chitezh / c8-empty-lines

c8 reporting issue

C8 mistakenly reports lack of coverage for empty lines - sometimes. This only seems to happen to files with export * from ... pattern with a newline preceeding EOF - at least that is the observed pattern. I am not very familiar with the inner workings of c8.

This simple POC of the issue, provides two demonstrations.

Before we get into it, the source is organized to be accessed in two ways:

src/
  index.ts         - an exporter of main.ts (the problem file)
  main.ts          - the simple business end of the code

Installation

git clone https://github.com/sramam/c8-empty-lines
npm install
NODE_V8_COVERAGW=./.c8-data

The successful case - 100% coverage

rm -rf .c8-data .c8-report
npm run build
npm run test-main
npm run report

npm run report     

> c8-empty-lines@1.0.0 report C:\Users\srama\tmp\c8-empty-lines
> c8 report -r lcov -r text --report-dir ./.c8-report

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |
 src      |     100 |      100 |     100 |     100 |
  main.ts |     100 |      100 |     100 |     100 |
 src/test |     100 |      100 |     100 |     100 |
  main.ts |     100 |      100 |     100 |     100 |
----------|---------|----------|---------|---------|-------------------

The trouble case

rm -rf .c8-data .c8-report
npm run build
npm run test-index
npm run report

npm run report

> c8-empty-lines@1.0.0 report C:\Users\srama\tmp\c8-empty-lines
> c8 report -r lcov -r text --report-dir ./.c8-report

-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------|---------|----------|---------|---------|-------------------
All files  |     100 |       80 |     100 |     100 |
 src       |     100 |       75 |     100 |     100 |
  index.ts |     100 |    66.67 |     100 |     100 | 1
  main.ts  |     100 |      100 |     100 |     100 |
 src/test  |     100 |      100 |     100 |     100 |
  index.ts |     100 |      100 |     100 |     100 |
-----------|---------|----------|---------|---------|-------------------