Update toEqual failure message #7325

phapp88 · 2018-11-03T14:07:59Z

Summary

This pull request updates the failure message returned by toEqual so that it is identical to the improved message shown in #7105. The changes made are similar to the changes made in #7224.

Test plan

The matcher is tested with a snapshot test.

pedrottimark · 2018-11-18T19:58:12Z

e2e/__tests__/__snapshots__/failures.test.js.snap

-      2
-    Received:
-      1
-


This report which doesn’t display expected and received values is evidence for request to remove && !oneline

Making the change you suggested did not have any effect on this snapshot. I believe that is because jest-diff returns null if the type of the expected value is number and two numbers are being compared for this test.

CI failed because this snapshot (which now has added lines we wanted) wasn’t updated in committed files:

Expected: 2 Received: 1

pedrottimark · 2018-11-18T19:59:56Z

packages/expect/src/matchers.js

-            `  ${printReceived(received)}` +
+            matcherHint('.toEqual', undefined, undefined, {
+              isNot: this.isNot,
+            }) +
            (diffString && !oneline ? `\n\nDifference:\n\n${diffString}` : '')


Can you please remove && !oneline so the report displays expected and received values even if one line.

pedrottimark · 2018-11-18T20:03:26Z

@phapp88 Thank you. Please forgive the delay to review your work. I requested one change.

codecov-io · 2018-11-19T19:53:26Z

Codecov Report

Merging #7325 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #7325      +/-   ##
==========================================
- Coverage   66.64%   66.64%   -0.01%     
==========================================
  Files         241      241              
  Lines        9345     9344       -1     
  Branches        6        5       -1     
==========================================
- Hits         6228     6227       -1     
  Misses       3114     3114              
  Partials        3        3

Impacted Files	Coverage Δ
packages/expect/src/matchers.js	`99.37% <100%> (-0.01%)`	⬇️

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pedrottimark · 2018-11-19T20:31:26Z

Yes, my bad, jest-diff does return one-line diff for string args, but null for number or boolean.

expect('received').toEqual('expected'); // diffString is string
expect(1).toEqual(0); // diffString is null
expect(true).toEqual(false); // diffString is null

Therefore, it looks like we need the following EDIT in the second message function:

return (
  matcherHint('.toEqual', undefined, undefined, {
    isNot: this.isNot,
  }) +
  '\n\n' +
  (diffString
    ? `Difference:\n\n${diffString}`
    : `Expected: ${printExpected(expected)}\n` +
      `Received: ${printReceived(received)}`)
);

pedrottimark · 2018-11-19T23:17:35Z

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

-  <green>-0</>
-Received:
-  <red>0</>
-
 Difference:

 <dim>Compared values have no visual difference.</>"


This is because jest-diff use strict equality === operator when Object.is might be better.

That would be a separate pull request.

we should land that on master, then rebase this, right? To ensure the message is good

pedrottimark · 2018-11-19T23:18:41Z

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

-  <green>ArrayContaining [1, 2]</>
-Received:
-  <red>1</>
-
 Difference:

  Comparing two different types of values. Expected <green>array</> but received <red>number</>."


This might be a problem though.

pedrottimark · 2018-11-19T23:29:43Z

@phapp88 Thank you for your patient follow through. It might be until Wednesday before my mental slow cooker has suggestion what to do about edge cases from jest-diff package.

phapp88 · 2018-11-19T23:38:23Z

@pedrottimark No problem. I'd be willing to submit other pull requests related to jest-diff to help resolve these issues.

pedrottimark · 2018-11-20T14:09:09Z

Here is another condition to display Expected and Received values when jest-diff returns:

Compared values have no visual difference.
Comparing two different types of values.

EDIT incorrect: RegExp because node.green displays String.prototype.includes as red for early 6.x versions

Not anchored at start because of escape sequences for green and red color.

const diffString = diff(expected, received, {expand: this.expand});

return (
  matcherHint('.toEqual', undefined, undefined, {
    isNot: this.isNot,
  }) +
  '\n\n' +
  (diffString && diffString.includes('- Expect')
    ? `Difference:\n\n${diffString}`
    : `Expected: ${printExpected(expected)}\n` +
      `Received: ${printReceived(received)}`)
);

The memory is coming back: these tedious details are why this matcher was left until later :)

SimenB · 2018-11-20T14:49:20Z

expect(1).toEqual(0); // diffString is null
expect(true).toEqual(false); // diffString is null

That's a bug, no?

pedrottimark · 2018-11-20T15:00:10Z

@SimenB hard to say if bug or feature: jest-diff package returns null for some edge cases:

number
boolean
asymmetric matchers

I got stuck at the beginning of 2018 thinking about consequences of changing its contract, so now am looking for ways to move forward on expect package, despite the tighter-than-ideal coupling in my suggestions above.

