JaCoCo - Ant Tasks

# Ant Tasks

JaCoCo comes with Ant tasks to launch Java programs with execution recording and for creating coverage reports from the recorded data. Execution data can be collected and managed with the tasks `coverage`, `agent`, `dump` and `merge`. Reports in different formats are creates with the `report` task. For offline instrumentation the task `instrument` can be used to prepare class files.

If you want to have line number information included in the coverage reports or you want source code highlighting the class files of the test target must be compiled with debug information.

## Example

The JaCoCo distribution contains a simple example how code coverage can be added to a Ant based build. The build script compiles Java sources, runs an simple Java programm and creates a coverage report. The complete example is located in the `./doc/examples/build` folder of the distribution.

## Prerequisites

The JaCoCo Ant tasks require

- Ant 1.7.0 or higher and
- Java 1.5 or higher (for both, the Ant runner and the test executor).

All tasks are defined in `jacocoant.jar` (which is part of the distribution) and can be included in your Ant scripts with the usual `taskdef` declaration:

    <project name="Example" xmlns:jacoco="antlib:org.jacoco.ant">

        <taskdef uri="antlib:org.jacoco.ant" resource="org/jacoco/ant/antlib.xml">
            <classpath path="path_to_jacoco/lib/jacocoant.jar"/>
        </taskdef>

        ...

    </project>

Alternatively you might also place the `jacocoant.jar` in your Ant `ANT_HOME/lib` folder. If you use the name space URI `antlib:org.jacoco.ant` for JaCoCo tasks Ant will find them automatically without the `taskdef` declaration above.

Declaring a XML namespace for JaCoCo tasks is optional but always recommended if you mix tasks from different libraries. All subsequent examples use the `jacoco` prefix declared above. If you don't declare a separate namespace the `jacoco` prefix must be removed from the following examples.

## Task `coverage`

The standard Ant tasks to launch Java programs are `java`, `junit` and `testng`. To add code coverage recording to these tasks they can simply be wrapped with the `coverage` task as shown in the following examples:

    <jacoco:coverage>
        <java classname="org.jacoco.examples.HelloJaCoCo" fork="true">
            <classpath>
                <pathelement location="./bin"/>
            </classpath>
        </java>
    </jacoco:coverage>

    <jacoco:coverage>
        <junit fork="true" forkmode="once">
            <test name="org.jacoco.examples.HelloJaCoCoTest"/>
            <classpath>
                <pathelement location="./bin"/>
            </classpath>
        </junit>
    </jacoco:coverage>

Resulting coverage information is collected during execution and written to a file when the process terminates. Note the `fork` attribute above in the wrapped `java` task.

The nested task always has to declare `fork="true"`, otherwise the `coverage` task can't record coverage information and will fail. In addition the `junit` task should declare `forkmode="once"` to avoid starting a new JVM for every single test case and decreasing execution performance dramatically (unless this is required by the nature of the test cases). Note that `forkmode="perTest"` or `forkmode="perBatch"` should not be combined with `append="false"` as the execution data file is overwritten with the execution of every test.

The coverage task must wrap exactly one task. While it typically works without any configuration, the behavior can be adjusted with some optional attributes:

Attribute | Description | Default
`enabled` | If set to `true` coverage data will be collected for the contained task. | `true`
`destfile` | Path to the output file for execution data. | `jacoco.exec`
`append` | If set to `true` and the execution data file already exists, coverage data is appended to the existing file. If set to `false`, an existing execution data file will be replaced. | `true`
`includes` | A list of class names that should be included in execution analysis. The list entries are separated by a colon (`:`) and may use wildcard characters (`*` and `?`). Except for performance optimization or technical corner cases this option is normally not required. | `*` (all classes)
`excludes` | A list of class names that should be excluded from execution analysis. The list entries are separated by a colon (`:`) and may use wildcard characters (`*` and `?`). Except for performance optimization or technical corner cases this option is normally not required. | empty (no excluded classes)
`exclclassloader` | A list of class loader names, that should be excluded from execution analysis. The list entries are separated by a colon (`:`) and may use wildcard characters (`*` and `?`). This option might be required in case of special frameworks that conflict with JaCoCo code instrumentation, in particular class loaders that do not have access to the Java runtime classes. | `sun.reflect.DelegatingClassLoader`
`inclbootstrapclasses` | Specifies whether also classes from the bootstrap classloader should be instrumented. Use this feature with caution, it needs heavy includes/excludes tuning. | `false`
`inclnolocationclasses` | Specifies whether also classes without a source location should be instrumented. Normally such classes are generated at runtime e.g. by mocking frameworks and are therefore excluded by default. | `false`
`sessionid` | A session identifier that is written with the execution data. Without this parameter a random identifier is created by the agent. | auto-generated
`dumponexit` | If set to `true` coverage data will be written on VM shutdown. | `true`
`output` | Output method to use for writing coverage data. Valid options are: `file`: At VM termination execution data is written to the file specified in the `destfile` attribute. `tcpserver`: The agent listens for incoming connections on the TCP port specified by the `address` and `port` attribute. Execution data is written to this TCP connection. `tcpclient`: At startup the agent connects to the TCP port specified by the `address` and `port` attribute. Execution data is written to this TCP connection. `none`: Do not produce any output. | `file`
`address` | IP address or hostname to bind to when the output method is `tcpserver` or connect to when the output method is `tcpclient`. In `tcpserver` mode the value "`*`" causes the agent to accept connections on any local address. | loopback interface
`port` | Port to bind to when the output method is `tcpserver` or connect to when the output method is `tcpclient`. In `tcpserver` mode the port must be available, which means that if multiple JaCoCo agents should run on the same machine, different ports have to be specified. | `6300`
`classdumpdir` | Location relative to the working directory where all class files seen by the agent are dumped to. This can be useful for debugging purposes or in case of dynamically created classes for example when scripting engines are used. | no dumps
`jmx` | If set to `true` the agent exposes functionality via JMX under the name `org.jacoco:type=Runtime`. | `false`

