fix: remove contradictory process.exit unhandledRejection handler

[ionfwsrijan]

Problem

server.js registers two global unhandledRejection listeners with opposite intents:

1. Line 7–9: logs the error and keeps the server running.
2. Lines ~200–205: logs and calls process.exit(1), killing the entire server.

Because both are attached to the same event, any unhandled rejection kills the whole process — contradicting the intent of the first handler.

Fix

Removed the second, process.exit(1)-based handler. Exactly one log-and-continue unhandledRejection policy now remains; uncaughtException still exits deliberately as before.

Files changed

• backend/server.js — removed the exit-based unhandledRejection handler.
• backend/tests/unhandledRejection.policy.unit.test.js — new test asserting exactly one unhandledRejection listener exists and it does not call process.exit.

Testing

npx vitest run tests/unhandledRejection.policy.unit.test.js — 2/2 passing.

Closes #1441

Removes the duplicate unhandledRejection handler and preserves the log-and-continue policy. Adds tests that verify one listener exists and that it does not call process.exit.

[coderabbitai]

📝 Walkthrough

Walkthrough

The duplicate unhandledRejection handler was removed from server.js. Vitest coverage verifies that one listener remains and that the handler does not terminate the process.

Changes

Unhandled rejection policy

Layer / File(s)	Summary
Retain one non-terminating rejection policy backend/server.js, backend/tests/unhandledRejection.policy.unit.test.js	Removed the duplicate handler that called process.exit(1). Added tests for one registered listener and non-terminating behavior.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the primary change: removing the contradictory process.exit unhandledRejection handler.
Linked Issues check	✅ Passed	The changes satisfy [#1441] by retaining one log-and-continue listener, removing process.exit(1), and adding focused tests.
Out of Scope Changes check	✅ Passed	The modified server code and added tests directly support the linked issue objectives, with no unrelated changes identified.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/tests/unhandledRejection.policy.unit.test.js`:
- Around line 16-25: The tests in unhandledRejection.policy.unit.test.js must
validate runtime behavior instead of matching backend/server.js source text.
Move the unhandledRejection registration into a side-effect-free module, import
it in the test, inspect process.listeners("unhandledRejection") to verify one
registered listener, invoke that listener, and spy on console.error and
process.exit to assert the required logging and non-exit policy without starting
the server.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 74e0ad48-1d55-4ec3-9574-112a1dfd3841

📥 Commits

Reviewing files that changed from the base of the PR and between 8acb5b8 and edf9911.

📒 Files selected for processing (2)

• backend/server.js
• backend/tests/unhandledRejection.policy.unit.test.js

💤 Files with no reviewable changes (1)

• backend/server.js

[coderabbitai]

🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -eu

printf '%s\n' '--- backend/tests/unhandledRejection.policy.unit.test.js ---'
cat -n backend/tests/unhandledRejection.policy.unit.test.js

printf '%s\n' '--- backend/server.js relevant lines ---'
nl -ba backend/server.js | sed -n '1,80p'

printf '%s\n' '--- references to the policy and test setup ---'
rg -n --glob '!node_modules' 'unhandledRejection|console\.error|process\.exit|serverSource' backend package.json 2>/dev/null | head -200

Repository: Canopus-Labs/PrepPilot

Length of output: 10123

---

🏁 Script executed:

#!/bin/bash
set -eu

printf '%s\n' '--- backend/server.js lines 1-25 and 175-205 ---'
sed -n '1,25p;175,205p' backend/server.js

printf '%s\n' '--- project module and test configuration ---'
for f in package.json backend/package.json vitest.config.js backend/vitest.config.js; do
  if [ -f "$f" ]; then
    echo "--- $f ---"
    cat "$f"
  fi
done

printf '%s\n' '--- server.js imports and startup calls ---'
rg -n '^(import|const .*require)|listen\(|connect\(|start|app\.' backend/server.js | head -120

Repository: Canopus-Labs/PrepPilot

Length of output: 5718

---

🏁 Script executed:

#!/bin/bash
set -eu

python3 - <<'PY'
from pathlib import Path
import re

test_source = Path("backend/tests/unhandledRejection.policy.unit.test.js").read_text(encoding="utf-8-sig")
server_source = Path("backend/server.js").read_text(encoding="utf-8")

pattern = re.compile(r'''process\.on\(\s*["']unhandledRejection["']''')

def assertions(source):
    matches = pattern.findall(source)
    start = source.find('"unhandledRejection"')
    end = source.find("unhandledRejection") + 300
    block = source[start:end]
    return len(matches), start, end, "process.exit" in block

variants = {
    "current": server_source,
    "single-quoted event": server_source.replace(
        'process.on("unhandledRejection"', "process.on('unhandledRejection'"
    ),
    "uses process.once": server_source.replace(
        'process.on("unhandledRejection"', 'process.once("unhandledRejection"'
    ),
    "exit after window": server_source.replace(
        '  console.error("Unhandled Promise Rejection:", err);',
        '  console.error("Unhandled Promise Rejection:", err);\\n' + " " * 400 + "process.exit(1);",
    ),
    "missing console.error": server_source.replace(
        '  console.error("Unhandled Promise Rejection:", err);\\n', ""
    ),
}

print("test source uses runtime listener APIs:", bool(re.search(
    r'process\.(listeners|once|addListener)|import\s+.*server', test_source
)))
for name, source in variants.items():
    count, start, end, has_exit = assertions(source)
    print(f"{name}: matches={count}, start={start}, end={end}, detects_exit={has_exit}")

server_lines = server_source.splitlines()
print("server starts listening:", any("app.listen(" in line for line in server_lines))
print("policy logs:", any("Unhandled Promise Rejection:" in line for line in server_lines))
PY

Repository: Canopus-Labs/PrepPilot

Length of output: 594

---

Test the registered policy at runtime, not with source-text matching.

The current tests can pass when the handler uses process.once, does not register, omits console.error, or calls process.exit outside the 300-character slice. Importing backend/server.js starts the server, so move the registration to a side-effect-free module, inspect process.listeners("unhandledRejection"), invoke the listener, and spy on console.error and process.exit.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/tests/unhandledRejection.policy.unit.test.js` around lines 16 - 25,
The tests in unhandledRejection.policy.unit.test.js must validate runtime
behavior instead of matching backend/server.js source text. Move the
unhandledRejection registration into a side-effect-free module, import it in the
test, inspect process.listeners("unhandledRejection") to verify one registered
listener, invoke that listener, and spy on console.error and process.exit to
assert the required logging and non-exit policy without starting the server.