capsite/lib: MapStore and patterns work-alikes

Enough of @agoric/store's MapStore and @endo/patterns' M for the
credential-rotation design: makeMapStore(label, { keyShape, valueShape },
kv) keeps entries in a DO's sync KV under store:<label>:, and readOnly()
hands out the queries alone. Facets are workerd RpcTargets in place of
endo's Far.

Unlike endo, error messages never include keys or values: the values
here are credentials, and messages cross RPC into logs.

Generated-by: Claude Opus 5.5

lib/tests/store.test.ts

@@ -0,0 +1,87 @@
+import { env } from "cloudflare:workers";
+import { evictDurableObject } from "cloudflare:test";
+import { describe, expect, it } from "vitest";
+import { M, matches, mustMatch } from "../src/patterns.js";
+
+type TestEnv = { STORE_DO: DurableObjectNamespace<import("./test-worker.js").StoreHost> };
+const testEnv = env as unknown as TestEnv;
+
+const SECRET = "session=s3kr1t";
+
+/** the message an RPC call fails with, or "" if it succeeds */
+async function errorOf(call: Promise<unknown>): Promise<string> {
+	try {
+		await call;
+		return "";
+	} catch (err) {
+		return String(err);
+	}
+}
+
+describe("patterns", () => {
+	it("M.string() matches strings only; a literal matches only itself", () => {
+		expect(matches("x", M.string())).toBe(true);
+		expect(matches(1, M.string())).toBe(false);
+		expect(matches(undefined, M.any())).toBe(true);
+		expect(matches("cookie", "cookie")).toBe(true);
+		expect(matches("authorization", "cookie")).toBe(false);
+	});
+
+	it("mustMatch names the shape but not the specimen", () => {
+		expect(() => mustMatch(SECRET, "cookie", "jar: key")).toThrow('jar: key: must match "cookie"');
+		expect(() => mustMatch(SECRET, "cookie", "jar: key")).not.toThrow(SECRET);
+	});
+});
+
+describe("MapStore over RPC", () => {
+	const fresh = () => testEnv.STORE_DO.get(testEnv.STORE_DO.newUniqueId());
+
+	it("rotates: the admin's set is what the read-only view sees next", async () => {
+		const store = await fresh().cookies();
+		const rd = await store.readOnly();
+		await store.init("cookie", "session=old");
+		expect(await rd.get("cookie")).toBe("session=old");
+		await store.set("cookie", "session=new");
+		expect(await rd.entries()).toEqual([["cookie", "session=new"]]);
+	});
+
+	it("the read-only view has no write methods", async () => {
+		const store = await fresh().cookies();
+		const rd = (await store.readOnly()) as unknown as { set(k: string, v: string): Promise<void> };
+		expect(await errorOf(rd.set("cookie", SECRET))).not.toBe("");
+		expect(await store.has("cookie")).toBe(false);
+	});
+
+	it("the key shape admits only `cookie`; errors carry no values", async () => {
+		const store = await fresh().cookies();
+		const err = await errorOf(store.init("authorization", SECRET));
+		expect(err).toContain('cookie: key: must match "cookie"');
+		expect(err).not.toContain(SECRET);
+		expect(await errorOf(store.init("cookie", 42 as unknown as string))).toContain("cookie: value: must match M.string()");
+	});
+
+	it("init refuses a present key; set and get refuse a missing one", async () => {
+		const store = await fresh().cookies();
+		expect(await errorOf(store.set("cookie", SECRET))).toContain("cookie: key not found");
+		expect(await errorOf(store.get("cookie"))).toContain("cookie: key not found");
+		await store.init("cookie", SECRET);
+		const err = await errorOf(store.init("cookie", SECRET));
+		expect(err).toContain("cookie: key already registered");
+		expect(err).not.toContain(SECRET);
+	});
+
+	it("survives eviction: entries live in DO storage", async () => {
+		const stub = fresh();
+		{
+			// disposed before eviction: a live store stub holds the DO open
+			using store = await stub.cookies();
+			await store.init("cookie", "session=durable");
+		}
+		await evictDurableObject(stub);
+		using again = await stub.cookies();
+		expect(await again.get("cookie")).toBe("session=durable");
+		expect(await again.getSize()).toBe(1);
+		await again.delete("cookie");
+		expect(await again.keys()).toEqual([]);
+	});
+});

lib/tests/test-worker.ts

@@ -0,0 +1,15 @@
+/** @file the tests' main module: a DO that hosts stores on its own storage. */
+import { DurableObject } from "cloudflare:workers";
+import { M } from "../src/patterns.js";
+import { makeMapStore, type MapStore } from "../src/store.js";
+
+/** hosts the store from the credential-rotation sketch: one key, `cookie` */
+export class StoreHost extends DurableObject {
+	cookies(): MapStore<string> {
+		return makeMapStore<string>("cookie", { keyShape: "cookie", valueShape: M.string() }, this.ctx.storage.kv);
+	}
+}
+
+export default {
+	fetch: () => new Response("store tests", { status: 404 }),
+};

lib/tests/tsconfig.json

@@ -0,0 +1,7 @@
+{
+	"extends": "../tsconfig.json",
+	"compilerOptions": {
+		"types": ["@cloudflare/vitest-plugin/types"]
+	},
+	"include": ["./**/*", "../src/**/*", "../worker-configuration.d.ts"]
+}