fix: v8 coverage ranges that fall on \n characters cause exceptions #96
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When a file has dos line endings \r\n we found a few instances in a large codebase where v8 would report the position of the \n as startCol for a range. This would cause the starting column supplied to sourceMap.originalPositionFor to be a -1 because the startColumns of the transpiled source lines were calculated as endCol + length of line break sequence. To replicate this condition, revert the fix but run the new unit test. The call to `applyCoverage` will crash. While the unit test range was hand crafted by me for this particular example, we saw this coming up in the wild. This change clamps the supplied value to max 0 and adds a test fixture (force encoded as \r\n) to test for it.
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When a file has dos line endings \r\n we found a few instances in a large codebase
where v8 would report the position of the \n as startCol for a range. This would
cause the starting column supplied to
sourceMap.originalPositionForto be a -1because the startColumns of the transpiled source lines were calculated as
endCol + length of line break sequence. This value is invalid causing
sourceMap.originalPositionForto throw withColumn numbers must be >= 0.To replicate this condition, revert the fix but run the new unit test. The
call to
applyCoveragewill crash. While the unit test range was handcrafted by me for this particular example, we saw this coming up in the
wild.
This change clamps the supplied value to a min of 0 and adds a test
fixture (force encoded as \r\n) to test for it. The encoding are maintained
across varying gitconfigs via entries in
.gitattributes