What would be a good method for testing over 100,000 cases in Jest?

Question

I use a cartesian combination method to generate combos of test cases from an array.

const cartesian = (...a) => a.reduce((a, b) => a.flatMap(d => b.map(e => [d, e].flat())));

Found in this answer.

let arrayOne = [0, 1];
let arrayTwo = [0, 1];

const result = cartesian(arrayOne, arrayTwo)

console.log(result)

/**
* Result should equal:
* [
* [0, 1],
* [1, 0],
* [1, 1],
* [0, 0] 
* ]
*/

That part is working nicely.

I then take the array of arrays generated from this method and pass them to Jest's .each method on the test.

describe('test', () => {
  test.each(cases)('when one equals %s and two equals %s', (one, two) => {
    // my test logic
  })
})

This also works nicely. However, when I have a very large number of combinations I want to test,

e.g., [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 ...]

that's when things get tricky.

I don't think JavaScript is built to handle that level of computational complexity. I usually get a heap out of memory when I run through so many cases in a single test.

This is a shame, because this method is quite convenient for automating test case building, and I really would like to expand it to other languages (like PHP and Python), but I think I'll have the same problem once my test cases pass the 100,000 mark.

One method I've tried is limiting the number of test cases to an arbitrary number.

describe('test', () => {
  test.each(cases.slice(0,5000))('when one equals %s and two equals %s', (one, two) => {
    // my test logic
  })
})

This lets me run them without a problem, but I can't see all the cases without manually commenting out values in the arrays I've already tested.

const arrayOne = [
  // 0
  1
  ...
]

Doing that every time doesn't seem right.

Is there some way of making the test:

Go through 50,000 records
Save their results
Clear the memory
Start again from the latest index

I think that might be how it's done.

Find a reasonable subset of inputs and outputs. I don’t think you need to test every combination — Daniel A. White, Feb 28 '23 at 01:45
Seems like you are brute forcing with Jest which is already a heavy test framework. What's your exact use case behind doing such operations? — Fcmam5, Feb 28 '23 at 14:33
@Fcmam5 I just discovered the possibility of looping repetitive tests. I was simply exploring the limits. — Daniel Haven, Mar 01 '23 at 18:18

score 0 · Answer 1 · answered Feb 28 '23 at 15:32

Why not simple loop through the tests one by one? The test is Typescript/JavaScript, so do your testing in a loop.

describe('test', () => {
    for await (const case of cases) { // Doing the await in case you need async
        test('should ...', () => {
           // my test logic
        });
    }
});

What would be a good method for testing over 100,000 cases in Jest?

1 Answers1