SparkTest.NET 1.2.1

SparkTest.NET

• Getting Started
• Documentation

Support for testing Spark dotnet applications

Features

• Test framework agnostic
• Zero dependencies (except spark dotnet!)
• Easy to use
• Stable and fast spark debug usage tailored to testing

// import the factory
using static SparkTest.NET.SparkSessionFactory;

...

// Then you can use a spark session within a test
[Fact]
public static void SomeTest()
{
    var result = UseSession(session =>
    {
        // session is safe to use here
        ...
        // return something to assert against
        return ...
    });
    ...
}

Getting Started

To use this library, simply include SparkTest.NET.dll in your project or grab it from NuGet, and add this to the top of each test .cs file that needs it:

using static SparkTest.NET.SparkSessionFactory;

Why?

There is no documented/supported way to write tests for Spark dotnet applications.

There are a number of foot guns and this aims to disarm them.

• spark-debug needs to run from the executing location of the tests assembly, this starts spark-debug in the correct location, and ensures that it is stopped after all the tests are complete
  • If spark-debug is already running, it will not be started, good for CI
• spark-debug without any tuning is not optimized for short running tests, this,
  • Sets the log level to Error (default is super chatty)
  • Disables the Spark UI settings
  • Stops Spark from spreading out and localizes work
  • Disables shuffling for Spark SQL
  • Enables all cores on the spark submit job
• SparkSession is not thread safe, its backed by a single SparkContext, this enforces that all operations that need a SparkSession run sequentially

The following settings configure the spark-submit process,

They can be set via the environment or from the test csproj file,

eg.

<ItemGroup>
    <AssemblyMetadata Include="SparkTest.NET.ExtraJars"
                      Value="azure-storage-3.1.0.jar,spark-xml-assembly-0.14.0.jar"/>
</ItemGroup>

or

export SPARK_DEBUG_EXTRA_JARS=azure-storage-3.1.0.jar,spark-xml-assembly-0.14.0.jar

For more details/information have a look the test projects or create an issue.