Generate code coverage in TravisCI build and send it to Codecov

.travis.yml

# Workaround which:
#   * Starts observatory in background
#   * Runs the test suite
#   * Collects coverage and sends it to Codecov
#
# Someday the `test` package will support observatory and below steps 
# could be simplified.
#
# Prerequisites:
#   * Have Travis CI build for your repo
#   * Have `test/all.dart` which executes all-the-tests
#   * Have Codecov account with your repo enabled in it.
#
# It is an example for running VM tests only.

sudo: false

language: dart

script:
  - pub run test
  - pub global activate coverage
  - dart --observe=8111 test/all.dart &
  - sleep 1 # make sure this is longer then time needed to run the whole test suite
  - pub global run coverage:collect_coverage --port=8111 -o coverage.json --resume-isolates
  - pub global run coverage:format_coverage --package-root=packages --report-on lib --in coverage.json --out lcov.info --lcov

after_success:
  - bash <(curl -s https://codecov.io/bash)