@tracegraph/jest

TraceGraph reporter for Jest. Produces per-test .trace.json files (capture level 5), giving each test case its own isolated trace with full test-lifecycle events. Drop-in addition to any existing Jest setup.

What's in this package

| Export | Description | |--------|-------------| | TraceGraphJestReporter | Jest reporter class — implements onTestFileStart, onTestStart, onTestResult, and onRunComplete to write one trace per test |

The package also provides a default export so Jest can load it via the short-form string '@tracegraph/jest' without needing the class name.

Installation

npm install -D @tracegraph/jest jest

Usage

Add to jest.config.js

module.exports = {
  reporters: [
    'default',
    '@tracegraph/jest',
  ],
};

With options (currently none required, reserved for future use):

module.exports = {
  reporters: [
    'default',
    ['@tracegraph/jest', {}],
  ],
};

Via tracegraph run (auto-injection)

tracegraph run -- npx jest
# → "@tracegraph/jest reporter auto-injected"

tracegraph run detects Jest in the command and appends --reporters=default --reporters=@tracegraph/jest automatically unless the reporter is already present.

Direct CLI usage

npx jest --reporters=default --reporters=@tracegraph/jest

What the reporter captures

Each test trace includes:

• test_file event — the test file path and suite structure
• test_run event per test — test name, pass/fail/skip/todo status, and duration in milliseconds
• error event on test failure — error type and message extracted from Jest's test result
• All events emitted by traceFunction / traceMethod / traceExpress instrumentation running inside the test body

Trace isolation

Each test in a test file gets its own traceId. Events are written to separate .tmp files per test and atomically finalised to .trace.json files when the test completes.

Requirements

• Jest ≥ 27.0.0
• TRACEGRAPH_ENABLED=1 and TRACEGRAPH_RUN_DIR set in the environment (set automatically by tracegraph run)