By the way, can you give a second opinion about https://github.com/facebook/jest/blob/master/packages/jest-diff/src/index.js#L53-L55

I think instead of a === b it should be Object.is(a, b) to deal with 0/-0 and NaN, true?

SimenB · 2018-11-20T15:13:57Z

I think instead of a === b it should be Object.is(a, b) to deal with 0/-0 and NaN, true?

Yes 🙂

SimenB · 2018-11-20T15:16:09Z

RegExp because node.green displays String.prototype.includes as red for early 6.x versions

It's been in Node since v4? https://node.green/#ES2015-built-in-extensions-String-prototype-methods-String-prototype-includes

pedrottimark · 2018-11-20T15:18:31Z

You are correct. My bad, I think I misunderstood a table row under well-known symbols.

pedrottimark · 2018-11-21T19:20:05Z

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

-
-Difference:
-
-<dim>Compared values have no visual difference.</>"


Super that the work-around fixed this existing problem.

pedrottimark · 2018-11-21T19:20:48Z

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

-
-Difference:
-
-  Comparing two different types of values. Expected <green>array</> but received <red>number</>."


Bravo, also fixed this problem.

thymikee · 2019-01-09T20:46:57Z

packages/expect/src/matchers.js

-            `Received:\n` +
-            `  ${printReceived(received)}` +
-            (diffString && !oneline ? `\n\nDifference:\n\n${diffString}` : '')
+            (diffString && diffString.includes('- Expect')


@pedrottimark it's not particular fault of this PR, but generally why do we show diffString in this branch, but not on the other? Looking at the snapshots and seeing the diff sometimes shown for one-liners and sometimes not is weird :|

Good question about the asymmetry: first branch means that .not.toBe fails, therefore not likely to have differences. For some other matchers the expected might be asymmetric.

thymikee · 2019-01-09T20:48:58Z

packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap

+<red>+ Received</>
+
+<green>- apple</>
+<red>+ banana</>"


shouldn't this be shown as:

Expected: apple Received: banana

?
It's weird seeing the diff for single lines, when Expected/Received fits better for this purpose

Yeah, the reason is maybe in the future to display substring differences.

thymikee

Most of the diff looks better, so I'm keen on getting this to master and iterate on the edge cases causing showing the full "Difference: " message for single-line values

pedrottimark · 2019-01-09T21:00:25Z

@phapp88 thank you for contributing to Jest

* Update toEqual failure message * Update changelog * Update failing snapshots * Show one line reports * Update failure message when diffString is null * Update failing snapshot * Update failure message for jest-diff edge cases

github-actions · 2021-05-12T04:08:50Z

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.

Update toEqual failure message

9c1805c

facebook-github-bot added the cla signed label Nov 3, 2018

phapp88 added 2 commits November 3, 2018 09:12

Update changelog

e48ab17

Update failing snapshots

a53843d

pedrottimark suggested changes Nov 18, 2018

View reviewed changes

Show one line reports

d316498

phapp88 added 2 commits November 19, 2018 15:22

Update failure message when diffString is null

09dbb4c

Update failing snapshot

27bd705

pedrottimark reviewed Nov 19, 2018

View reviewed changes

Update failure message for jest-diff edge cases

2b9e208

pedrottimark reviewed Nov 21, 2018

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pedrottimark approved these changes Nov 21, 2018

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Merge branch 'master' into update-toEqual

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thymikee reviewed Jan 9, 2019

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thymikee approved these changes Jan 9, 2019

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pedrottimark merged commit 6cc2a85 into jestjs:master Jan 9, 2019

phapp88 deleted the update-toEqual branch January 9, 2019 21:57

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Update toEqual failure message #7325

Update toEqual failure message #7325

phapp88 commented Nov 3, 2018

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		Difference:

		<dim>Compared values have no visual difference.</>"

Update toEqual failure message #7325

Update toEqual failure message #7325

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phapp88 commented Nov 3, 2018

Summary

Test plan

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pedrottimark commented Nov 18, 2018

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