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Concepts ​

Servers ​

A mock server is a real server: mockhttp.Server for HTTP, mockgrpc.Server for gRPC. A test starts one, adds mocks, and sends it requests through the code under test. Setup() configures it, and its settings can also come from a .vlatterc file and VLATTE_* variables: see Configuration.

Mocks ​

A mock is three things:

  1. Matchers that say which requests it answers: a method, a path, a header, a field of the body. See HTTP matching, gRPC matching, and the matchers both share.
  2. A reply that says how it answers: a status, headers, a body, a stream of messages, a proxy to a real service. See HTTP replies and gRPC replies.
  3. Mock features that both protocols share: an ID and a name, a priority, Times and Once, delays, scenarios, and events such as webhooks. See Mock lifecycle.
go
m.MustMock(mockhttp.Postf("/orders").            // matchers
	Header("Content-Type", match.Equal("application/json")).
	Priority(1).Times(2).                        // mock features
	Reply(mockhttp.Created().JSON(map[string]any{"id": 1}))) // reply

When several mocks match a request, the one with the lowest priority number answers.

Mock files ​

Mocks can also live in YAML or JSON files, with the same parts as keys: request, response, priority, scenario, on_complete. A server loads them on start from its work directory, and the vlatte command serves them. See HTTP mock files and gRPC mock files.

The work directory ​

A server keeps its own files under testdata/vlatte: mock files in _mocks, recordings in _mocks_recorded, and the CLI's admin mocks and journal. See Work directory.

When nothing matches ​

A server answers a request no mock matched itself, in a way that never looks like a mock's answer: HTTP 418 with a VLatte-Error header, gRPC NotFound. It lists the mocks that came closest. See HTTP troubleshooting and gRPC troubleshooting.