pify for gm doesn't seems to be working

[kdybicz]

Hi,

I'm trying to fix AVA tests for some functionality and I need to Promisify gm(...).size() function. Unfortunately I'm not able to do that properly:

const out = await pify(gm(image.data).size());
console.log("gm output: " + out.width);
---
  gm output: undefined

const out = await pify(gm(image.data).size)();
console.log("gm output: " + out.width);
---
  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: Cannot read property 'size' of undefined
    proto.(anonymous function) (node_modules/gm/lib/getters.js:47:20)
    node_modules/pify/index.js:29:7
    node_modules/pify/index.js:12:10
    ret (node_modules/pify/index.js:56:34)
    Test.<anonymous> (test/resize-jpeg.js:37:20)
    Generator.next (<anonymous>)

const out = await pify(gm(image.data).size.bind(gm))();
console.log("gm output: " + out.width);
---
  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: Cannot read property 'size' of undefined
    proto.(anonymous function) (node_modules/gm/lib/getters.js:47:20)
    node_modules/pify/index.js:29:7
    node_modules/pify/index.js:12:10
    ret (node_modules/pify/index.js:56:34)
    Test.<anonymous> (test/resize-jpeg.js:37:20)
    Generator.next (<anonymous>)

const out = await pify(gm(image.data)).size();
console.log("gm output: " + out.width);
---
  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: pify(...).size is not a function
    Test.<anonymous> (test/resize-jpeg.js:37:43)
    Generator.next (<anonymous>)

So, my question is: if it's possible to pify gm and if so, I would like to know how?

[SamVerschueren]

Try this

const image = gm(…);

pify(image.bind(image));

[kdybicz]

Doesn't work:

  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: image.bind is not a function
    Test.<anonymous> (test/resize-jpeg.js:39:32)
    Generator.next (<anonymous>)

neither does Example 3.

[SamVerschueren]

Oh yes off course. You have to pify pity the write function, not the others.

const image = gm(…).size(100, 100);

pify(image.write.bind(image))().then(...);

[schnittstabil]

Your first and your second outputs show, that gm(image.data) returns undefined:

const out = await pify(gm(image.data).size)();
const out = await pify(gm(image.data).size.bind(gm))();
---
  Error: Cannot read property 'size' of undefined

At least these issues seem to be unrelated to pify.

Aww, sorry, #16 seems related to your issue.

---

About your third example:

const out = await pify(gm(image.data)).size();
---
  Error: pify(...).size is not a function

I cannot guess what size is: a number or a string or …? – @kdybicz Do you mind investigating the type and value of size?

[kdybicz]

size is a function http://aheckmann.github.io/gm/docs.html#getters

gm(image.data) returns undefined

This one occures only when using pify().

console.log("Plain gm: " + gm(image.data));
console.log("Type of gm.size: " + typeof gm(image.data).size);
const out = await pify(gm(image.data).size)();
---
Plain gm: [object Object]
Type of gm.size: function

  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: Cannot read property 'size' of undefined
    proto.(anonymous function) (node_modules/gm/lib/getters.js:47:20)
    node_modules/pify/index.js:29:7
    node_modules/pify/index.js:12:10
    ret (node_modules/pify/index.js:56:34)
    Test.<anonymous> (test/resize-jpeg.js:40:20)
    Generator.next (<anonymous>)

---

Edit: yeah, I was afraid that this could be related to #16

[schnittstabil]

Maybe you want to try this:

const img = gm(image.data);
const out = await pify(img.size.bind(img))(); // <-- bind to img, not to gm!

If it works you may want to try bind-methods auto-bind as long as #16 isn't solved:

// untested(!)
const autoBind = require('auto-bind');
const gm = require("gm").subClass({ imageMagick: true });
const gmP = (...args) => pify(autoBind(gm(...args)));

test("Resize JPEG with jpegoptim", async t => {
    // …
    const out = await gmP(destPath).size();
    t.is(out.width, 200);
});

[kdybicz]

Unfortunately this doesn't seems to be working, I'm getting:

  1 failed

  resize-jpeg › Resize JPEG with jpegoptim
  Error: Cannot convert undefined or null to object
    Function.keys (<anonymous>)
    module.exports (node_modules/pify/index.js:59:16)
    gmP (test/resize-jpeg.js:11:26)
    Test.<anonymous> (test/resize-jpeg.js:39:20)
    Generator.next (<anonymous>)

[schnittstabil]

const img = gm(image.data);
const out = await pify(img.size.bind(img))(); // <-- bind to img, not to gm!

@kdybicz Above works as expected.

As a #16 workaround, I suggest a small helper function:

const bind = obj => {
    for (const key in obj) {
        const val = obj[key];

        if (typeof val === 'function') {
            obj[key] = val.bind(obj);
        }
    }

    return obj;
};

const gmP = (...args) => pify(bind(gm(...args)));

By the way, your tests have additional issues (see https://github.com/secretescapes/aws-lambda-image/pull/1):

• async/await and callback style are unfortunately mixed; thus your assertions are not executed (https://github.com/schnittstabil/aws-lambda-image/commit/b6c14dc713f084ef788229a9af73962e268abb3b reveals that)
• cleanup is done with within the test functions (https://github.com/schnittstabil/aws-lambda-image/commit/f1cd0a0c863e5ab92d3b32a8ee88e704a8a5e16c shows a better alternative)

[schnittstabil]

I'm closing this, because it is a #16 duplicate.

[kdybicz]

This is my approach to solving this issue https://github.com/ysugimoto/aws-lambda-image/pull/87/files but I will for sure take a look at your proposal. Thanks!

[schnittstabil]

Btw, bind-all provides the same functionality as my bind helper above:

const bindAll = require('bind-all');

const gmP = (...args) => pify(bindAll(gm(...args)));

test("Resize JPEG with cjpeg", async t => {
    //…
    const out = await gmP(destPath).size();
    t.is(out.width, 200);
});

[kdybicz]

Thanks to your advice I did end up with code, that is working perfectly fine! https://github.com/secretescapes/aws-lambda-image/blob/improving-tests-quality-v2/test/resize-jpeg.js