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How does mocha show the whole object in diff on a statement error?

I have a unit unit test case created using mocha and chai, waiting where I deeply compare an array of value objects with the parsed content of a JSON file.

My recording object has about 20 properties, and currently only the price can cause a mismatch. On diff, I see only five of them.

 expect(records).to.deep.equal(expected);

       "data": {
  -      "price": 3578
  +      "price": 3438
         "not_important": "foo"
         "also_not_important": "bar"
       }
       "data": {
  -      "price": 1828
  +      "price": 1698
         "not_important": "foo"
         "also_not_important": "bar"
       }

In most cases, this is useful by default, but in this it confuses which particular data object violates the assertions, since here I see only redundant data.

Suppose there is a property in the data object importantthat makes it completely clear what expectation the test breaks. Therefore, I would like to be able to either configure what properties will be shown, or display the entire object in diff.

mocha diff?

, :

import {expect} from "chai";

describe(("diff problem"), () => {
    it("should show case that the diff is not shown properly", () => {
        const actual = {
            a: 1,
            troiz: 0,
            bar: 0,
            baz: 2,
            poit: 3,
            narf: 4,
            fizzbuzz: 117,
            fizz: 5,
            buzz: 4,
            waldo: 115,
            mos: 85465,
            important: "THIS IS IMPORTANT",
        };

        const expected = {
            ...actual,
            a: 0,
        };

        return expect(actual).to.deep.equal(expected);
    });
});

:

2) SourceParser diff :

  AssertionError: expected { Object (a, troiz, ...) } to deeply equal { Object (a, troiz, ...) }
  + expected - actual

   {
  -  "a": 1
  +  "a": 0
     "bar": 0
     "baz": 2
     "buzz": 4
     "fizz": 5

: important: "THIS IS IMPORTANT".

:

describe(("diff problem with an array"), () => {
    it("should show case that the diff is not shown properly for deep equal of arrays", () => {
        const anEntity = {
            a: 1,
            troiz: 0,
            bar: 0,
            baz: 2,
            poit: 3,
            narf: 4,
            fizzbuzz: 117,
            fizz: 5,
            buzz: 4,
            waldo: 115,
            mos: 85465,
            important: "IMPORTANT", // assume that each item has a unique important property, which is why it helpful for it to be shown
        };

        const offendingItem = {
            ...anEntity,
            a: 0,
        };

        const actual = [
            anEntity,
            offendingItem,
            anEntity,
        ];

        const expected = [
            anEntity,
            anEntity,
            anEntity,
        ];

        return expect(actual).to.deep.equal(expected);
    });

:

  AssertionError: expected [ Array(3) ] to deeply equal [ Array(3) ]
  + expected - actual

       "troiz": 0
       "waldo": 115
     }
     {
  -    "a": 0
  +    "a": 1
       "bar": 0
       "baz": 2
       "buzz": 4
       "fizz": 5

, chai, , diff:

AssertionError: expected [ { a: 1,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' },
  { a: 0,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' },
  { a: 1,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' } ] to deeply equal [ { a: 1,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' },
  { a: 1,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' },
  { a: 1,
    troiz: 0,
    bar: 0,
    baz: 2,
    poit: 3,
    narf: 4,
    fizzbuzz: 117,
    fizz: 5,
    buzz: 4,
    waldo: 115,
    mos: 85465,
    important: 'IMPORTANT' } ]
      + expected - actual

           "troiz": 0
           "waldo": 115
         }
         {
      -    "a": 0
      +    "a": 1
           "bar": 0
           "baz": 2
           "buzz": 4
           "fizz": 5
+9
3

--inline-diffs mocha, :

mocha --inline-diffs YourSpec.js

: https://mochajs.org/#diffs

The mocha result

+1

, Chai Mocha diff, , diff, , . , , . .

truncateThreshold 0 , , diff, . , :

chai.config.truncateThreshold = 0; // 0 means "don't truncate, ever".

( .)

, :

      AssertionError: expected { a: 1,
  troiz: 0,
  bar: 0,
  baz: 2,
  poit: 3,
  narf: 4,
  fizzbuzz: 117,
  fizz: 5,
  buzz: 4,
  waldo: 115,
  mos: 85465,
  important: 'THIS IS IMPORTANT' } to deeply equal { a: 0,
  troiz: 0,
  bar: 0,
  baz: 2,
  poit: 3,
  narf: 4,
  fizzbuzz: 117,
  fizz: 5,
  buzz: 4,
  waldo: 115,
  mos: 85465,
  important: 'THIS IS IMPORTANT' }
      + expected - actual

       {
      -  "a": 1
      +  "a": 0
         "bar": 0
         "baz": 2
         "buzz": 4
         "fizz": 5

, - , :

expect(actual).to.deep.equal(
            expected,
            'failed equality test on object with important field set to: ${actual.important}')

, .

, , .

, actual expected . , . , : , 1 10 , 1, . , 10. , , , .

, , , , - , , , , . , .

, , , . , actual expected , , .

+8

- : . . , , . , .

. - .

- .

, . .

-5

Source: https://habr.com/ru/post/1684464/

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