## Task `agent`

If the `coverage` task is not suitable for your launch target, you might alternatively use the `agent` task to create the Java agent parameter. The following example defines a Ant property with the name `agentvmparam` that can be directly used as a Java VM parameter:

    <jacoco:agent property="agentvmparam"/>

This task has the same attributes as the `coverage` task plus an additional property to specify the target property name:

Attribute | Description | Default
`enabled` | When this variable is set to `false` the value of `property` will be set to an empty string, effectively disabling coverage instrumentation for any tasks that used the value. | `true`
`property` | Name of the Ant property to set. | none (required)
All attributes of the `coverage` task.

## Task `dump`

This task allows to remotely collect execution data from another JVM without stopping it. For example:

    <jacoco:dump address="server.example.com" reset="true" destfile="remote.exec"/>

Remote dumps are usefull for long running Java processes like application servers.

The target JVM needs to have a JaCoCo agent configured with `output` mode `tcpserver`. See `coverage` and `agent` tasks above.

The `dump` task has the following attributes:

Attribute | Description | Default
`address` | Target IP address or DNS name. | `localhost`
`port` | Target TCP port. | `6300`
`retryCount` | Number of retries which the goal will attempt to establish a connection. This can be used to wait until the target JVM is successfully launched. | `10`
`dump` | Flag whether execution data should be dumped. | `true`
`reset` | Flag whether execution data should be reset in the target agent after the dump. | `false`
`destfile` | File location to write the collected execution data to. | none (required if dump=true)
`append` | If set to `true` and the execution data file already exists, coverage data is appended to the existing file. If set to `false`, an existing execution data file will be replaced. | `true`

## Task `merge`

This task can be used to merge the execution data from multiple test runs into a single data store.

    <jacoco:merge destfile="merged.exec">
        <fileset dir="executionData" includes="*.exec"/>
    </jacoco:merge>

The task definition can contain any number of resource collection types and has the following mandatory attribute:

Attribute | Description | Default
`destfile` | File location to write the merged execution data to. | none (required)

## Task `report`

Finally different reports can be created with the `report` task. A report task declaration consists of different sections, two specify the input data, additional ones specify the output formats:

    <jacoco:report>

        <executiondata>
            <file file="jacoco.exec"/>
        </executiondata>

        <structure name="Example Project">
            <classfiles>
                <fileset dir="classes"/>
            </classfiles>
            <sourcefiles encoding="UTF-8">
                <fileset dir="src"/>
            </sourcefiles>
        </structure>

        <html destdir="report"/>

    </jacoco:report>

As you can see from the example above the `report` task is based on several nested elements:

### Element `executiondata`

Within this element Ant resources and resource collections can be specified, that represent JaCoCo execution data files. If more than one execution data file is specified, execution data is combined. A particular piece of code is considered executed when it is marked as such in any of the input files.

### Element `structure`

This element defines the report structure. It might contain the following nested elements:

- `classfiles`: Container element for Ant resources and resource collections that can specify Java class files, archive files (jar, war, ear etc. or Pack200) or folders containing class files. Archives and folders are searched recursively for class files.
- `sourcefiles`: Optional container element for Ant resources and resource collections that specify corresponding source files. If source files are specified, some report formats include highlighted source code. Source files can be specified as individual files or as source directories.

The `sourcefiles` element has these optional attributes:

Attribute | Description | Default
`encoding` | Character encoding of the source files. | Platform default encoding
`tabwidth` | Number of whitespace characters that represent a tab character. | 4 characters

Important: Source file resources must always be specified relative to the respective source folder. If directory resources are given, they must directly point to source folders. Otherwise source lookup will not succeed.

Note that the `classfiles` and `sourcefiles` elements accept any Ant resource collection. Therefore also filtering the class file set is possible and allows to narrow the scope of the report, for example:

    <classfiles>
        <fileset dir="classes">
            <include name="org/jacoco/examples/important/**/*.class"/>
        </fileset>
    </classfiles>

Performance Warning: Although it is technically possible and sometimes convenient to use Ant's `zipfileset` to specify class or source files, this resource type has poor performance characteristics and comes with an huge memory overhead especially for large scale projects.

