How to stop a running SparkContext before opening the new one - scala

Question

I am executing tests in Scala with Spark creating a SparkContext as follows:
val conf = new SparkConf().setMaster("local").setAppName("test")
val sc = new SparkContext(conf)
After the first execution there was no error. But now I am getting this message (and a failed test notification):
Only one SparkContext may be running in this JVM (see SPARK-2243).
It looks like I need to check if there is any running SparkContext and stop it before launching a new one (I do not want to allow multiple contexts).
How can I do this?
UPDATE:
I tried this, but there is the same error (I am running tests from IntellijIdea and I make the code before executing it):
val conf = new SparkConf().setMaster("local").setAppName("test")
// also tried: .set("spark.driver.allowMultipleContexts", "true")
UPDATE 2:
class TestApp extends SparkFunSuite with TestSuiteBase {
// use longer wait time to ensure job completion
override def maxWaitTimeMillis: Int = 20000
System.clearProperty("spark.driver.port")
System.clearProperty("spark.hostPort")
var ssc: StreamingContext = _
val config: SparkConf = new SparkConf().setMaster("local").setAppName("test")
.set("spark.driver.allowMultipleContexts", "true")
val sc: SparkContext = new SparkContext(config)
//...
test("Test1")
{
sc.stop()
}
}

Answer 1

To stop existing context you can use stop method on a given SparkContext instance.
import org.apache.spark.{SparkContext, SparkConf}
val conf: SparkConf = ???
val sc: SparkContext = new SparkContext(conf)
...
sc.stop()
To reuse existing context or create a new one you can use SparkContex.getOrCreate method.
val sc1 = SparkContext.getOrCreate(conf)
...
val sc2 = SparkContext.getOrCreate(conf)
When used in test suites both methods can be used to achieve different things:
stop - stopping context in afterAll method (see for example MLlibTestSparkContext.afterAll)
getOrCreate - to get active instance in individual test cases (see for example QuantileDiscretizerSuite)