Post increment exit code under set-e cause incomplete coverage report

[objctp]

Q	A
OS	macOS
Shell & version	bash 5.3.9
bashunit version	0.34.1

Summary

LCOV (--coverage-report) and HTML (--coverage-report-html) coverage reports are incomplete or missing due to ((var++)) post-increment operator causing early script termination under set -e. The console coverage report works correctly.

Current behavior

LCOV report (lcov.info): Only contains TN: and SF: headers with no DA:, LF:, LH:, or end_of_record entries:

TN:
SF:/path/to/source.sh

HTML report: File HTML is truncated mid-generation (no code lines, function summary table incomplete). index.html missing entirely.

Console coverage output displays correct percentages.

How to reproduce

# Create project structure
mkdir -p /tmp/bug-repro/{lib,tests}
cd /tmp/bug-repro
# 1. Create a source file to be covered
cat > lib/math.sh << 'EOF'
#!/usr/bin/env bash
add() {
 echo $(($1 + $2))
}

multiply() {
 echo $(($1 * $2))
}

divide() {
 if [ "$2" -eq 0 ]; then
 echo "error: division by zero"
 return 1
 fi
 echo $(($1 / $2))
}
EOF

# 2. Create a test file
cat > tests/math_test.sh << 'EOF'
#!/usr/bin/env bash
source lib/math.sh

test_add() {
 assert_equals "5" "$(add 2 3)"
}

test_multiply() {
 assert_equals "6" "$(multiply 2 3)"
}

test_divide() {
 assert_equals "2" "$(divide 6 3)"
}
EOF

# 3. Run with coverage and file reports
bashunit tests/math_test.sh --coverage --coverage-paths "lib/" --coverage-report coverage/lcov.info --coverage-report-html coverage/html

# 4. Check LCOV output
cat coverage/lcov.info
# Shows only TN: and SF: headers

# 5. Check HTML output
ls coverage/html/
# Missing index.html or have incomplete file HTML

Expected behavior

LCOV report should contain complete coverage data:

TN:
SF:/path/to/source.sh
DA:3,0
DA:7,0
...
LF:6
LH:0
end_of_record

HTML report should generate complete index.html and per-file HTML with all code lines, colour-coded by coverage status.

Root cause

In (coverage.sh) report_lcov(), generate_file_html(), and elsewhere, the pattern ((var++)) is used. Under set -e, when var is 0, post-increment evaluates the old value (0), which is falsy in bash arithmetic, causing the expression to return exit code 1. This terminates the script immediately.

The { ... } > "$output_file" redirect swallows the error, making the failure silent — only incomplete output is visible.

Fix: Change ((var++)) to ((++var)) (pre-increment), which always returns 0 when incrementing from 0→1, avoiding the set -e trigger while producing identical side effects.