feat: add in-memory blockstore implementation (#1)

A simple blockstore that's good for testing.

packages/interface-blockstore/package.json

@@ -17,6 +17,7 @@
     "url": "git+https://github.com/ipfs/js-ipfs-interfaces.git"
   },
   "dependencies": {
+    "err-code": "^3.0.1",
     "interface-store": "^0.0.2",
     "it-all": "^1.0.5",
     "it-drain": "^1.0.4",

packages/interface-blockstore/src/errors.js

@@ -0,0 +1,15 @@
+'use strict'
+
+const errCode = require('err-code')
+
+/**
+ * @param {Error} [err]
+ */
+function notFoundError (err) {
+  err = err || new Error('Not Found')
+  return errCode(err, 'ERR_NOT_FOUND')
+}
+
+module.exports = {
+  notFoundError
+}

packages/interface-blockstore/src/index.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const BlockstoreAdapter = require('./adapter')
+const MemoryBlockstore = require('./memory')
 
 /**
  * @typedef {import('./types').Options} Options
@@ -16,5 +17,6 @@ const BlockstoreAdapter = require('./adapter')
  */
 
 module.exports = {
-  BlockstoreAdapter
+  BlockstoreAdapter,
+  MemoryBlockstore
 }

packages/interface-blockstore/src/memory.js

@@ -0,0 +1,78 @@
+'use strict'
+
+const Adapter = require('./adapter')
+const { base32 } = require('multiformats/bases/base32')
+const raw = require('multiformats/codecs/raw')
+const { CID } = require('multiformats/cid')
+const Digest = require('multiformats/hashes/digest')
+const Errors = require('./errors')
+
+/**
+ * @typedef {import('./types').Pair} Pair
+ * @typedef {import('./types').Blockstore} Blockstore
+ * @typedef {import('interface-store').Options} Options
+ */
+
+/**
+ * @class MemoryBlockstore
+ * @implements {Blockstore}
+ */
+class MemoryBlockstore extends Adapter {
+  constructor () {
+    super()
+
+    /** @type {Record<string, Uint8Array>} */
+    this.data = {}
+  }
+
+  open () {
+    return Promise.resolve()
+  }
+
+  close () {
+    return Promise.resolve()
+  }
+
+  /**
+   * @param {CID} key
+   * @param {Uint8Array} val
+   */
+  async put (key, val) { // eslint-disable-line require-await
+    this.data[base32.encode(key.multihash.bytes)] = val
+  }
+
+  /**
+   * @param {CID} key
+   */
+  async get (key) {
+    const exists = await this.has(key)
+    if (!exists) throw Errors.notFoundError()
+    return this.data[base32.encode(key.multihash.bytes)]
+  }
+
+  /**
+   * @param {CID} key
+   */
+  async has (key) { // eslint-disable-line require-await
+    return this.data[base32.encode(key.multihash.bytes)] !== undefined
+  }
+
+  /**
+   * @param {CID} key
+   */
+  async delete (key) { // eslint-disable-line require-await
+    delete this.data[base32.encode(key.multihash.bytes)]
+  }
+
+  async * _all () {
+    yield * Object.entries(this.data)
+      .map(([key, value]) => ({ key: CID.createV1(raw.code, Digest.decode(base32.decode(key))), value }))
+  }
+
+  async * _allKeys () {
+    yield * Object.entries(this.data)
+      .map(([key]) => CID.createV1(raw.code, Digest.decode(base32.decode(key))))
+  }
+}
+
+module.exports = MemoryBlockstore