TeamCity Cloud 2024.07 Help


EMMA Integration Notes

The following steps are performed when collecting coverage with EMMA:

1. After each compilation step (with javac/javac2), the build agent invokes EMMA to instrument the compiled classes and to store the location of the source files. As a result, the coverage.em file containing the classes metadata is created in the build checkout directory. The collected source paths of the Java files are used to generate the final HTML report.

2. Test run. At this stage, the actual runtime coverage information is collected. This process results in creation of the file. If there are several test tasks, data is appended to

3. Report generation. When the build ends, TeamCity generates an HTML coverage report, creates the file with the report and uploads it to the server. It also generates and uploads the summary report in the coverage.txt file, and the original coverage.e(c|m) files to allow viewing coverage from the TeamCity plugin for IntelliJ IDEA.

Configuring Coverage with EMMA

To configure code coverage by means of EMMA engine, follow these steps:

  1. While creating/editing Build Configuration, go to the Build Step page.

  2. Select the Ant build runner.

  3. In the Code Coverage section, choose EMMA as a coverage tool in the drop-down menu.

  4. Set up the coverage options — refer to the description of the available options below.



Include Source Files in the Coverage Data

Check this option to include source files into the code coverage report (you'll be able to see sources on the Web).

Coverage Instrumentation Parameters

Use this field to specify the filters to be used for creating the code coverage report. These filters define classes to be exempted from instrumentation. For detailed description of filters, refer to EMMA documentation.


No coverage, there is a message: EMMA: no output created: metadata is empty

Please make sure that all your classes (whose coverage is to be evaluated) are recompiled during the build. Usually this requires adding a "clean" task at the beginning of the build.

java.lang.NoClassDefFoundError: com/vladium/emma/rt/RT

This message appears when your build loads EMMA-instrumented class files in runtime, and it cannot find emma.jar file in classpath. For test tasks, like junit or testng, TeamCity adds emma.jar to classpath automatically. But, for other tasks, this is not the case, and you might need to modify your build script or to exclude some classes from instrumentation.

If your build runs a java task which uses your own compiled classes, you'll have to either add emma.jar to the classpath of the java task, or to ensure that classes used in your java task are not instrumented. Besides, you should run your java task with the fork=true attribute.

The corresponding emma.jar file can be taken from buildAgent/plugins/coveragePlugin/lib/emma.jar. For a typical build, the corresponding include path would be ../../plugins/coveragePlugin/lib/emma.jar.

To exclude classes from compilation, use settings for EMMA instrumentation task. TeamCity UI has a field to pass these parameters to EMMA, labeled "Coverage instrumentation parameters". To exclude some package from instrumenting, use the following syntax: -ix*,*,-*Test*, where the package* contains files for your custom task.

EMMA coverage results are unstable

Please make sure that your junit task has the fork=true attribute. The recommended combination of attributes is fork=true forkmode=once.

Last modified: 12 January 2022