Revert "[SPARK-22308] Support alternative unit testing styles in exte…

…rnal applications"

This reverts commit 592cfea.

core/src/test/scala/org/apache/spark/SharedSparkContext.scala

@@ -29,23 +29,10 @@ trait SharedSparkContext extends BeforeAndAfterAll with BeforeAndAfterEach { sel
 
   var conf = new SparkConf(false)
 
-  /**
-   * Initialize the [[SparkContext]].  Generally, this is just called from beforeAll; however, in
-   * test using styles other than FunSuite, there is often code that relies on the session between
-   * test group constructs and the actual tests, which may need this session.  It is purely a
-   * semantic difference, but semantically, it makes more sense to call 'initializeContext' between
-   * a 'describe' and an 'it' call than it does to call 'beforeAll'.
-   */
-  protected def initializeContext(): Unit = {
-    if (null == _sc) {
-      _sc = new SparkContext(
-        "local[4]", "test", conf.set("spark.hadoop.fs.file.impl", classOf[DebugFilesystem].getName))
-    }
-  }
-
   override def beforeAll() {
     super.beforeAll()
-    initializeContext()
+    _sc = new SparkContext(
+      "local[4]", "test", conf.set("spark.hadoop.fs.file.impl", classOf[DebugFilesystem].getName))
   }
 
   override def afterAll() {

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/plans/PlanTest.scala

@@ -17,8 +17,6 @@
 
 package org.apache.spark.sql.catalyst.plans
 
-import org.scalatest.Suite
-
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.analysis.SimpleAnalyzer
@@ -31,13 +29,7 @@ import org.apache.spark.sql.internal.SQLConf
 /**
  * Provides helper methods for comparing plans.
  */
-trait PlanTest extends SparkFunSuite with PlanTestBase
-
-/**
- * Provides helper methods for comparing plans, but without the overhead of
- * mandating a FunSuite.
- */
-trait PlanTestBase extends PredicateHelper { self: Suite =>
+trait PlanTest extends SparkFunSuite with PredicateHelper {
 
   // TODO(gatorsmile): remove this from PlanTest and all the analyzer rules
   protected def conf = SQLConf.get