feat: vendor permission system source

pi-permission-system/test/json-safe-stringify.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, test } from "vitest";
+import { safeJsonStringify } from "#src/json-safe-stringify";
+
+describe("safeJsonStringify", () => {
+  test("serializes a plain record", () => {
+    expect(safeJsonStringify({ toolName: "write", allowed: true })).toBe(
+      '{"toolName":"write","allowed":true}',
+    );
+  });
+
+  test("returns undefined for a value JSON cannot represent", () => {
+    expect(safeJsonStringify(undefined)).toBe(undefined);
+    expect(safeJsonStringify(() => "noop")).toBe(undefined);
+  });
+
+  describe("Error values", () => {
+    test("expands an Error into name, message, and stack", () => {
+      const error = new Error("boom");
+      error.stack = "Error: boom\n    at somewhere";
+
+      expect(safeJsonStringify({ error })).toBe(
+        '{"error":{"name":"Error","message":"boom","stack":"Error: boom\\n    at somewhere"}}',
+      );
+    });
+
+    test("expands an Error at the root", () => {
+      const error = new TypeError("bad type");
+      error.stack = "trace";
+
+      expect(safeJsonStringify(error)).toBe(
+        '{"name":"TypeError","message":"bad type","stack":"trace"}',
+      );
+    });
+  });
+
+  describe("bigint values", () => {
+    test("stringifies a bigint rather than throwing", () => {
+      expect(safeJsonStringify({ size: 9007199254740993n })).toBe(
+        '{"size":"9007199254740993"}',
+      );
+    });
+  });
+
+  describe("circular references", () => {
+    test("replaces a self-reference with the [Circular] marker", () => {
+      const node: Record<string, unknown> = { name: "root" };
+      node.self = node;
+
+      expect(safeJsonStringify(node)).toBe(
+        '{"name":"root","self":"[Circular]"}',
+      );
+    });
+
+    test("replaces a mutual reference cycle with the [Circular] marker", () => {
+      const parent: Record<string, unknown> = { kind: "parent" };
+      const child: Record<string, unknown> = { kind: "child", parent };
+      parent.child = child;
+
+      expect(safeJsonStringify(parent)).toBe(
+        '{"kind":"parent","child":{"kind":"child","parent":"[Circular]"}}',
+      );
+    });
+
+    test("also marks a repeated non-cyclic reference, since seen entries are never released", () => {
+      const shared = { id: 1 };
+
+      expect(safeJsonStringify({ first: shared, second: shared })).toBe(
+        '{"first":{"id":1},"second":"[Circular]"}',
+      );
+    });
+  });
+});