@mantaq/test

`createTestHarness(actor)`

function createTestHarness<C>(actor: AnyActor<C>): TestHarness<C>;

Instruments actor for testing. Builds state graph, wraps send to record history.

const harness = createTestHarness(checkout);
harness.send(submitBasicInfo.create());
harness.assertStateVisited("shippingAddress");

`computeCoverage(graph, history)`

function computeCoverage(graph: ActorGraph, history: History): CoverageReport;

Compares graph against history. Returns state, transition, and effect coverage as totals, visited counts, and uncovered paths. Used internally by harness.coverage().

const report = computeCoverage(graph, history);
report.percent.states; // 0–100

`TestHarness`

interface TestHarness<C> {
  actor: AnyActor<C>;
  graph: ActorGraph;
  history: History;

  send(event: { type: string; payload?: unknown }): void;
  state: AnyActor["state"];
  snapshot(): Snapshot<C>;
  context: C | undefined;

  assertAllStatesVisited(): void;
  assertAllTransitionsVisited(): void;
  assertStateVisited(stateName: string): void;
  assertStateNeverVisited(stateName: string): void;
  assertTransitionVisited(from: string, event: string): void;
  assertTransitionNeverVisited(from: string, event: string): void;
  assertContextNever(predicate: (context: unknown) => boolean): void;
  assertEffectRan(stateName: string): void;
  assertEffectNeverRan(stateName: string): void;

  wasStateVisited(stateName: string): boolean;
  wasTransitionVisited(from: string, event: string): boolean;
  wasEffectRun(stateName: string): boolean;

  coverage(): CoverageReport;
  reset(): void;
}

Assert methods

All throw on failure.

Method	What
`assertAllStatesVisited()`	Every graph node (non-`__initial__`) was hit
`assertAllTransitionsVisited()`	Every graph edge (non-internal, non-undetermined) hit
`assertStateVisited(name)`	Named state was entered at least once
`assertStateNeverVisited(name)`	Named state was never entered
`assertTransitionVisited(from, event)`	`(from, event)` pair fired
`assertTransitionNeverVisited(from, event)`	Pair never fired
`assertContextNever(fn)`	Predicate does not match current context
`assertEffectRan(name)`	Effect for named state ran
`assertEffectNeverRan(name)`	Effect for named state never ran

Query methods

Boolean checks, no throw.

Method	What
`wasStateVisited(name)`	State entered?
`wasTransitionVisited(from, event)`	Transition fired?
`wasEffectRun(name)`	Effect ran?

`CoverageReport`

interface CoverageReport {
  states: { total: number; visited: number; uncovered: string[] };
  transitions: {
    total: number;
    visited: number;
    uncovered: Array<{ from: string; event: string }>;
  };
  effects: { total: number; ran: number; unexecuted: string[] };
  percent: { states: number; transitions: number; effects: number };
}

Types

Type	What
`TestHarness`	Instrumented actor with assertions and coverage
`CoverageReport`	Numeric coverage with uncovered paths