JaCoCo - Build

# Build

The JaCoCo build is based on Maven and can be locally executed on every machine with a proper environment setup. In particular you need a Maven 3 installation. Developers are encouraged to run the build before every commit to ensure consistency of the source tree.

## Running the Build

The build can be started by executing the following command with `./org.jacoco.build/` as the working directory:

      mvn clean install

Total build time is typically around 3 minutes, however first build might take more time, because Maven should download plugins and dependencies. The download ZIP will be created at the following location:

      ./jacoco/target/jacoco-x.y.z.qualifier.zip

## Running Quick Build without Tests

It is not recommended, however possible to the run build without any tests:

      mvn clean install -DskipTests

## Testing with different JDKs

Target Java version for JaCoCo builds is 1.5, however for verification purposes you can execute tests using other versions. In order to do so, first you should create file `toolchains.xml` in `~/.m2/` directory. Here is an example of such file. For more information see Maven Guide to Using Toolchains.

    <?xml version="1.0" encoding="UTF8"?>
    <toolchains>
      <toolchain>
        <type>jdk</type>
        <provides>
          <id>java15</id>
          <version>1.5</version>
          <vendor>sun</vendor>
        </provides>
        <configuration>
          <jdkHome>/usr/lib/jvm/sun-jdk-1.5</jdkHome>
        </configuration>
      </toolchain>
      <toolchain>
        <type>jdk</type>
        <provides>
          <id>java16</id>
          <version>1.6</version>
          <vendor>sun</vendor>
        </provides>
        <configuration>
          <jdkHome>/usr/lib/jvm/sun-jdk-1.6</jdkHome>
        </configuration>
      </toolchain>
      <toolchain>
        <type>jdk</type>
        <provides>
          <id>java17</id>
          <version>1.7</version>
          <vendor>sun</vendor>
        </provides>
        <configuration>
          <jdkHome>/usr/lib/jvm/sun-jdk-1.7</jdkHome>
        </configuration>
      </toolchain>
      <toolchain>
        <type>jdk</type>
        <provides>
          <id>java18</id>
          <version>1.8</version>
          <vendor>sun</vendor>
        </provides>
        <configuration>
          <jdkHome>/usr/lib/jvm/sun-jdk-1.8</jdkHome>
        </configuration>
      </toolchain>
      <toolchain>
        <type>jdk</type>
        <provides>
          <id>java19</id>
          <version>1.9</version>
          <vendor>sun</vendor>
        </provides>
        <configuration>
          <jdkHome>/usr/lib/jvm/sun-jdk-1.9</jdkHome>
        </configuration>
      </toolchain>
    </toolchains>

Now you should be able to execute maven build with specified version of JDK:

      mvn clean install -Djdk.version=version

Location of `toolchains.xml` can be set via an option:

      mvn --toolchains path clean install -Djdk.version=version

Also Eclipse Compiler for Java can be used for compilation:

      mvn clean install -Decj

In addition JaCoCo can be compiled for higher class file versions than 1.5 specifying the property `bytecode.version`. Note that in this case the version of the JVM running Maven must be at least the version of the specified bytecode version as this JVM is also running the tests. Combining these options JaCoCo is regularly tested with the following setups:

- Maven with 1.5 JDK: `mvn clean install -Djdk.version=1.5 -Dbytecode.version=1.5`
- Maven with 1.6 JDK: `mvn clean install -Djdk.version=1.6 -Dbytecode.version=1.6`
- Maven with 1.7 JDK: `mvn clean install -Djdk.version=1.7 -Dbytecode.version=1.7`
- Maven with 1.8 JDK: `mvn clean install -Djdk.version=1.8 -Dbytecode.version=1.8`
- Maven with 1.8 JDK: `mvn clean install -Djdk.version=1.8 -Dbytecode.version=1.8 -Decj`
- Maven with 1.9 JDK: `mvn clean install -Djdk.version=1.9 -Dbytecode.version=1.9`