[SPARK-22940][SQL] HiveExternalCatalogVersionsSuite should succeed on…

… platforms that don't have wget

## What changes were proposed in this pull request?

Modified HiveExternalCatalogVersionsSuite.scala to use Utils.doFetchFile to download different versions of Spark binaries rather than launching wget as an external process.

On platforms that don't have wget installed, this suite fails with an error.

cloud-fan : would you like to check this change?

## How was this patch tested?

1) test-only of HiveExternalCatalogVersionsSuite on several platforms. Tested bad mirror, read timeout, and redirects.
2) ./dev/run-tests

Author: Bruce Robbins <bersprockets@gmail.com>

Closes #20147 from bersprockets/SPARK-22940-alt.

sql/hive/src/test/scala/org/apache/spark/sql/hive/HiveExternalCatalogVersionsSuite.scala

@@ -18,11 +18,14 @@
 package org.apache.spark.sql.hive
 
 import java.io.File
-import java.nio.file.Files
+import java.nio.charset.StandardCharsets
+import java.nio.file.{Files, Paths}
 
 import scala.sys.process._
 
-import org.apache.spark.TestUtils
+import org.apache.hadoop.conf.Configuration
+
+import org.apache.spark.{SecurityManager, SparkConf, TestUtils}
 import org.apache.spark.sql.{QueryTest, Row, SparkSession}
 import org.apache.spark.sql.catalyst.TableIdentifier
 import org.apache.spark.sql.catalyst.catalog.CatalogTableType
@@ -55,14 +58,19 @@ class HiveExternalCatalogVersionsSuite extends SparkSubmitTestUtils {
   private def tryDownloadSpark(version: String, path: String): Unit = {
     // Try mirrors a few times until one succeeds
     for (i <- 0 until 3) {
+      // we don't retry on a failure to get mirror url. If we can't get a mirror url,
+      // the test fails (getStringFromUrl will throw an exception)
       val preferredMirror =
-        Seq("wget", "https://www.apache.org/dyn/closer.lua?preferred=true", "-q", "-O", "-").!!.trim
-      val url = s"$preferredMirror/spark/spark-$version/spark-$version-bin-hadoop2.7.tgz"
+        getStringFromUrl("https://www.apache.org/dyn/closer.lua?preferred=true")
+      val filename = s"spark-$version-bin-hadoop2.7.tgz"
+      val url = s"$preferredMirror/spark/spark-$version/$filename"
       logInfo(s"Downloading Spark $version from $url")
-      if (Seq("wget", url, "-q", "-P", path).! == 0) {
+      try {
+        getFileFromUrl(url, path, filename)
         return
+      } catch {
+        case ex: Exception => logWarning(s"Failed to download Spark $version from $url", ex)
       }
-      logWarning(s"Failed to download Spark $version from $url")
     }
     fail(s"Unable to download Spark $version")
   }
@@ -85,6 +93,34 @@ class HiveExternalCatalogVersionsSuite extends SparkSubmitTestUtils {
     new File(tmpDataDir, name).getCanonicalPath
   }
 
+  private def getFileFromUrl(urlString: String, targetDir: String, filename: String): Unit = {
+    val conf = new SparkConf
+    // if the caller passes the name of an existing file, we want doFetchFile to write over it with
+    // the contents from the specified url.
+    conf.set("spark.files.overwrite", "true")
+    val securityManager = new SecurityManager(conf)
+    val hadoopConf = new Configuration
+
+    val outDir = new File(targetDir)
+    if (!outDir.exists()) {
+      outDir.mkdirs()
+    }
+
+    // propagate exceptions up to the caller of getFileFromUrl
+    Utils.doFetchFile(urlString, outDir, filename, conf, securityManager, hadoopConf)
+  }
+
+  private def getStringFromUrl(urlString: String): String = {
+    val contentFile = File.createTempFile("string-", ".txt")
+    contentFile.deleteOnExit()
+
+    // exceptions will propagate to the caller of getStringFromUrl
+    getFileFromUrl(urlString, contentFile.getParent, contentFile.getName)
+
+    val contentPath = Paths.get(contentFile.toURI)
+    new String(Files.readAllBytes(contentPath), StandardCharsets.UTF_8)
+  }
+
   override def beforeAll(): Unit = {
     super.beforeAll()