info]   at java.net.URI$Parser.parseAuthority(URI.java:3186)
  ```

## How was this patch tested?

Manually tested via AppVeyor.

**Before**
https://ci.appveyor.com/project/spark-test/spark/build/102-rpel-ExecutorClassLoaderSuite

**After**
https://ci.appveyor.com/project/spark-test/spark/build/108-rpel-ExecutorClassLoaderSuite

Author: hyukjinkwon <[email protected]>

Closes apache#16116 from HyukjinKwon/close-after-open.

Author: HyukjinKwon

repl/src/test/scala/org/apache/spark/repl/ExecutorClassLoaderSuite.scala

@@ -24,7 +24,6 @@ import java.nio.charset.StandardCharsets
 import java.nio.file.{Paths, StandardOpenOption}
 import java.util
 
-import scala.concurrent.duration._
 import scala.io.Source
 import scala.language.implicitConversions
 
@@ -34,8 +33,6 @@ import org.mockito.Mockito._
 import org.mockito.invocation.InvocationOnMock
 import org.mockito.stubbing.Answer
 import org.scalatest.BeforeAndAfterAll
-import org.scalatest.concurrent.Interruptor
-import org.scalatest.concurrent.Timeouts._
 import org.scalatest.mock.MockitoSugar
 
 import org.apache.spark._
@@ -61,7 +58,7 @@ class ExecutorClassLoaderSuite
     super.beforeAll()
     tempDir1 = Utils.createTempDir()
     tempDir2 = Utils.createTempDir()
-    url1 = "file://" + tempDir1
+    url1 = tempDir1.toURI.toURL.toString
     urls2 = List(tempDir2.toURI.toURL).toArray
     childClassNames.foreach(TestUtils.createCompiledClass(_, tempDir1, "1"))
     parentResourceNames.foreach { x =>
@@ -118,8 +115,14 @@ class ExecutorClassLoaderSuite
     val resourceName: String = parentResourceNames.head
     val is = classLoader.getResourceAsStream(resourceName)
     assert(is != null, s"Resource $resourceName not found")
-    val content = Source.fromInputStream(is, "UTF-8").getLines().next()
-    assert(content.contains("resource"), "File doesn't contain 'resource'")
+
+    val bufferedSource = Source.fromInputStream(is, "UTF-8")
+    Utils.tryWithSafeFinally {
+      val content = bufferedSource.getLines().next()
+      assert(content.contains("resource"), "File doesn't contain 'resource'")
+    } {
+      bufferedSource.close()
+    }
   }
 
   test("resources from parent") {
@@ -128,8 +131,14 @@ class ExecutorClassLoaderSuite
     val resourceName: String = parentResourceNames.head
     val resources: util.Enumeration[URL] = classLoader.getResources(resourceName)
     assert(resources.hasMoreElements, s"Resource $resourceName not found")
-    val fileReader = Source.fromInputStream(resources.nextElement().openStream()).bufferedReader()
-    assert(fileReader.readLine().contains("resource"), "File doesn't contain 'resource'")
+
+    val bufferedSource = Source.fromInputStream(resources.nextElement().openStream())
+    Utils.tryWithSafeFinally {
+      val fileReader = bufferedSource.bufferedReader()
+      assert(fileReader.readLine().contains("resource"), "File doesn't contain 'resource'")
+    } {
+      bufferedSource.close()
+    }
   }
 
   test("fetch classes using Spark's RpcEnv") {