fix: async/await improvements

Address comments on [parent PR](#37)

Author: dirkmc

README.md

@@ -89,8 +89,8 @@ const mh = await multihashing(buf, 'sha1')
 const digest = await multihashing.digest(buf, 'sha1')
 
 // Use `.createHash(...)` for the raw hash functions
-const h = multihashing.createHash('sha1')
-const digest = await h(buf)
+const hash = multihashing.createHash('sha1')
+const digest = await hash(buf)
 ```
 
 ## Examples

package.json

@@ -20,6 +20,10 @@
   "browser": {
     "./src/sha.js": "./src/sha.browser.js"
   },
+  "pre-push": [
+    "lint",
+    "test"
+  ],
   "scripts": {
     "test": "aegir test",
     "test:browser": "aegir test -t browser",
@@ -37,9 +41,11 @@
   "repository": "github:multiformats/js-multihashing-async",
   "dependencies": {
     "blakejs": "^1.1.0",
+    "err-code": "^1.1.2",
     "js-sha3": "~0.8.0",
     "multihashes": "~0.4.13",
-    "murmurhash3js-revisited": "^3.0.0"
+    "murmurhash3js-revisited": "^3.0.0",
+    "sinon": "^7.2.7"
   },
   "devDependencies": {
     "aegir": "^18.0.3",

src/blake.js

@@ -17,16 +17,13 @@ const blake2s = {
   digest: blake.blake2sFinal
 }
 
-const makeB2Hash = (size, hf) => (data) => {
-  return new Promise((resolve, reject) => {
-    try {
-      const ctx = hf.init(size, null)
-      hf.update(ctx, data)
-      resolve(Buffer.from(hf.digest(ctx)))
-    } catch (error) {
-      reject(error)
-    }
-  })
+// Note that although this function doesn't do any asynchronous work, we mark
+// the function as async because it must return a Promise to match the API
+// for other functions that do perform asynchronous work (see sha.browser.js)
+const makeB2Hash = (size, hf) => async (data) => {
+  const ctx = hf.init(size, null)
+  hf.update(ctx, data)
+  return Buffer.from(hf.digest(ctx))
 }
 
 module.exports = (table) => {

src/crypto.js

@@ -5,42 +5,39 @@ const mur = require('murmurhash3js-revisited')
 const sha = require('./sha')
 const { fromNumberTo32BitBuf } = require('./utils')
 
-const hash = (algorithm) => (data) => {
-  return new Promise((resolve, reject) => {
-    try {
-      switch (algorithm) {
-        case 'sha3-224':
-          return resolve(Buffer.from(sha3.sha3_224.arrayBuffer(data)))
-        case 'sha3-256':
-          return resolve(Buffer.from(sha3.sha3_256.arrayBuffer(data)))
-        case 'sha3-384':
-          return resolve(Buffer.from(sha3.sha3_384.arrayBuffer(data)))
-        case 'sha3-512':
-          return resolve(Buffer.from(sha3.sha3_512.arrayBuffer(data)))
-        case 'shake-128':
-          return resolve(Buffer.from(sha3.shake128.create(128).update(data).arrayBuffer()))
-        case 'shake-256':
-          return resolve(Buffer.from(sha3.shake256.create(256).update(data).arrayBuffer()))
-        case 'keccak-224':
-          return resolve(Buffer.from(sha3.keccak224.arrayBuffer(data)))
-        case 'keccak-256':
-          return resolve(Buffer.from(sha3.keccak256.arrayBuffer(data)))
-        case 'keccak-384':
-          return resolve(Buffer.from(sha3.keccak384.arrayBuffer(data)))
-        case 'keccak-512':
-          return resolve(Buffer.from(sha3.keccak512.arrayBuffer(data)))
-        case 'murmur3-128':
-          return resolve(Buffer.from(mur.x64.hash128(data), 'hex'))
-        case 'murmur3-32':
-          return resolve(fromNumberTo32BitBuf(mur.x86.hash32(data)))
+// Note that although this function doesn't do any asynchronous work, we mark
+// the function as async because it must return a Promise to match the API
+// for other functions that do perform asynchronous work (see sha.browser.js)
+const hash = (algorithm) => async (data) => {
+  switch (algorithm) {
+    case 'sha3-224':
+      return Buffer.from(sha3.sha3_224.arrayBuffer(data))
+    case 'sha3-256':
+      return Buffer.from(sha3.sha3_256.arrayBuffer(data))
+    case 'sha3-384':
+      return Buffer.from(sha3.sha3_384.arrayBuffer(data))
+    case 'sha3-512':
+      return Buffer.from(sha3.sha3_512.arrayBuffer(data))
+    case 'shake-128':
+      return Buffer.from(sha3.shake128.create(128).update(data).arrayBuffer())
+    case 'shake-256':
+      return Buffer.from(sha3.shake256.create(256).update(data).arrayBuffer())
+    case 'keccak-224':
