Throw exception when using `equal` & `same` for some variable

[huan]

Versions

tap@15.0.10
wechaty@1.9.8
wechaty-puppet-mock@1.9.1

equal() Cannot read property 'length' of null

# Subtest: Wechaty <> Tap `Error: undefined is not a function`
    not ok 1 - Cannot read property 'length' of null
      ---
      stack: |
        Format.arrayIsEmpty (node_modules/tcompare/lib/format.js:390:31)
        Format.array (node_modules/tcompare/lib/format.js:384:14)
        Format.collection (node_modules/tcompare/lib/format.js:211:58)
        Format.printValue (node_modules/tcompare/lib/format.js:140:21)
        Format.print (node_modules/tcompare/lib/format.js:78:51)
        Same.simplePrint (node_modules/tcompare/lib/same.js:134:8)
        Same.diff (node_modules/tcompare/lib/same.js:434:35)
        Same.print (node_modules/tcompare/lib/same.js:146:37)
        simple (node_modules/tcompare/index.js:9:11)
        node_modules/tcompare/index.js:13:3
      at:
        line: 390
        column: 31
        file: node_modules/tcompare/lib/format.js
        function: Format.arrayIsEmpty
      type: TypeError
      tapCaught: returnedPromiseRejection
      test: "Wechaty <> Tap `Error: undefined is not a function`"
      source: |2
          arrayIsEmpty () {
            return this.objectAsArray.length === 0
        ------------------------------^
          }
          arrayEmpty () {
      ...
    
    1..1
    # failed 1 test

same() Error: undefined is not a function

$ ./src/t.ts 
TAP version 13
# Subtest: Wechaty <> Tap
    not ok 1 - undefined is not a function
      ---
      stack: >
        Object.createSeq [as createNode]
        (node_modules/yaml/dist/Schema-88e323a7.js:35:16)
      
        createNode (node_modules/yaml/dist/Schema-88e323a7.js:444:41)
      
        Schema.createNode (node_modules/yaml/dist/Schema-88e323a7.js:507:12)
      
        Schema.createPair (node_modules/yaml/dist/Schema-88e323a7.js:515:20)
      
        Object.createMap [as createNode] (node_modules/yaml/dist/Schema-88e323a7.js:13:63)
      
        createNode (node_modules/yaml/dist/Schema-88e323a7.js:444:41)
      
        Schema.createNode (node_modules/yaml/dist/Schema-88e323a7.js:507:12)
      
        Schema.createPair (node_modules/yaml/dist/Schema-88e323a7.js:515:20)
      
        Object.createMap [as createNode] (node_modules/yaml/dist/Schema-88e323a7.js:13:63)
      
        createNode (node_modules/yaml/dist/Schema-88e323a7.js:444:41)
      at:
        line: 35
        column: 16
        file: node_modules/yaml/dist/Schema-88e323a7.js
        function: Object.createSeq
        method: createNode
      type: TypeError
      tapCaught: returnedPromiseRejection
      test: Wechaty <> Tap
      source: |2
          if (obj && obj[Symbol.iterator]) {
            for (const it of obj) {
        ---------------^
              const v = schema.createNode(it, ctx.wrapScalars, null, ctx);
              seq.items.push(v);
      ...
    
    1..2
    # test count(1) != plan(2)
    # failed 1 test
not ok 1 - Wechaty <> Tap # time=42.396ms

1..1
# failed 1 test
# time=54.162ms

Reproduciable minimum code

NPM Versions:

npm install tap@15.0.10 wechaty@1.9.8 wechaty-puppet-mock@1.9.1

Code:

#!/usr/bin/env -S node --no-warnings --loader ts-node/esm

import { test } from 'tap'  // tap@15.0.10

import { WechatyBuilder } from 'wechaty'  // wechaty@1.9.8
import { PuppetMock }     from 'wechaty-puppet-mock'  // wechaty-puppet-mock@1.9.1

test('Wechaty <> Tap reproduce bug', async t => {
  const puppet = new PuppetMock()
  const wechaty = WechatyBuilder.build({ puppet })

  t.same(wechaty, undefined, 'should have wechaty registered after use plugin')
  /**
   * Error: Cannot read property 'length' of null
   *
   * stack: |
   *    Format.arrayIsEmpty (node_modules/tcompare/lib/format.js:390:31)
   */

  t.equal(wechaty, undefined, 'should have wechaty registered after use plugin')
  /**
   * Error: undefined is not a function
   *
   * stack: >
   *    Object.createSeq [as createNode]
   *    (node_modules/yaml/dist/Schema-88e323a7.js:35:16)
   */
}).catch(console.error)

Cross-posted from:

• Tap error: undefined is not a function & Cannot read property 'length' of null wechaty/wechaty#2304

[isaacs]

It's a bug in the MemoryCard module. huan/memory-card#39

The presence of this function tells tap that it's an array-like, but then the iterator function returns an invalid response, so Array.from() fails.

Nevertheless, tcompare should handle this case more gracefully. Leaving open, but I guess the solution here is to catch the error from Array.from(), and then if it does throw, mark the object as not array-like, no matter what it looks like, and back up and re-try the formatting operation with that new info.

[isaacs]

Even more minimal example:

const t = require('tap')
t.test('same', async t => {
  t.same({ [Symbol.iterator] () { return {} } }, undefined)
})
t.test('equal', async t => {
  t.equal({ [Symbol.iterator] () { return {} } }, undefined)
})

[huan]

@isaacs Thank you very much for pointing the problem out!

I believe I have fixed the iterator problem in the MemoryCard (this commit) by removing the [Symbol.iterator]() entrance and it should compatible with the current version of the Tap.

And I totally agree that the Tap should validate the [Symbol.iterator]() and ignore it if it does not follow the array convention.

BTW: could you also take a look at the below issue? I believe it's a blocker for ESM module developers/users when they need to publish binary commands under the Windows platform:

• [FEATURE] drop env's -S flag npm/cmd-shim#54

Thank you very much!

[isaacs]

Anyone encountering this can fix it with npm update tcompare, or reinstall tap.