Testing overview

Connector bugs are expensive to find in production: a crawl either indexes nothing, indexes the wrong thing, or — worst case — deletes documents it should have kept. The SDK's testing tools exist so you find those problems before pointing a connector at a real instance.

Testing progresses through three phases. Each phase swaps exactly one dependency from mocked to real, so a failure tells you which layer broke.

1Unit

SourceMocked

GleanMocked

SpeedMilliseconds

CredentialsNone

run_connector with a static data client. No network at all.

Does transform() produce the documents I expect?

2Integration

SourceReal

GleanMocked

SpeedFast after first run

CredentialsSource only

Records real source responses to NDJSON, then replays them offline.

Does my data client parse what the source really returns?

3End-to-end

SourceReal

GleanReal

SpeedSlow

CredentialsSource + Glean

No mocking. Uploads to whatever GLEAN_SERVER_URL points at.

Does the whole thing work against a live instance?

Most of your tests should be Phase 1. Phase 2 catches the class of bug you can't mock your way to — a source field that's null more often than the docs suggest. Phase 3 is a pre-release check, not something you run on every commit.

The harness

TestHarness wraps a connector and drives all three phases:

from glean.indexing.testing import TestConfig, TestHarness

harness = TestHarness(
    connector=my_connector,
    config=TestConfig(),
    clients={"data_client": real_data_client},   # required for Phase 2 and 3
)

clients maps connector attribute names to data client instances. Keys must match real attributes on the connector — AttributeError otherwise. Phase 1 doesn't need it.

Output validation

run_connector() and the harness both run validate_connector_output() automatically, which catches structural mistakes — a document whose datasource doesn't match the connector, a missing required field — and raises ConnectorOutputValidationError. You get those checks without writing them.

Testing permissions

Every phase can assert on ACLs. Because permissions are the highest-risk part of a connector, test the negative case explicitly — see Permissions.