How to unit test Spring Integration’s int-file:inbound-channel-adapter - unit-testing

Question

I have a simple Spring Integration flow where I read XML files from a given directory, and send their content to another channel and do other processing.
After the processing is done, I need to move the input file in an archive/error directory.
file-integration.xml:
<?xml version="1.0" encoding="utf-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:int-file="http://www.springframework.org/schema/integration/file"
xmlns:int="http://www.springframework.org/schema/integration"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/integration/file https://www.springframework.org/schema/integration/file/spring-integration-file.xsd
http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<import resource="transaction-manager-configuration.xml"/>
<context:property-placeholder location="classpath:app.properties"/>
<int:channel id="inputFileChannel"/>
<int-file:inbound-channel-adapter channel="inputFileChannel"
directory="${inputDir}"
filename-pattern="*.xml">
<int:poller fixed-delay="1000">
<int:transactional transaction-manager="txManager" synchronization-factory="syncFactory"/>
</int:poller>
</int-file:inbound-channel-adapter>
<int-file:file-to-string-transformer input-channel="inputFileChannel"
output-channel="contentChannel"/>
<int:channel id="contentChannel"/>
<int:channel id="inputFileSuccessChannel"/>
<int:channel id="inputFileErrorChannel"/>
<!-- Move file after being processed -->
<int:transaction-synchronization-factory id="syncFactory">
<int:after-commit channel="inputFileSuccessChannel"/>
<int:after-rollback channel="inputFileErrorChannel"/>
</int:transaction-synchronization-factory>
<int-file:outbound-channel-adapter channel="inputFileSuccessChannel"
directory="${archiveDir}"
delete-source-files="true"/>
<int-file:outbound-channel-adapter channel="inputFileErrorChannel"
directory="${errorDir}"
delete-source-files="true"/>
</beans>
My questions:
In a unit test context, how can I create & push an in-memory file in inputFileChannel, without relying on the real filesystem?
How can I test that my input file has been pushed to inputFileSuccessChannel / inputFileErrorChannel? How to mock the <int-file:outbound-channel-adapter/>?
Again in my unit test context without relying on the real filesystem, how can I test that my in-memory input file has been deleted (as configured with the delete-source-files="true" statements)?
At the moment, I have a JUnit 5 test class FileIntegrationTest.java:
#ExtendWith(SpringExtension.class)
#ContextConfiguration
#PropertySource("classpath:app.properties")
#SpringIntegrationTest
public class FileIntegrationTest {
#Autowired
MessageChannel inputFileChannel;
#Autowired
QueueChannel contentTestChannel;
#Test
void shouldReadInputFile_thenMoveIt() {
// arrange
File inputFile = new … // question 1
Message<File> inputMessage = MessageBuilder.withPayload(file).build();
// act
inputFileChannel.send(inputMessage);
// assert
assertThat(contentTestChannel.getQueueSize(), is(1));
assertThat(inputFileSuccessChannel contains my input file); // question 2
assertThat(inputFile has been deleted); // question 3
}
}
And its context file FileIntegrationTest-context.xml:
<?xml version="1.0" encoding="utf-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:int="http://www.springframework.org/schema/integration"
xsi:schemaLocation="
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/integration https://www.springframework.org/schema/integration/spring-integration.xsd">
<import resource="classpath:/META-INF/spring/integration/file-integration.xml"/>
<int:bridge input-channel="contentChannel"
output-channel="contentTestChannel"/>
<int:channel id="contentTestChannel">
<int:queue/>
</int:channel>
</beans>
The official Spring Testing support page mentions the use of mocks, but I’m confused how to use it. I’ve checked out https://github.com/spring-projects/spring-integration-samples as well, but I could find a proper solution.

Answer 1

Yes
Add a channel interceptor to the channel, or see the documentation about mocking endpoints.
If you send a test file to the channel; you can check to see if still exists when the test completes.