fix: handle Buffer serialization (#277)

Buffer has a toJSON implementation which is called before our replacer
function when serialising. It's JSON form is an object like `{ type:
'Buffer, data: number[] }`.

This means it doesn't get identfied as $bytes, and does not get
deserialised in the reviver. I think we'd rather have `Uint8Array`
everywhere so this PR fixes it so that it gets revived as that.

License: MIT
Signed-off-by: Oli Evans <oli@protocol.ai>

packages/access-client/package.json

@@ -85,7 +85,7 @@
     "@types/assert": "^1.5.6",
     "@types/inquirer": "^9.0.3",
     "@types/mocha": "^10.0.1",
-    "@types/node": "^18.11.9",
+    "@types/node": "^18.11.10",
     "@types/ws": "^8.5.3",
     "@ucanto/server": "^4.0.2",
     "assert": "^2.0.0",

packages/access-client/src/utils/json.js

@@ -11,6 +11,8 @@ export const replacer = (k, v) => {
     return { $map: [...v.entries()] }
   } else if (v instanceof Uint8Array) {
     return { $bytes: [...v.values()] }
+  } else if (v?.type === 'Buffer' && Array.isArray(v.data)) {
+    return { $bytes: v.data }
   }
   return v
 }

packages/access-client/test/drivers/conf.node.test.js

@@ -1,4 +1,5 @@
 import assert from 'assert'
+import { Buffer } from 'node:buffer'
 import { ConfDriver } from '../../src/drivers/conf.js'
 
 describe('Conf driver', () => {
@@ -11,4 +12,13 @@ describe('Conf driver', () => {
     assert.strictEqual(data.foo, undefined)
     assert.strictEqual(data.bar, 1)
   })
+
+  it('should store a Buffer', async () => {
+    const driver = new ConfDriver({ profile: 'w3protocol-access-client-test' })
+    await driver.reset()
+    await driver.save({ buf: Buffer.from('⁂', 'utf8') })
+    const actual = await driver.load()
+    assert(actual)
+    assert.deepEqual(actual.buf, new TextEncoder().encode('⁂'))
+  })
 })