[SPARK-22940][SQL] HiveExternalCatalogVersionsSuite should succeed on platforms that don't have wget

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()