Offline fixtures

Use LibTmux.Snapshot.Fixture to build ordinary observation records and validate their relationships. No fixture operation starts tmux, opens a socket or allocates an operational Server.

The complete program below tests a pane-selection policy against one physical window appearing at two session indices. Run it from a provisioned checkout:

$ cabal run --verbose=0 offline-graph

For a separate Cabal application, copy Main.hs and its package file. Save the pinned source project as cabal.project, provision its dependencies, then run the same command.

{-# LANGUAGE OverloadedRecordDot #-}
{-# LANGUAGE OverloadedStrings #-}

-- | Test a pane-selection policy without starting tmux or opening a socket.
module Main (main) where

import Data.Bifunctor (first)
import LibTmux qualified as Tmux
import LibTmux.Snapshot.Fixture qualified as F
import System.Exit (die)
import System.OsString.Posix qualified as Os

main :: IO ()
main = do
  snapshot <- either die pure buildSnapshot
  print (Tmux.snapshotOrigin snapshot)
  print
    [ (Tmux.renderPaneId (Tmux.paneId pane.ref), Tmux.dimensionValue pane.width)
    | pane <- Tmux.panes snapshot
    , pane.active
    , Tmux.dimensionValue pane.width >= 120
    ]
  print (length (Tmux.windows snapshot), length (Tmux.paneOccurrences snapshot))

buildSnapshot :: Either String Tmux.Snapshot
buildSnapshot = do
  version <- checked (Tmux.parseVersion "3.8")
  sid <- checked (Tmux.parseSessionId "$1")
  wid <- checked (Tmux.parseWindowId "@2")
  pid <- checked (Tmux.parsePaneId "%3")
  width <- checked (Tmux.mkDimension 120)
  height <- checked (Tmux.mkDimension 40)
  paneIndex <- checked (Tmux.mkPaneIndex 0)
  firstIndex <- checked (Tmux.mkWindowIndex 0)
  secondIndex <- checked (Tmux.mkWindowIndex 4)
  let origin = F.fixtureOrigin "reports"
      session = Tmux.Session (F.sessionRef origin sid) "work" 0
      window = Tmux.Window (F.windowRef origin wid) "editor" width height
      pane = Tmux.Pane
        { Tmux.ref = F.paneRef origin pid
        , Tmux.window = window.ref
        , Tmux.index = paneIndex
        , Tmux.width = width
        , Tmux.height = height
        , Tmux.active = True
        , Tmux.dead = False
        , Tmux.title = "editor"
        , Tmux.currentCommand = Os.fromBytestring "ghci"
        , Tmux.currentPath = Os.fromBytestring "/offline/project"
        }
      input = (F.emptyFixture origin version)
        { F.sessions = [session], F.windows = [window], F.panes = [pane]
        , F.windowLinks = [Tmux.WindowLink session.ref firstIndex window.ref True,
                          Tmux.WindowLink session.ref secondIndex window.ref False]
        }
  checked (F.validateFixture origin input)

checked :: Show problem => Either problem value -> Either String value
checked = first show

Program output:

DefinedOffline "reports"
[("%3",120)]
(1,2)

fixtureOrigin creates a named offline namespace. Reuse a name to model successive observations in one test scenario; use different names for independent scenarios. Fixture references never compare equal to references from an adopted Server, even when their native IDs match.

emptyFixture supplies synthetic server metadata and empty collections. Populate its ordinary records, then call validateFixture. It reuses graph and metadata validation, including reference membership, duplicate slots, active selections and attached-client context. A failed input returns FixtureError; it never becomes an empty snapshot. Reading an edited record alone does not validate the graph or update a previously built snapshot. Wire decoding, tmux’s field normalization and transport limits apply to live acquisition. Synthetic values can exercise cases a live capture cannot produce.

SnapshotOrigin distinguishes DefinedOffline from AcquiredFromTmux. Offline snapshots have no acquisition interval. Neither provenance nor an opaque reference proves that a tmux target is currently alive.

The installed consumer check compiles this source against the archived public package and asserts its output. The Hspec cases exercise namespace separation and invalid graphs without a daemon. See capture and recovery for observations acquired from tmux.

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Offline fixtures