Jest Array toContain does not work with objects - Improve documentation example

Do you want to request a feature or report a bug?

This is (I suspect) a bug report

What is the current behavior?

Jest expect(Array).toContain(Object) does not work in one very simple case

Here is a demo showing the (I suspect) bug: https://repl.it/@SandinoNunez/Testing-jest-toContain-Method

What is the expected behavior?

Jest expect(Array).toContain(Object) should work correctly

Please provide your exact Jest configuration

"jest": {
    "transform": {
      "^.+\\.js?$": "babel-jest"
    },
    "transformIgnorePatterns": [
      "!node_modules/react-runtime"
    ],
    "testMatch": [
      "<rootDir>/lib/components/**/__tests__/**/*.js?(x)",
      "<rootDir>/lib/**/__tests__/**/*.js?(x)",
      "**/?(*.).js?(x)"
    ],
    "setupTestFrameworkScriptFile": "./node_modules/jest-enzyme/lib/index.js",
    "coverageThreshold": {
      "collectCoverage": true,
      "coverageFormats": [
        "json",
        "html"
      ],
      "global": {
        "branches": 80,
        "functions": 90,
        "lines": 80,
        "statements": 80
      },
      "./lib/widget/widget.js": {
        "branches": 90,
        "functions": 90,
        "lines": 90,
        "statements": 90
      },
      "./lib/utils/*.js": {
        "branches": 70,
        "functions": 70,
        "lines": 70,
        "statements": 70
      }
    }
  },

Jest version: 22.1.2

[peoray]

In case anyone comes across this same issue, use this instead of what has been suggested .toMatchObject

Here is the reference

[sandinosaso]

I figured out that using toContainEqual does exactly what I was looking for.

Is confusing that the function accepts an object as value but it does not work as intended. The message makes the user believe that something is wrong but you see your object is contained in the array so can not figure out why the test is failing.

This is the output:

` expect(array).toContain(value)

Expected array:
  [{"attr1": "attr1 value", "attr2": true}]
To contain value:
  {"attr1": "attr1 value", "attr2": true}

`

I found the toContainEqualafter looking at the source code to see why the object comparison was not working and maybe try to fix it.

I think we can include an example usage here: https://facebook.github.io/jest/docs/en/using-matchers.html

Let me know what you think I can close this issue and open a PR for documentation update if you think that is necessary.