NixOS Machines

Use machine when behavior depends on a NixOS VM. Machine actions automatically create an empty default VM. Add machine.configure only when the test needs NixOS modules.

test."service becomes healthy" = { machine }: [
  (machine.configure {
    modules = [
      self.nixosModules.default
      { services.example.enable = true; }
    ];
  })

  (expect (machine.service "example.service")).toBeActive
  (expect (machine.file "/run/example/ready")).toExist
  ((expect (machine.http.get "http://localhost/health")).toHaveStatus 200)
];

Semantic System State

Use semantic fixtures for services, filesystems, endpoints, HTTP, users, and containers. Their matchers retry until the expected state appears.

[
  (expect (machine.service "example.service")).toBeActive
  ((expect (machine.service "example.service").logs).toContain "configuration loaded")
  ((expect (machine.file "/var/lib/example")).toBeOwnedBy "example")
  (expect (machine.endpoint.tcp 8080)).toBeReachable
]

Terminal Interaction In A VM

machine also implements the terminal interface:

[
  (machine.open "example-tui")
  (machine.press "start<enter>")
  (expect (machine.getByText "running")).toBeVisible
]

For exploratory access, guest shells, SSH, and forwarded ports, see Debugging.