reproduce-bug

Bug Reproduction Framework

Given a Linear ticket context ($ARGUMENTS), systematically reproduce the bug with a failing regression test.

Step 1: Parse Signals

Extract the following from the provided ticket context:

• Error message / stack trace (if provided)
• Reproduction steps (if provided)
• Workflow JSON (if attached)
• Affected area (node, execution engine, editor, API, config, etc.)
• Version where it broke / last working version

Step 2: Route to Test Strategy

Based on the affected area, pick the test layer and pattern:

Area	Test Layer	Pattern	Key Location
Node operation	Vitest unit	NodeTestHarness + nock	packages/nodes-base/nodes/*/test/
Node credential	Vitest unit	vitest-mock-extended	packages/nodes-base/nodes/*/test/
Trigger webhook	Vitest unit	mock IHookFunctions + vi.mock GenericFunctions	packages/nodes-base/nodes/*/test/
Binary data	Vitest unit	NodeTestHarness assertBinaryData	packages/core/nodes-testing/
Execution engine	Vitest integration	WorkflowRunner + DI container	packages/cli/src/__tests__/
CLI / API	Vitest integration	setupTestServer + supertest	packages/cli/test/integration/
Config	Vitest unit	GlobalConfig + Container	packages/@n8n/config/src/configs/__tests__/
Editor UI	Vitest	Vue Test Utils + Pinia	packages/frontend/editor-ui/src/**/__tests__/
E2E / Canvas	Playwright	Test containers + composables	packages/testing/playwright/

Step 3: Locate Source Files

Find the source code for the affected area:

1. Search for the node/service/component mentioned in the ticket
2. Find the GenericFunctions file (common bug location for nodes)
3. Check for existing test files in the same area
4. Look at recent git history on affected files (git log --oneline -10 -- <path>)

Step 4: Trace the Code Path

Read the source code and trace the execution path that triggers the bug:

• Follow the call chain from entry point to the failure
• Identify the specific line(s) where the bug manifests
• Note any error handling (or lack thereof) around the bug

Step 5: Form Hypothesis

State a clear, testable hypothesis:

• "When [input/condition], the code does [wrong thing] because [root cause]"
• Identify the exact line(s) that need to change
• Predict what the test output will show

Step 6: Find Test Patterns

Look for existing tests in the same area:

1. Check test/ directories near the affected code
2. Identify which mock/setup patterns they use
3. Use the same patterns for consistency
4. If no tests exist, find the closest similar node/service tests as a template

Step 7: Write Failing Test

Write a regression test that:

• Uses the patterns found in Step 6
• Targets the specific hypothesis from Step 5
• Includes a comment referencing the ticket ID
• Asserts the CORRECT behavior (test will fail on current code)
• Also includes a "happy path" test to prove the setup works

Step 8: Run and Score

Run the test from the package directory (e.g., cd packages/nodes-base && pnpm test <file>).

Classify the result:

Confidence	Criteria	Output
CONFIRMED	Test fails consistently, failure matches hypothesis	Reproduction Report
LIKELY	Test fails but failure mode differs slightly	Report + caveat
UNCONFIRMED	Cannot trigger the failure	Report: what was tried
SKIPPED	Hit a hard bailout trigger	Report: why skipped
ALREADY_FIXED	Bug no longer reproduces on current code	Report: when fixed

Step 9: Iterate or Bail

If UNCONFIRMED after first attempt:

• Revisit hypothesis — re-read the code path
• Try a different test approach or layer
• Maximum 3 attempts before declaring UNCONFIRMED

Hard bailout triggers (stop immediately):

• Requires real third-party API credentials
• Race condition / timing-dependent
• Requires specific cloud/enterprise infrastructure
• Requires manual UI interaction that can't be scripted

Output: Reproduction Report

Present findings in this format:

---

Ticket: [ID] — [title] Confidence: [CONFIRMED | LIKELY | UNCONFIRMED | SKIPPED | ALREADY_FIXED]

Root Cause

[1-2 sentences explaining the bug mechanism]

Location

File	Lines	Issue
path/to/file.ts	XX-YY	Description of the problem

Failing Test

path/to/test/file.test.ts — X/Y tests fail:

1. test name — [failure description]

Fix Hint

[Pseudocode or description of the fix approach]

---

Important

• DO NOT fix the bug — only reproduce it with a failing test
• Leave test files in place as evidence (don't commit unless asked)
• Run tests from the package directory (e.g., pushd packages/nodes-base && pnpm test <file> && popd)
• Always redirect build output: pnpm build > build.log 2>&1
• DO NOT look at existing fix PRs — the goal is to reproduce from signals alone