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Span IDs

Overview​

Starting from version 6.1.0, sentry-testkit provides support for spanId and parentSpanId properties in your Sentry reports. These IDs are essential for performance monitoring and distributed tracing, allowing you to track the relationships between various spans and transactions in your application.

What are Span IDs?​

In the context of distributed tracing:

  • spanId: A unique identifier for a specific operation or unit of work within your application. Each span represents a single operation, such as a function call or a database query.

  • parentSpanId: A reference to the parent span that initiated the current operation. This creates a hierarchical relationship between spans, allowing you to understand the full context of operations.

Accessing Span IDs in Tests​

You can access these properties in your test assertions:

const sentryTestkit = require('sentry-testkit')
const { testkit } = sentryTestkit()

// After your code triggers a Sentry event
const reports = testkit.reports()
const lastReport = reports[reports.length - 1]

// Access span IDs
console.log(lastReport.spanId) // Unique identifier for this span
console.log(lastReport.parentSpanId) // Reference to parent span (if exists)

Example Use Case: Testing Trace Relationships​

You can use these IDs to verify that your application correctly creates parent-child relationships between operations:

test('should create child spans with correct parent references', async () => {
  // Trigger a parent operation that creates child spans
  await performParentOperationWithChildren()

  const reports = testkit.reports()

  // Find the parent span
  const parentReport = reports.find(r => r.transaction === 'parentOperation')

  // Verify child spans reference the parent
  const childReports = reports.filter(
    r => r.parentSpanId === parentReport.spanId
  )

  expect(childReports.length).toBeGreaterThan(0)
  expect(childReports[0].transaction).toBe('childOperation')
})

Integration with Transactions​

Span IDs work seamlessly with Sentry's transaction API. When working with performance monitoring:

const transaction = Sentry.startTransaction({ name: 'My Transaction' })
Sentry.configureScope(scope => scope.setSpan(transaction))

// Later in your tests
expect(testkit.transactions()[0].spanId).toBeDefined()

This feature enhancement makes it easier to test distributed tracing functionality in your applications while using sentry-testkit.