+      return Buffer.from(sha3.keccak224.arrayBuffer(data))
+    case 'keccak-256':
+      return Buffer.from(sha3.keccak256.arrayBuffer(data))
+    case 'keccak-384':
+      return Buffer.from(sha3.keccak384.arrayBuffer(data))
+    case 'keccak-512':
+      return Buffer.from(sha3.keccak512.arrayBuffer(data))
+    case 'murmur3-128':
+      return Buffer.from(mur.x64.hash128(data), 'hex')
+    case 'murmur3-32':
+      return fromNumberTo32BitBuf(mur.x86.hash32(data))
 
-        default:
-          throw new TypeError(`${algorithm} is not a supported algorithm`)
-      }
-    } catch (error) {
-      return reject(error)
-    }
-  })
+    default:
+      throw new TypeError(`${algorithm} is not a supported algorithm`)
+  }
 }
 
 module.exports = {

src/index.js

@@ -1,19 +1,19 @@
 'use strict'
 
+const errcode = require('err-code')
 const multihash = require('multihashes')
 const crypto = require('./crypto')
 
 /**
- * Hash the given `buf` using the algorithm specified
- * by `func`.
+ * Hash the given `buf` using the algorithm specified by `alg`.
  * @param {Buffer} buf - The value to hash.
- * @param {number|string} func - The algorithm to use.
+ * @param {number|string} alg - The algorithm to use eg 'sha1'
  * @param {number} [length] - Optionally trim the result to this length.
  * @returns {Promise<Buffer>}
  */
-function Multihashing (buf, func, length) {
-  return Multihashing.digest(buf, func, length)
-    .then(digest => multihash.encode(digest, func, length))
+async function Multihashing (buf, alg, length) {
+  const digest = await Multihashing.digest(buf, alg, length)
+  return multihash.encode(digest, alg, length)
 }
 
 /**
@@ -30,38 +30,34 @@ Multihashing.multihash = multihash
 
 /**
  * @param {Buffer} buf - The value to hash.
- * @param {number|string} func - The algorithm to use.
+ * @param {number|string} alg - The algorithm to use eg 'sha1'
  * @param {number} [length] - Optionally trim the result to this length.
- * @returns {Promise}
+ * @returns {Promise<Buffer>}
  */
-Multihashing.digest = (buf, func, length) => {
-  try {
-    return Multihashing.createHash(func)(buf)
-      .then(digest => {
-        if (length) {
-          return digest.slice(0, length)
-        }
-        return digest
-      })
-  } catch (err) {
-    return Promise.reject(err)
-  }
+Multihashing.digest = async (buf, alg, length) => {
+  const hash = Multihashing.createHash(alg)
+  const digest = await hash(buf)
+  return length ? digest.slice(0, length) : digest
 }
 
 /**
- * Creates a function that hashs with the provided algorithm
+ * Creates a function that hashes with the given algorithm
  *
- * @param {string|number} func
+ * @param {string|number} alg - The algorithm to use eg 'sha1'
  *
- * @returns {function} - The to `func` corresponding hash function.
+ * @returns {function} - The hash function corresponding to `alg`
  */
-Multihashing.createHash = function (func) {
-  func = multihash.coerceCode(func)
-  if (!Multihashing.functions[func]) {
-    throw new Error('multihash function ' + func + ' not yet supported')
+Multihashing.createHash = function (alg) {
+  if (!alg) {
+    throw errcode('hash algorithm must be specified', 'ERR_HASH_ALGORITHM_NOT_SPECIFIED')
+  }
+
+  alg = multihash.coerceCode(alg)
+  if (!Multihashing.functions[alg]) {
+    throw errcode(`multihash function '${alg}' not yet supported`, 'ERR_HASH_ALGORITHM_NOT_SUPPORTED')
   }
 
-  return Multihashing.functions[func]
+  return Multihashing.functions[alg]
 }
 
 /**

src/sha.browser.js

@@ -8,18 +8,17 @@ module.exports = (algorithm) => {
     )
   }
 
-  return (data) => {
+  return async (data) => {
     switch (algorithm) {
       case 'sha1':
-        return crypto.subtle.digest({ name: 'SHA-1' }, data).then(Buffer.from)
+        return Buffer.from(await crypto.subtle.digest({ name: 'SHA-1' }, data))
       case 'sha2-256':
-        return crypto.subtle.digest({ name: 'SHA-256' }, data).then(Buffer.from)
+        return Buffer.from(await crypto.subtle.digest({ name: 'SHA-256' }, data))
       case 'sha2-512':
-        return crypto.subtle.digest({ name: 'SHA-512' }, data).then(Buffer.from)
+        return Buffer.from(await crypto.subtle.digest({ name: 'SHA-512' }, data))
