fix: synchronize mounted component props

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"]);
+});