JaCoCo with Maven - missing execution data file

You should not invoke the agent after the install phase but before, so instead of invoking:

mvn clean install jacoco:prepare-agent jacoco:report

You should invoke

mvn clean jacoco:prepare-agent install jacoco:report

The main reason is: the agent will not participate to the build lifecycle, the test phase will already be executed as part of the install phase, then Maven will execute the agent as per command line invocation, but it will be too late.

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You should probably also change the plugin configuration above to:

<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.7.6.201602180812</version>
    <executions>
        <execution>
            <id>jacoco-initialize</id>
            <goals>
                <goal>prepare-agent</goal>
            </goals>
        </execution>
        <execution>
            <id>jacoco-site</id>
            <phase>package</phase>
            <goals>
                <goal>report</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Note: I removed the configuration section, because it was actually pointing to default values. Moreover, XML elements are case sensitives here, so your datafile element was simply ignored, it should have been dataFile instead. The same applies to destFile.

The prepare-agent goal is already using ${project.build.directory}/jacoco.exec as default destFile value, the same applied to the dataFile value for the report goal. The main reason for this change would be a more flexible and standard build, not relying on artifactId as project name (the default, but still not mandatory) and using the more generic ${project.build.directory} property instead to point directly at target.

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Final note: make sure to configure the Jacoco Plugin executions within the build/plugins section and not build/pluginManagement/plugins section. The pluginManagement section is meant for governance and common harmonization of versions or configurations, but it will be ignored if the corresponding plugin would not be declared under build/plugins.
As per official Maven POM reference

pluginManagement: is an element that is seen along side plugins. Plugin Management contains plugin elements in much the same way, except that rather than configuring plugin information for this particular project build, it is intended to configure project builds that inherit from this one. However, this only configures plugins that are actually referenced within the plugins element in the children. The children have every right to override pluginManagement definitions.

(note: bold is mine)

• JaCoCo reports get created from the execution data file.
  
• If this file is not present then JaCoCo report goal skips the report creation.
  
• So it is compulsory to create the execution data file.
  

Reasons due to which execution data file will not get created are the following
- Tests are not present.
- All tests are ignored.
- Surefire plugin is missing.
- JaCoCo's prepare-agent goal is not executed, which sets argLine which is needed to configure to surefire.
- Surefire plugin is not configured with JaCoCo's agent.

I think that "destfile" and "datafile" are case sensitive so try to replace them with "destFile" and "dataFile", maybe it'll work :)