       case 'dbl-sha2-256': {
-        return crypto.subtle.digest({ name: 'SHA-256' }, data)
-          .then(d => crypto.subtle.digest({ name: 'SHA-256' }, d))
-          .then(Buffer.from)
+        const d = await crypto.subtle.digest({ name: 'SHA-256' }, data)
+        return Buffer.from(await crypto.subtle.digest({ name: 'SHA-256' }, d))
       }
       default:
         throw new TypeError(`${algorithm} is not a supported algorithm`)

src/sha.js

@@ -1,25 +1,22 @@
 'use strict'
 const crypto = require('crypto')
 
-module.exports = (algorithm) => (data) => {
-  return new Promise((resolve, reject) => {
-    try {
-      switch (algorithm) {
-        case 'sha1':
-          return resolve(crypto.createHash('sha1').update(data).digest())
-        case 'sha2-256':
-          return resolve(crypto.createHash('sha256').update(data).digest())
-        case 'sha2-512':
-          return resolve(crypto.createHash('sha512').update(data).digest())
-        case 'dbl-sha2-256': {
-          const first = crypto.createHash('sha256').update(data).digest()
-          return resolve(crypto.createHash('sha256').update(first).digest())
-        }
-        default:
-          throw new TypeError(`${algorithm} is not a supported algorithm`)
-      }
-    } catch (error) {
-      return reject(error)
+// Note that although this function doesn't do any asynchronous work, we mark
+// the function as async because it must return a Promise to match the API
+// for other functions that do perform asynchronous work (see sha.browser.js)
+module.exports = (algorithm) => async (data) => {
+  switch (algorithm) {
+    case 'sha1':
+      return crypto.createHash('sha1').update(data).digest()
+    case 'sha2-256':
+      return crypto.createHash('sha256').update(data).digest()
+    case 'sha2-512':
+      return crypto.createHash('sha512').update(data).digest()
+    case 'dbl-sha2-256': {
+      const first = crypto.createHash('sha256').update(data).digest()
+      return crypto.createHash('sha256').update(first).digest()
     }
-  })
+    default:
+      throw new TypeError(`${algorithm} is not a supported algorithm`)
+  }
 }

test/index.spec.js

@@ -5,12 +5,13 @@ const chai = require('chai')
 const dirtyChai = require('dirty-chai')
 chai.use(dirtyChai)
 const expect = chai.expect
+const sinon = require('sinon')
 
 const multihashing = require('../src')
 const fixtures = require('./fixtures/encodes')
 
 describe('multihashing', () => {
-  fixtures.forEach((fixture) => {
+  for (const fixture of fixtures) {
     const raw = fixture[0]
     const func = fixture[1]
     const encoded = fixture[2]
@@ -19,7 +20,7 @@ describe('multihashing', () => {
       const digest = await multihashing(Buffer.from(raw), func)
       expect(digest.toString('hex')).to.eql(encoded)
     })
-  })
+  }
 
   it('cuts the length', async () => {
     const buf = Buffer.from('beep boop')
@@ -40,3 +41,44 @@ describe('multihashing', () => {
     )
   })
 })
+
+describe('error handling', () => {
+  const methods = {
+    multihashing: multihashing,
+    digest: multihashing.digest,
+    createHash: (buff, alg) => multihashing.createHash(alg)
+  }
+
+  for (const [name, fn] of Object.entries(methods)) {
+    describe(name, () => {
+      it('throws an error when there is no hashing algorithm specified', async () => {
+        const buf = Buffer.from('beep boop')
+
+        try {
+          await fn(buf)
+        } catch (err) {
+          expect(err).to.exist()
+          expect(err.code).to.eql('ERR_HASH_ALGORITHM_NOT_SPECIFIED')
+          return
+        }
+        expect.fail('Did not throw')
+      })
+
+      it('throws an error when the hashing algorithm is not supported', async () => {
+        const buf = Buffer.from('beep boop')
+
+        const stub = sinon.stub(require('multihashes'), 'coerceCode').returns('snake-oil')
+        try {
+          await fn(buf, 'snake-oil')
+        } catch (err) {
+          expect(err).to.exist()
+          expect(err.code).to.eql('ERR_HASH_ALGORITHM_NOT_SUPPORTED')
+          return
+        } finally {
+          stub.restore()
+        }
+        expect.fail('Did not throw')
+      })
+    })
+  }
+})