Test keys and fixtures

A test key (lsk_test_…) runs checks on a fixture engine instead of real connections. Results are predictable, marked test: true and never charged. Use it to write and test your integration, including how you handle blocks and failures.

Fixture host names

The outcome depends only on the host name of the URL:

Host name	Every cohort gets
`blocked-dns.fixtures.linkspect.com`	`blocked`, `layer: "dns"`, `method: "redirect"`
`blocked-sni.fixtures.linkspect.com`	`blocked`, `layer: "tls_sni"`, `method: "reset"`
`target-down.fixtures.linkspect.com`	`target_down`
`proxy-failure.fixtures.linkspect.com`	`proxy_failure` with `reason: "exit_changed"`, all measurements excluded
any other host name	`ok`

Paths and query strings do not matter, so https://blocked-sni.fixtures.linkspect.com/checkout?step=2 gives the same result as the bare host. Each measurement in a fixture result has details at GET /v1/measurements/{id}, like a real one.

How long fixture checks take

Profile	Time per cohort	Finishes within `Prefer: wait=30`?
`quick`	2 seconds	yes
`standard`	10 seconds	yes
`deep`	40 seconds	no: you get `202` and poll

A deep fixture check is the easy way to test the 202 path and polling (see Waiting and polling).

Rules that still apply

The fixture engine skips the measuring, not the rules in front of it:

A cohort whose operator has no exits in the catalog gets not_measured with no_vantage.
An http URL, or a port other than 443, gets not_measured with peer_safety in cohorts measured through subscribers' connections. This is our policy to protect the people whose connections carry the measurements.
Bad URLs and targets get the same errors as with a live key.
Test keys do not open real browsers, and do not ask public DNS filters or reputation sources, so user_filters stays empty.

Live keys

Fixture host names never give fixture results with a live key (lsk_live_…). Cohorts that cannot be measured get not_measured and are not charged; a preview (POST /v1/checks:preview) shows them as not_measurable in advance.