The structure can be refined with a hierarchy of `group` elements. This way the coverage report can reflect different modules of a software project. For each group element the corresponding class and source files can be specified separately. For example:

    <structure name="Example Project">
        <group name="Server">
            <classfiles>
                <fileset dir="${workspace.dir}/org.jacoco.example.server/classes"/>
            </classfiles>
            <sourcefiles>
                <fileset dir="${workspace.dir}/org.jacoco.example.server/src"/>
            </sourcefiles>
        </group>
        <group name="Client">
            <classfiles>
                <fileset dir="${workspace.dir}/org.jacoco.example.client/classes"/>
            </classfiles>
            <sourcefiles>
                <fileset dir="${workspace.dir}/org.jacoco.example.client/src"/>
            </sourcefiles>
        </group>

        ...

    </structure>

Both `structure` and `group` elements have the following mandatory attribute:

Attribute | Description | Default
`name` | Name of the structure or group. | none (required)

### Element `html`

Create a multi-page report in HTML format. The report can either be written as multiple files into a directory or compressed into a single ZIP file.

Attribute | Description | Default
`destdir` | Directory to create the report in. Either this property or `destfile` has to be supplied. | none (required)
`destfile` | Zip file to create the report in. Either this property or `destdir` has to be supplied. | none (required)
`footer` | Footer text for each report page. | no footer
`encoding` | Character encoding of generated HTML pages. | `UTF-8`
`locale` | Locale specified as ISO code (en, fr, jp, ...) used for number formating. Locale country and variant can be separated with an underscore (de_CH). | platform locale

### Element `xml`

Create a single-file report in XML format.

Attribute | Description | Default
`destfile` | Location to write the report file to. | none (required)
`encoding` | Encoding of the generated XML document. | `UTF-8`

### Element `csv`

Create single-file report in CSV format.

Attribute | Description | Default
`destfile` | Location to write the report file to. | none (required)
`encoding` | Encoding of the generated CSV document. | `UTF-8`

### Element `check`

This report type does not actually create a report. It checks coverage counters and reports violations of configured rules. Every rule is applied to elements of a given type (class, package, bundle, etc.) and has a list of limits which are checked for every element. The following example checks that for every package the line coverage is at least 80% and no class is missed:

    <check>
        <rule element="PACKAGE">
            <limit counter="LINE" value="COVEREDRATIO" minimum="0.80"/>
            <limit counter="CLASS" value="MISSEDCOUNT" maximum="0"/>
        </rule>
    </check>

The `check` element has the following attributes:

Attribute | Description | Default
`rules` | List of rules to check. | none
`failonviolation` | Specifies whether build should fail in case of rule violations. | `true`
`violationsproperty` | The name of an Ant property which is filled with the violation messages. | none

Within the `check` element any number of `rule` elements can be nested:

Attribute | Description | Default
`element` | The elements this rule applies to. Possible values are `BUNLDE`, `PACKAGE`, `CLASS`, `SOURCEFILE` and `METHOD`. | `BUNLDE`
`includes` | A list of element names that should be checked. The list entries are separated by a colon (:) and may use wildcard characters (* and ?). | `*`
`excludes` | A list of element names that should not be checked. The list entries are separated by a colon (:) and may use wildcard characters (* and ?). | empty (no excludes)
`limits` | List of limits to check. | none

Within the `rule` element any number of `limit` elements can be nested:

Attribute | Description | Default
`counter` | The counter which should be checked. Possible options are `INSTRUCTION`, `LINE`, `BRANCH`, `COMPLEXITY`, `METHOD` and `CLASS`. | `INSTRUCTION`
`value` | The counter value that should be checked. Possible options are `TOTALCOUNT`, `MISSEDCOUNT`, `COVEREDCOUNT`, `MISSEDRATIO` and `COVEREDRATIO`. | `COVEREDRATIO`
`minimum` | Expected minmimum value. If the minimum refers to a ratio the range is from 0.0 to 1.0 where the number of decimal places will also determine the precision in error messages. | none
`maximum` | Expected maximum value. | none

## Task `instrument`

Warning: The preferred way for code coverage analysis with JaCoCo is on-the-fly instrumentation. Offline instrumentation has several drawbacks and should only be used if a specific scenario explicitly requires this mode. Please consult documentation about offline instrumentation before using this mode.

This task is used for offline instrumentation of class files. The task takes a set of files and writes instrumented versions to a specified location. The task takes any file type as input. Java class files are instrumented. Archives (jar, war, ear etc. or Pack200) are searched recursively for class files which then get instrumented. All other files are copied without modification.

    <jacoco:instrument destdir="target/classes-instr">
        <fileset dir="target/classes" includes="**/*.class"/>
    </jacoco:instrument>

The task definition can contain any number of resource collection types and has the following mandatory attribute:

Attribute | Description | Default
`destdir` | Directory location to write the instrumented files to. | none (required)
`removesignatures` | If set to `true` all signature related information is stripped from JARs. This is typically necessary as instrumentation breaks the signatures of the original class files. | `true`