Coverage provides coverage data collection, manipulation, and formatting for Dart.


collect_coverage.dart collects coverage JSON from the Dart VM Observatory. format_coverage.dart formats JSON coverage data into either LCOV or pretty-printed format.

Collecting coverage from the VM

dart --enable-vm-service:NNNN --pause_isolates_on_exit script.dart
dart bin/collect_coverage.dart --port=NNNN -o coverage.json --resume-isolates

The --pause_isolates_on_exit VM flag is used to pause isolates on exit to allow coverage to be collected. If collect_coverage.dart is invoked before the script from which coverage is to be collected, it will wait until it detects a VM observatory port to which it can connect. An optional --connect-timeout may be specified (in seconds). When collecting coverage from a VM run with the --pause_isolates_on_exit flag set, the --wait-paused flag may be enabled, causing collect_coverage.dart to wait until all isolates are paused before collecting coverage.

Collecting coverage from Dartium

dartium --remote-debugging-port=NNNN
# execute code in Dartium
dart bin/collect_coverage.dart --port=NNNN -o coverage.json

As noted above, collect_coverage.dart may be invoked before Dartium, in which case it will wait until it detects a Dartium remote debugging port, up to the (optional) timeout.

Formatting coverage data

dart bin/format_coverage.dart --package-root=app_package_root -i coverage.json

where app_package_root is the package-root of the code whose coverage is being collected. If --sdk-root is set, Dart SDK coverage will also be output.