Practical example for setting custom options as beamTestPipelineOptions for TestPipeline in apache beam

DagOptions.java

public interface DagOptions extends PipelineOptions {
    @Description("Dag options")
    @Default.String("HELLOWORLD")
    String getDagType();
    void setDagType(String dagType);
}

Test.java

package org.example.dags;

import org.apache.beam.sdk.testing.NeedsRunner;
import org.apache.beam.sdk.testing.TestPipeline;
import org.apache.beam.sdk.testing.TestPipelineOptions;
import org.example.App;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.experimental.categories.Category;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import static org.example.Utils.asJsonStr;
import static org.junit.Assert.assertTrue;

public class HelloWorldDagTest {
    public interface TestHWOptions extends TestPipelineOptions, App.DagOptions {}

    private List<String> input;
    private String dagType;

    @Rule
    public final transient TestPipeline p = TestPipeline.create();

    @Before
    public void setUp() {
        // Test pipeline options as JSON array.
        // I have used Jackson to safely convert Java object into JSON string
        // https://beam.apache.org/releases/javadoc/2.57.0/org/apache/beam/sdk/testing/TestPipeline.html
        // https://www.json.org/json-en.html
        String[] pOpts = new String[]{
                "--runner=DirectRunner"
        };
        System.setProperty("beamTestPipelineOptions", asJsonStr(pOpts));
        input = new ArrayList<String>(Arrays.asList("Hello", "World."));
        dagType = "HELLOWORLD";
    }

    @Test
    @Category(NeedsRunner.class)
    public void testProcess() {
        p
                .getOptions()
                .as(App.DagOptions.class)
                .setDagType(dagType);
        p.run();
        assertTrue(true);
    }
}

Utils.java

package org.example;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.ArrayList;

public class Utils {

    /***
     * Takes String array and convert into JSON string
     * @param arr as String array
     * @return Json string
     */
    public static String asJsonStr(String[] arr) {
        ObjectMapper objectMapper = new ObjectMapper();

        try {
            return objectMapper.writeValueAsString(arr);
        } catch (JsonProcessingException e) {
            throw new RuntimeException(e);
        }
    }
}