A final blankline in a file prevents 100% code coverage

[jaydenseric]

A final newline in a file incorrectly prevents 100% code coverage when using the deno test and deno coverage CLIs.

This is especially a problem because many projects enforce a final newline in files, via EditorConfig (insert_final_newline config), linters, or other means.

To reproduce, in example.js (note the newline at the end):

export default function example() {
  return true;
}

Then, in example_test.js:

import example from "./example.js";

Deno.test("Example.", () => {
  example();
});

Run:

deno test --coverage=cov && deno coverage cov

And note that the final line 4 is reported as uncovered, resulting in 75% code coverage for the file example.js:

running 1 test from file:///[redacted]/demo/example_test.js
test Example. ... ok (8ms)

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out (45ms)

cover file:///[redacted]/demo/example.js ... 75.000% (3/4)
   4 |

If you delete that final newline in example.js, the report changes to 100% code coverage:

running 1 test from file:///[redacted]/demo/example_test.js
test Example. ... ok (8ms)

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out (45ms)

cover file:///[redacted]/demo/example.js ... 100.000% (3/3)

deno --version:

deno 1.11.5 (release, x86_64-apple-darwin)
v8 9.1.269.35
typescript 4.3.2

[caspervonb]

Thanks for the report, in the middle of a major overhaul of the entire thing so these serve as excellent new test fixtures!

Just tagging myself for filtering purposes @caspervonb.

[jaydenseric]

@caspervonb is there a PR that should close this issue to track? This small bug makes code coverage via Deno unusable; perhaps a patch just for this could be pulled out of whatever major refactoring work you're doing, if it's a multi-month epic task?

[caspervonb]

@caspervonb is there a PR that should close this issue to track? This small bug makes code coverage via Deno unusable; perhaps a patch just for this could be pulled out of whatever major refactoring work you're doing, if it's a multi-month epic task?

Will be fixed and shipped soon, sorry for leaving this open for so long but there's pretty much zero interest in coverage from my sponsors.

[jaydenseric]

Can this issue please be reopened since the PR that fixed it got reverted?