Matrix: Ensure whole matrix is correct

[homersimpsons]

There are some proposed solutions where the mentee submit solution that would emit extra empty rows. For instance with an off by one error in a for-loop.

By checking that the whole matrix is exactly as expected we can catch such mistakes.

For the record this was discussed in the following thread; https://forum.exercism.org/t/pull-requrest-on-exercism-javascript/3440/3

Detailed summary from the thread

For instance the following solution will fail nearly all newer columns tests while it currently pass those tests:

export class Matrix {
  constructor(matrix) {
    this.matrix = matrix
  }

  get rows() {
    return this.matrix
      .split('\n')
      .map(row => row.split(' ').map(entry => +entry));
  }

  get columns() {
    const columns = [];
    for (let i = 0; i <= this.rows.length; i++) {
      columns[i] = this.rows.map((row) => {
        return row[i];
      });
     }
     return columns;
  }
}

The issue is that the user is iterating on this.rows.length instead of this.rows[0].length. And the user is using <= over <.

Those are the failing tests:

// extract column from one number matrix
expected: [[1]]
received: [[1], [undefined]]
// can extract column
expected: [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
received: [[1, 4, 7], [2, 5, 8], [3, 6, 9], [undefined, undefined, undefined]]
// extract column where numbers have different widths
expected: [[89, 18, 9], [1903, 3, 4], [3, 1, 800]]
received: [[89, 18, 9], [1903, 3, 4], [3, 1, 800], [undefined, undefined, undefined]]

Also, I do not know if this expected but the JS test suite has one more test:

https://github.com/homersimpsons/javascript/blob/f9f722fc7c4b6ab3d700178f076e305784ba686b/exercises/practice/matrix/matrix.spec.js#L34-L36

NB: A Pull Request is already opened on the exercism/javascript repository: https://github.com/exercism/javascript/pull/2065/files

[github-actions]

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[homersimpsons]

For the record I did update the code with the reimplements and comments keys homersimpsons@9c22e01.

[SleeplessByte]

@homersimpsons I cannot reopen this because the branch was force pushed. If you recreate the PR and then tag me, I'll open it.