AVA unit tests fails passed Javascript test specs

I am currently working with ES6 modules with .mjs extensions and creating test cases for some functions.

I have chosen AVA due to its support of this extension type but the test executions are not running as expected.

I assume the script is not being transformed properly or I am missing a configuration in my package.json

I appreciate any help at all from anyone with experience with using AVA with --experimental-modules

package.json

{
    "scripts": {
        "test": "ava --init"
    },
    "ava": {
        "require": [
      "esm"
    ],
        "babel": false,
        "extensions": [
      "mjs"
    ]
    }
}

test.spec.mjs

import rotate from './index.mjs'
import test from 'ava';

test('rotate img', t => {
    var m = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
    rotate(m);

    t.is(m, [[7, 4, 1], [8, 5, 2], [9, 6, 3]]);
});

index.js

 var rotate =function(matrix) {
    let cols = 0,
     original = JSON.parse(JSON.stringify(matrix));

    for (let i=0; i < matrix.length; i++){
        for (let j = matrix.length; j > 0; j--){
            matrix[i][cols]=original[j-1][i]; 

            cols+=1;
            if(cols == matrix.length){
                cols= 0;
            }
        }
    }
}
export default rotate;

On running npm test as defined in package script

ERROR:

 1 test failed

  rotate

   12: rotate(m);
   13:     t.is(m, [[7,4,1],[8,5,2],[9,6,3]
   14: ]);

  Values are deeply equal to each other, but they are not the same:

  [[7,4,1,],[8,5,2,],[9,6,3,],] <<fails

npm ERR! Test failed.  See above for more details.

AVA does not support .mjs out of the box, but it looks like you figured out the configuration.

For the test script, just use ava, without the --init.

All that said, the test is failing because you're using the wrong assertion. t.is(actual, expected) uses Object.is(actual, expected) (which is pretty much actual === expected). And you can't compare arrays like that.

Use t.deepEqual() instead.