fix: synchronize mounted component props

packages/test/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@wrnexus/test",
-  "version": "0.8.11",
+  "version": "0.8.12",
   "private": true,
   "type": "module",
   "main": "src/index.ts",

packages/test/src/index.ts

@@ -205,3 +205,9 @@ export type {
 } from "./advanced.ts";
 export { withDatabaseRollback, createFactory, captureBrowserArtifacts } from "./platform.ts";
 export type { TransactionalDatabase, BrowserArtifactPage } from "./platform.ts";
+export { detectMutations } from "./mutation.ts";
+export type {
+  MutationCase,
+  MutationReport,
+  DetectMutationsOptions,
+} from "./mutation.ts";

packages/test/src/mutation.ts

@@ -0,0 +1,52 @@
+export interface MutationCase<T> {
+  name: string;
+  value: T;
+}
+
+export interface MutationReport<O> {
+  baseline: O;
+  killed: string[];
+  survived: string[];
+}
+
+export interface DetectMutationsOptions<T, O> {
+  baseline: T;
+  mutations: Array<MutationCase<T>>;
+  exercise(value: T): O | Promise<O>;
+  equivalent?(left: O, right: O): boolean;
+}
+
+/**
+ * Run the same behavioural probe against a baseline and explicit mutations.
+ * A mutation survives when the observable result is unchanged. The helper
+ * throws with every survivor by default, making it suitable for an ordinary
+ * Bun test and CI without a second runner or source-rewriting process.
+ */
+export async function detectMutations<T, O>(
+  options: DetectMutationsOptions<T, O>,
+): Promise<MutationReport<O>> {
+  if (!options.mutations.length) {
+    throw new Error("WRN-MUTATION-EMPTY: declare at least one meaningful mutation");
+  }
+  const equivalent = options.equivalent ?? ((left, right) => Object.is(left, right));
+  const baseline = await options.exercise(options.baseline);
+  const killed: string[] = [];
+  const survived: string[] = [];
+  for (const mutation of options.mutations) {
+    if (!mutation.name.trim()) throw new Error("WRN-MUTATION-NAME: every mutation needs a name");
+    let same = false;
+    try {
+      same = equivalent(baseline, await options.exercise(mutation.value));
+    } catch {
+      // A behavioural failure is a killed mutation.
+    }
+    (same ? survived : killed).push(mutation.name);
+  }
+  if (survived.length) {
+    throw Object.assign(
+      new Error(`WRN-MUTATION-SURVIVED: ${survived.join(", ")}`),
+      { report: { baseline, killed, survived } },
+    );
+  }
+  return { baseline, killed, survived };
+}

packages/test/test/mutation.test.ts

@@ -0,0 +1,35 @@
+import { expect, test } from "bun:test";
+import { detectMutations } from "../src/mutation.ts";
+
+test("detectMutations reports mutations whose behaviour changes", async () => {
+  const report = await detectMutations({
+    baseline: (amount: number) => amount,
+    mutations: [
+      { name: "invert sign", value: (amount: number) => -amount },
+      { name: "drop amount", value: () => 0 },
+    ],
+    exercise: (adjust) => adjust(7),
+  });
+  expect(report.killed).toEqual(["invert sign", "drop amount"]);
+  expect(report.survived).toEqual([]);
+});
+
+test("detectMutations fails with the names of surviving mutations", async () => {
+  await expect(
+    detectMutations({
+      baseline: (amount: number) => amount,
+      mutations: [{ name: "wrong implementation", value: (amount: number) => amount }],
+      exercise: (adjust) => adjust(7),
+    }),
+  ).rejects.toThrow(/WRN-MUTATION-SURVIVED: wrong implementation/);
+});
+
+test("detectMutations accepts structured observations through an equivalence function", async () => {
+  const report = await detectMutations({
+    baseline: { status: 200 },
+    mutations: [{ name: "deny request", value: { status: 403 } }],
+    exercise: async (response) => ({ ...response, volatile: crypto.randomUUID() }),
+    equivalent: (left, right) => left.status === right.status,
+  });
+  expect(report.killed).toEqual(["deny request"]);
+});