Maven resources plugin filtering not working

Question

I have a POM with the following in:

<properties>
    <prop1>xxxxxxxxxx</prop1>
</properties>
<build>
    <finalName>${project.artifactId}-${project.version}</finalName>
    <resources>
        <resource>
            <directory>src/test/resources</directory>
            <filtering>true</filtering>
        </resource>
    </resources>
 </build>

And I have a properties file under src/test/resources:

p1=${prop1}

My goal is to copy the .properties file into target/test-classes directory and automatically change the value of p1. But it does not work. It copies the resource but does not change the value.

Answer 1

The problem is that you're configuring main resources instead of test resources; the main resources are configured with the resource element, whereas the test resources are configured with the testResource element. With the current configuration, the files under src/test/resources would be treated as filtered main resources, and the actual test resources would be unfiltered. This is why the copied properties file under target/test-classes is not filtered.

What you're looking for is:

<testResources>
  <testResource>
    <directory>src/test/resources</directory>
    <filtering>true</filtering>
  </testResource>
</testResources>

With this, the files under src/test/resources will be treated as filtered test resources, and the main resources will be left untouched.

Answer 2

Following is the Note from the official reference document: (refer to https://docs.spring.io/spring-boot/docs/2.3.2.RELEASE/maven-plugin/reference/html/)

Note that, since the application.properties and application.yml files accept Spring style placeholders (${…​}), the Maven filtering is changed to use @..@ placeholders. (You can override that by setting a Maven property called resource.delimiter.)