Testing your custom Nifi processor

After you create a custom NiFi processor, you can verify that it works using a simple set of steps.

Procedure

Create a class under src/test/java and declare a field with data type org.apache.nifi.util.TestRunner.
```
public class MyProcessorTest {

    private TestRunner testRunner;
    
```
Create a method init() annotated with JUnit’s @Before annotation and initialize the TestRunner.
```
    @Before
    public void init() {
        testRunner = TestRunners.newTestRunner(MyProcessor.class);
    }
```

Create another method and annotate it with JUnit’s @Test. Also, get a JSON payload which will represent the input to the processor.

    @Test
    public void testResponse() throws Exception {
        final Path JSON_SNIPPET = Paths.get("src/test/resources/common/MyProcessor/scroll_input.json");
        final Path JSON_SNIPPET1 = Paths.get("src/test/resources/common/MyProcessor/scroll_input_zero_doc.json");

In the same method, set all the required attributes in the test runner as follows:

         testRunner.setProperty(MyProcessor.SCROLL_DURATION, "1m");
         Map<String, String> attributes = new HashMap<String, String>();
         attributes.put(PARAM_DOT_STOREID, "1");
         attributes.put(CONNECTOR_DOT_NAME, "auth.reindex");
         attributes.put(ENVIRONMENT_DOT_NAME, "auth");
         testRunner.enqueue(JSON_SNIPPET, attributes);
         testRunner.run();
         attributes.put("index.scroll.uri", "_search/scroll");
         testRunner.enqueue(JSON_SNIPPET1, attributes);
         testRunner.run();

In the same method, also set the expected number of FlowFiles transferred to the respective relationships as follows:

        Relationship expectedRel = MyProcessor.RELATIONSHIP_SUCCESS; 
        testRunner.assertTransferCount(expectedRel, 1);
        expectedRel = MyProcessor.RELATIONSHIP_FAILURE; 
        testRunner.assertTransferCount(expectedRel, 0);

Run this class as a JUnit Test. The result of the execution appears under the JUnit View.