TST-34: Domain entity state machine exhaustive tests — CommandRun, ArchiveItem, ChatSession

[Chris0Jeky]

Context

Several domain entities have rich state machines with transition guards that are completely untested. These are the core business rules of the system.

Entities and Their State Machines

CommandRun (6 states, 5 transitions, 0 tests)

State machine: Queued → Running → Completed/Failed/TimedOut/Cancelled

Test matrix:

From	Action	Expected
Queued	Start()	Running
Queued	Fail("msg")	Failed
Queued	Cancel()	Cancelled
Running	Complete(0)	Completed
Running	Complete(1)	Completed (non-zero exit)
Running	Fail("msg")	Failed
Running	Timeout()	TimedOut
Running	Cancel()	Cancelled
Completed	Start()	throws
Completed	Complete(0)	throws
Failed	Start()	throws
TimedOut	Cancel()	throws
Cancelled	Start()	throws

Also test:

• Constructor rejects empty templateName, Guid.Empty userId, empty correlationId
• Fail("") throws (empty error message)
• SetOutputPreview with string > 1000 chars throws
• SetOutputPreview(null) succeeds (nullable)
• SetTruncated() is idempotent
• AddLog() adds to Logs collection and calls Touch()

ArchiveItem (4 states, 4 transitions, 0 tests)

State machine: Available → Restored/Expired/Conflict

Test matrix:

From	Action	Expected
Available	MarkAsRestored(userId)	Restored
Available	MarkAsExpired()	Expired
Available	MarkAsConflict()	Conflict
Restored	ResetToAvailable()	throws
Expired	ResetToAvailable()	Available
Conflict	ResetToAvailable()	Available
Restored	MarkAsExpired()	throws
Expired	MarkAsRestored(userId)	throws

Also test:

• Constructor validates entityType must be "board", "column", or "card" — test "task", "", null
• name.Length > 200 throws
• Guid.Empty for various ID parameters throws
• Empty snapshotJson throws
• MarkAsRestored(Guid.Empty) throws

UserPreference (untested)

• DismissOnboarding() / ReplayOnboarding() / RecordOnboardingCompletion() idempotent guard
• Verify RecordOnboardingCompletion can only be called once

NotificationPreference (untested)

• Update() method validates new values

ChatSession (untested)

• Session lifecycle and message accumulation
• Any state-dependent behavior

CardLabel and CardCommentMention (untested)

• Construction invariants

Implementation Notes

• These are pure domain tests — no mocking needed, just construct entities and assert
• Follow existing pattern in Taskdeck.Domain.Tests (e.g., BoardTests, CardTests)
• One test class per entity
• Use [Theory] with [InlineData] for the transition matrix
• Verify Touch() is called (UpdatedAt changes) on every mutation