| # Coverage Example |
| |
| This example demonstrates Kotlin code coverage with Bazel using `bazel coverage`. |
| |
| ## Background |
| |
| This example verifies the fix for [issue #1447](https://github.com/bazelbuild/rules_kotlin/issues/1447), which addresses a JaCoCo version mismatch between `rules_kotlin` and `rules_java 9.3.0+`. |
| |
| The issue occurred because the kotlin_worker.jar was compiled against JaCoCo 0.8.11, but `rules_java 9.3.0` uses JaCoCo 0.8.14. This caused a `NoClassDefFoundError` when running `bazel coverage` on Kotlin targets. |
| |
| ## The Fix |
| |
| The fix reorders `runtime_deps` to put `@bazel_tools//tools/jdk:JacocoCoverage` **before** the worker. This ensures the newer JaCoCo classes from Bazel's tools are loaded first, taking precedence over the older version bundled in the worker. |
| |
| ## Running the Example |
| |
| ```bash |
| cd examples/coverage |
| bazel coverage --combined_report=lcov //:coverage_test |
| ``` |
| |
| To view the HTML report: |
| ```bash |
| genhtml bazel-out/_coverage/_coverage_report.dat -o coverage_html |
| ``` |
| |
| ## Expected Results |
| |
| The coverage test should run successfully without any `NoClassDefFoundError` exceptions, and generate coverage reports in `bazel-out/_coverage/`. |
