Importing spark.implicits._ in scala

Question

I am trying to import spark.implicits._ Apparently, this is an object inside a class in scala. when i import it in a method like so:

def f() = {
  val spark          


        

Answer 1

Thanks to @bluenote10 for helpful answer and we can simplify it again, for example without helper object testImplicits:

private object testImplicits extends SQLImplicits {
  protected override def _sqlContext: SQLContext = self.spark.sqlContext
}

with following way:

trait SharedSparkSession extends BeforeAndAfterAll { self: Suite =>

  /**
   * The SparkSession instance to use for all tests in one suite.
   */
  private var spark: SparkSession = _

  /**
   * Returns local running SparkSession instance.
   * @return SparkSession instance `spark`
   */
  protected def sparkSession: SparkSession = spark

  /**
   * A helper implicit value that allows us to import SQL implicits.
   */
  protected lazy val sqlImplicits: SQLImplicits = self.sparkSession.implicits

  /**
   * Starts a new local spark session for tests.
   */
  protected def startSparkSession(): Unit = {
    if (spark == null) {
      spark = SparkSession
        .builder()
        .master("local[2]")
        .appName("Testing Spark Session")
        .getOrCreate()
    }
  }

  /**
   * Stops existing local spark session.
   */
  protected def stopSparkSession(): Unit = {
    if (spark != null) {
      spark.stop()
      spark = null
    }
  }

  /**
   * Runs before all tests and starts spark session.
   */
  override def beforeAll(): Unit = {
    startSparkSession()
    super.beforeAll()
  }

  /**
   * Runs after all tests and stops existing spark session.
   */
  override def afterAll(): Unit = {
    super.afterAll()
    stopSparkSession()
  }
}

and finally we can use SharedSparkSession for unit tests and import sqlImplicits:

class SomeSuite extends FunSuite with SharedSparkSession {
  // We can import sql implicits 
  import sqlImplicits._

  // We can use method sparkSession which returns locally running spark session
  test("some test") {
    val df = sparkSession.sparkContext.parallelize(List(1,2,3)).toDF()
    //...
  }
}