Align XML and Java based configuration

This commit aligns the XML and Java based validations.

When using XML to configure a chunk oriented step both an ItemReader and
ItemWriter are requied. However when using Java based configuration the
ItemWriter is optional if an ItemProcessor is present.

Having no ItemWriter and only an ItemProcessor lead to strange results
in one of our batch jobs, which was accidentily configured without an
ItemProcessor.

Related: BATCH-1520
Fixes: BATCH-2624

Author: mminella

spring-batch-core/src/main/java/org/springframework/batch/core/step/builder/FaultTolerantStepBuilder.java

@@ -178,7 +178,7 @@ protected void registerStepListenerAsSkipListener() {
 	@Override
 	protected Tasklet createTasklet() {
 		Assert.state(getReader() != null, "ItemReader must be provided");
-		Assert.state(getProcessor() != null || getWriter() != null, "ItemWriter or ItemProcessor must be provided");
+		Assert.state(getWriter() != null, "ItemWriter must be provided");
 		addSpecialExceptions();
 		registerSkipListeners();
 		ChunkProvider<I> chunkProvider = createChunkProvider();
@@ -773,6 +773,6 @@ public boolean equals(Object obj) {
 			}
 			return chunkListener.equals(obj);
 		}
-		
+
 	}
 }

spring-batch-core/src/main/java/org/springframework/batch/core/step/builder/SimpleStepBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2014 the original author or authors.
+ * Copyright 2006-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -153,7 +153,7 @@ private void checkAndAddItemListener(StepListener stepListener) {
 	@Override
 	protected Tasklet createTasklet() {
 		Assert.state(reader != null, "ItemReader must be provided");
-		Assert.state(processor != null || writer != null, "ItemWriter or ItemProcessor must be provided");
+		Assert.state(writer != null, "ItemWriter must be provided");
 		RepeatOperations repeatOperations = createChunkOperations();
 		SimpleChunkProvider<I> chunkProvider = new SimpleChunkProvider<I>(reader, repeatOperations);
 		SimpleChunkProcessor<I, O> chunkProcessor = new SimpleChunkProcessor<I, O>(processor, writer);

spring-batch-core/src/test/java/org/springframework/batch/core/step/item/FaultTolerantStepFactoryBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2014 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -371,30 +371,6 @@ public void testProcessFilter() throws Exception {
 				.getName()));
 	}
 
-	@Test
-	public void testNullWriter() throws Exception {
-
-		factory.setItemWriter(null);
-		Step step = factory.getObject();
-
-		step.execute(stepExecution);
-
-		assertEquals(0, stepExecution.getSkipCount());
-		assertEquals(0, stepExecution.getReadSkipCount());
-		assertEquals(5, stepExecution.getReadCount());
-		// Write count is incremented even if nothing happens
-		assertEquals(5, stepExecution.getWriteCount());
-		assertEquals(0, stepExecution.getFilterCount());
-		assertEquals(0, stepExecution.getRollbackCount());
-
-		// writer skips "4"
-		assertTrue(reader.getRead().contains("4"));
-
-		assertEquals(BatchStatus.COMPLETED, stepExecution.getStatus());
-		assertStepExecutionsAreEqual(stepExecution, repository.getLastStepExecution(jobExecution.getJobInstance(), step
-				.getName()));
-	}
-
 	/**
 	 * Check items causing errors are skipped as expected.
 	 */

spring-batch-core/src/test/java/org/springframework/batch/core/step/item/SimpleStepFactoryBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2013 the original author or authors.
+ * Copyright 2006-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@
 import java.util.List;
 
 import org.junit.Before;
+import org.junit.Ignore;
 import org.junit.Test;
 import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.ChunkListener;
@@ -475,32 +476,6 @@ public void onWriteError(Exception exception, List<? extends String> items) {
 
 	}
 
-	@Test
-	public void testNullWriter() throws Exception {
-
-		SimpleStepFactoryBean<String, String> factory = getStepFactory(new String[] { "foo", "bar", "spam" });
-		factory.setItemWriter(null);
-		factory.setItemProcessor(new ItemProcessor<String, String>() {
-			@Override
-			public String process(String item) throws Exception {
-				written.add(item);
-				return null;
-			}
-		});
-
-		Step step = factory.getObject();
-
-		job.setSteps(Collections.singletonList(step));
-
-		JobExecution jobExecution = repository.createJobExecution(job.getName(), new JobParameters());
-
-		job.execute(jobExecution);
-
-		assertEquals(BatchStatus.COMPLETED, jobExecution.getStatus());
-		assertEquals("[foo, bar, spam]", written.toString());
-
-	}
-
 	private SimpleStepFactoryBean<String, String> getStepFactory(String... args) throws Exception {
 		SimpleStepFactoryBean<String, String> factory = new SimpleStepFactoryBean<String, String>();