Add sample app for https://stackoverflow.com/questions/60269753

so60269753/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example</groupId>
+	<artifactId>demo</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>demo</name>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<java.version>1.8</java.version>
+		<spring-batch-core.version>4.2.1.RELEASE</spring-batch-core.version>
+		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
+		<junit.version>4.13</junit.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.batch</groupId>
+			<artifactId>spring-batch-core</artifactId>
+			<version>${spring-batch-core.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.batch</groupId>
+			<artifactId>spring-batch-test</artifactId>
+			<version>${spring-batch-core.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+		    <groupId>junit</groupId>
+		    <artifactId>junit</artifactId>
+			<version>${junit.version}</version>
+		    <scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>${maven-compiler-plugin.version}</version>
+				<configuration>
+					<source>${java.version}</source>
+					<target>${java.version}</target>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

so60269753/src/test/java/com/example/demo/TestExampleWithStepScopeTestExecutionListener.java

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+package com.example.demo;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.batch.core.StepExecution;
+import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
+import org.springframework.batch.core.configuration.annotation.StepScope;
+import org.springframework.batch.item.ExecutionContext;
+import org.springframework.batch.item.file.FlatFileItemReader;
+import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
+import org.springframework.batch.item.file.mapping.PassThroughLineMapper;
+import org.springframework.batch.test.MetaDataInstanceFactory;
+import org.springframework.batch.test.StepScopeTestExecutionListener;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.TestExecutionListeners;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.context.support.DependencyInjectionTestExecutionListener;
+
+@RunWith(SpringRunner.class)
+@TestExecutionListeners({DependencyInjectionTestExecutionListener.class, StepScopeTestExecutionListener.class})
+@ContextConfiguration(classes = TestExampleWithStepScopeTestExecutionListener.MyConfiguration.class)
+public class TestExampleWithStepScopeTestExecutionListener {
+
+	@Autowired
+	private FlatFileItemReader<String> reader;
+
+	public StepExecution getStepExecution() {
+		StepExecution execution = MetaDataInstanceFactory.createStepExecution();
+		execution.getExecutionContext().putString("fileName", "data/input.txt");
+		return execution;
+	}
+
+	@Test
+	public void givenMockedStep_whenReaderCalled_thenSuccess() throws Exception {
+		reader.open(new ExecutionContext());
+		String item = reader.read();
+		Assert.assertEquals("foo", item);
+		item = reader.read();
+		Assert.assertEquals("bar", item);
+		item = reader.read();
+		Assert.assertNull(item);
+		reader.close();
+	}
+
+	@Configuration
+	@EnableBatchProcessing
+	static class MyConfiguration {
+
+		@Bean
+		@StepScope
+		public FlatFileItemReader<String> myFlatFileItemReader(@Value("#{stepExecutionContext['fileName']}") String filename) {
+			return new FlatFileItemReaderBuilder<String>()
+					.name("myFlatFileItemReader")
+					.resource(new ClassPathResource(filename))
+					.lineMapper(new PassThroughLineMapper())
+					.build();
+		}
+	}
+
+}

so60269753/src/test/java/com/example/demo/TestExampleWithStepScopeTestUtils.java

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+package com.example.demo;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.batch.core.StepExecution;
+import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
+import org.springframework.batch.core.configuration.annotation.StepScope;
+import org.springframework.batch.item.ExecutionContext;
+import org.springframework.batch.item.file.FlatFileItemReader;
+import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
+import org.springframework.batch.item.file.mapping.PassThroughLineMapper;
+import org.springframework.batch.test.MetaDataInstanceFactory;
+import org.springframework.batch.test.StepScopeTestUtils;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@ContextConfiguration(classes = TestExampleWithStepScopeTestUtils.MyConfiguration.class)
+public class TestExampleWithStepScopeTestUtils {
+
+	@Autowired
+	private FlatFileItemReader<String> reader;
+
+	@Test
+	public void givenMockedStep_whenReaderCalled_thenSuccess() throws Exception {
+		// given
+		final ExecutionContext ctx = new ExecutionContext();
+		ctx.put("fileName", "data/input.txt");
+		StepExecution stepExecution = MetaDataInstanceFactory.createStepExecution(ctx);
+
+		// when
+		List<String> items = StepScopeTestUtils.doInStepScope(stepExecution, () -> {
+			List<String> result = new ArrayList<>();
+			String item;
+			reader.open(new ExecutionContext());
+			while ((item = reader.read()) != null) {
+				result.add(item);
+			}
+			reader.close();
+			return result;
+		});
+
+		// then
+		Assert.assertEquals(2, items.size());
+		Assert.assertEquals("foo", items.get(0));
+		Assert.assertEquals("bar", items.get(1));
+	}
+
+	@Configuration
+	@EnableBatchProcessing
+	static class MyConfiguration {
+
+		@Bean
+		@StepScope
+		public FlatFileItemReader<String> myFlatFileItemReader(@Value("#{stepExecutionContext['fileName']}") String filename) {
+			return new FlatFileItemReaderBuilder<String>()
+					.name("myFlatFileItemReader")
+					.resource(new ClassPathResource(filename))
+					.lineMapper(new PassThroughLineMapper())
+					.build();
+		}
+	}
+
+}

so60269753/src/test/resources/data/input.txt

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+foo
+bar