Jest Sorted

Inspired by chai sorted and jest-extended. This packages extends jest.expect with 2 custom matchers, toBeSorted and toBeSortedBy

Examples

expect([1, 2, 3]).toBeSorted();
expect([3, 2, 1]).toBeSorted({ descending: true });

expect([{ id: 1 }, { id: 2 }, { id: 3 }]).toBeSortedBy('id');
expect([{ count: '10' }, { count: '5' }]).toBeSortedBy('count', {
  descending: true,
  coerce: true,
});

Installation

With npm:

npm install --save-dev jest-sorted

With yarn:

yarn add -D jest-sorted

Setup

Jest >v24

Add jest-sorted to your Jest setupFilesAfterEnv configuration. See for help

For example, add the following to your package.json at the root level. See configuring jest for more info.

"jest": {
  "setupFilesAfterEnv": ["jest-sorted"]
}

Jest <v23

"jest": {
  "setupTestFrameworkScriptFile": "jest-sorted"
}

If you are already using another test framework, like jest-chain, then you should create a test setup file and require each of the frameworks you are using.

For example:

// ./testSetup.js
require('jest-sorted');
require('jest-chain');
require('any other test framework libraries you are using');

Then in your Jest config:

"jest": {
  "setupTestFrameworkScriptFile": "./testSetup.js"
}

Typescript

• Coming soon...

Usage

toBeSorted

Passes if the array is sorted in ascending order.

expect([1, 2, 3]).toBeSorted();

options

The following options can be passed as an object to alter the assertions behaviour

• descending : boolean - Asserts the array is sorted in descending order. (Defaults to false)

expect([3, 2, 1]).toBeSorted({ descending: true });

• coerce : boolean - Coereces values to numbers before comparison. (Defaults to false) Note: consecutive NaN values after co-ercion are considered to be sorted

expect(['2', '12']).toBeSorted({ coerce: true });

• key : string - Will use the value from the passed key in an array of objects. (Used internally by the toBeSortedBy method)

expect([{ id: 1 }, { id: 2 }, { id: 3 }]).toBeSorted({ key: 'id' });

• strict : boolean - Fails the assertion if a passed key option does not exist in the object. (Defaults to true) Note: will use undefined for all missing keys and equal values are considered sorted.

expect([{ id: 1 }, { id: 2 }, { id: 3 }]).toBeSorted({
  key: 'nothing',
  strict: false,
});

• compare : function - A custom function to use for comparison. (Default comparison is a simple greater / less than). In some cases you may want to check values are sorted by a different condition. The function will take 2 elements from the array (a,b) and should return:

  • A negative number if a comes first.
  • A positive number if b comes first.
  • 0 if the values are sorted equally.

See the compareFunction of Array.prototype.sort for more info.

const doubleDigitsFirst = (a, b) => {
  if (a >= 10 && b < 10) {
    return -1;
  }
  if (b >= 10 && a < 10) {
    return 1;
  }
  return 0;
};

expect([10, 20, 1, 2]).toBeSorted({
  compare: doubleDigitsFirst,
});

toBeSortedBy

Passes if the array of objects is sorted in ascending order by the passed key. (Alias for toBeSorted({ key }))

expect([{ id: 1 }, { id: 2 }, { id: 3 }]).toBeSortedBy('id');

options

The following options can be passed as an object to alter the assertions behaviour

• descending : boolean - Asserts the array is sorted in descending order. (Defaults to false)

expect([{ id: 3 }, { id: 2 }, { id: 1 }]).toBeSortedBy('id', {
  descending: true,
});

• coerce : boolean - Coereces values to numbers before comparison. (Defaults to false) Note: consecutive NaN values after co-ercion are considered to be sorted

expect([{ count: '2' }, { count: '12' }]).toBeSortedBy('count', {
  coerce: true,
});

• strict : boolean - Fails the assertion if a passed key option does not exist in the object. (Defaults to true) Note: will use undefined for all missing keys and equal values are considered sorted.

expect([{ id: 3 }, { id: 2 }, { id: 1 }]).toBeSortedBy('nothing', {
  strict: false,
});

• compare : function - A custom function to use for comparison. (Default comparison is a simple greater / less than). In some cases you may want to check values are sorted by a different condition. The function will take 2 values from the specified keys (a,b) and should return:

  • A negative number if a comes first.
  • A positive number if b comes first.
  • 0 if the values are sorted equally.

See the compareFunction of Array.prototype.sort for more info.

const doubleDigitsFirst = (a, b) => {
  if (a >= 10 && b < 10) {
    return -1;
  }
  if (b >= 10 && a < 10) {
    return 1;
  }
  return 0;
};

expect([{ count: 10 }, { count: 20 }, { count: 1 }, { count: 2 }]).toBeSortedBy(
  'count',
  {
    compare: doubleDigitsFirst,
  }
);