test: tighten secure random coverage

src/infra/secure-random.test.ts

@@ -1,20 +1,43 @@
-import { describe, expect, it } from "vitest";
+import { Buffer } from "node:buffer";
+import { describe, expect, it, vi } from "vitest";
+
+const cryptoMocks = vi.hoisted(() => ({
+  randomBytes: vi.fn((bytes: number) => Buffer.alloc(bytes, 0xab)),
+  randomUUID: vi.fn(),
+}));
+
+vi.mock("node:crypto", () => ({
+  randomBytes: cryptoMocks.randomBytes,
+  randomUUID: cryptoMocks.randomUUID,
+}));
+
 import { generateSecureToken, generateSecureUuid } from "./secure-random.js";
 
 describe("secure-random", () => {
-  it("generates UUIDs", () => {
-    const first = generateSecureUuid();
-    const second = generateSecureUuid();
-    expect(first).not.toBe(second);
-    expect(first).toMatch(
-      /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i,
-    );
+  it("delegates UUID generation to crypto.randomUUID", () => {
+    cryptoMocks.randomUUID.mockReturnValueOnce("uuid-1").mockReturnValueOnce("uuid-2");
+
+    expect(generateSecureUuid()).toBe("uuid-1");
+    expect(generateSecureUuid()).toBe("uuid-2");
+    expect(cryptoMocks.randomUUID).toHaveBeenCalledTimes(2);
   });
 
-  it("generates url-safe tokens", () => {
+  it("generates url-safe tokens with the default byte count", () => {
+    cryptoMocks.randomBytes.mockClear();
+
     const defaultToken = generateSecureToken();
-    const token18 = generateSecureToken(18);
+
+    expect(cryptoMocks.randomBytes).toHaveBeenCalledWith(16);
     expect(defaultToken).toMatch(/^[A-Za-z0-9_-]+$/);
-    expect(token18).toMatch(/^[A-Za-z0-9_-]{24}$/);
+    expect(defaultToken).toHaveLength(Buffer.alloc(16, 0xab).toString("base64url").length);
+  });
+
+  it("passes custom byte counts through to crypto.randomBytes", () => {
+    cryptoMocks.randomBytes.mockClear();
+
+    const token18 = generateSecureToken(18);
+
+    expect(cryptoMocks.randomBytes).toHaveBeenCalledWith(18);
+    expect(token18).toBe(Buffer.alloc(18, 0xab).toString("base64url"));
   });
 });