Transformation error with Ava

[spinningarrow]

I'm getting this error with some of my test files (which are written using Ava):

Transformation error
Error: [] does not match field "arguments": [Expression | SpreadElement] of type CallExpression
    at add (~/static/node_modules/ast-types/lib/types.js:580:31)
    at ~/static/node_modules/ast-types/lib/types.js:593:21
    at Array.forEach (native)
    at Function.value [as callExpression] (~/static/node_modules/ast-types/lib/types.js:592:34)
    at NodePath.ast.find.forEach.p (~/static/node_modules/jest-codemods/dist/transformers/ava.js:122:34)
    at __paths.forEach (~/static/node_modules/jscodeshift/dist/Collection.js:76:36)
    at Array.forEach (native)
    at Collection.forEach (~/static/node_modules/jscodeshift/dist/Collection.js:75:18)
    at updateAssertions (~/static/node_modules/jest-codemods/dist/transformers/ava.js:98:12)
    at transforms.forEach.t (~/static/node_modules/jest-codemods/dist/transformers/ava.js:179:29)
All done. 

How do I go about figuring out where the problem lies?

[skovhus]

Thanks for reporting this @spinningarrow .

First thing it to find the file that causes this and narrow down a minimal example of a source code that yields this error. And then either paste it here or make a PR where you add a test that documents this failure (the TDD way).

[skovhus]

@spinningarrow did you have time to come with source code that gave you this error? Would like to fix this. : )

[spinningarrow]

Hey, thanks for following up. The code I was trying it on isn't open source and I haven't found the time to come up with a minimal example yet. Will try to do it soon!

[skovhus]

@spinningarrow I'll keep this open a bit more... Would really love to get this fixed.

[spinningarrow]

Hi @skovhus, thanks for your patience. I managed to come up with a minimal example:

import test from 'ava';

const someFunction = _ => 1;

test('minimal test that throws a transformation error', t => {
  const result = someFunction();
  t.is(result);
});

The error is:

ERR test/utilities/MinimalTest.js Transformation error
Error: [] does not match field "arguments": [Expression | SpreadElement] of type CallExpression
    at add (/Users/sahil/dev/something/static/node_modules/jscodeshift/node_modules/ast-types/lib/types.js:580:31)
    at /Users/sahil/dev/something/static/node_modules/jscodeshift/node_modules/ast-types/lib/types.js:593:21
    at Array.forEach (native)
    at Function.value [as callExpression] (/Users/sahil/dev/something/static/node_modules/jscodeshift/node_modules/ast-types/lib/types.js:592:34)
    at NodePath.ast.find.forEach.p (/Users/sahil/dev/something/static/node_modules/jest-codemods/dist/transformers/ava.js:114:34)
    at __paths.forEach (/Users/sahil/dev/something/static/node_modules/jscodeshift/src/Collection.js:76:36)
    at Array.forEach (native)
    at Collection.forEach (/Users/sahil/dev/something/static/node_modules/jscodeshift/src/Collection.js:75:18)
    at updateAssertions (/Users/sahil/dev/something/static/node_modules/jest-codemods/dist/transformers/ava.js:90:12)
    at transforms.forEach.t (/Users/sahil/dev/something/static/node_modules/jest-codemods/dist/transformers/ava.js:171:29)
All done.

Looking at the Ava docs, it looks like the error is actually in the test itself - t.is takes two arguments not one, so this isn't really a bug in jest-codemods. However, the error is pretty hard to debug - is it possible to get some kind of context or line numbering when something like this happens?

[skovhus]

Thanks for digging this up! I'll have a look.

[skovhus]

Thanks @spinningarrow ! Released as 0.13.4.

https://github.com/skovhus/jest-codemods/releases/tag/0.13.4

[iansinnott]

Very helpful issue. And thanks for the fix @skovhus.

Just wanted to add for anyone else coming across this that an empty t.snapshot() will also cause the opaque transformation error listed above.

As noted, that error means there's something wrong with the ava test itself. In my case, t.snapshot() needs to be passed an argument 🤦‍♂️ , but since ava doesn't care (it will just create a snapshot containing "undefined") it's quite possible to have these sorts of issues lurking in the codebase without knowing.

[skovhus]

Thanks for sharing. Another good reason for migrating to Jest.