レポーターの出力が空の文字列であるため、travis ci は失敗します。
NODE_ENV=test YOURPACKAGE_COVERAGE=1 mocha --compilers coffee:coffee-script/register --require blanket --reporter mocha-lcov-reporter | ./node_modules/coveralls/bin/coveralls.js
私の地域では問題なく動作します。
> mocha --compilers coffee:coffee-script/register --require blanket --reporter mocha-lcov-reporter | ./node_modules/coveralls/bin/coveralls.js
[error] "2015-04-26T12:41:57.904Z" 'error from lcovParse: ' 'Failed to parse string'
[error] "2015-04-26T12:41:57.906Z" 'input: ' ''
[error] "2015-04-26T12:41:57.906Z" 'error from convertLcovToCoveralls'