doc: add guides on writing tests involving promises #20988
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Mention `common.crashOnUnhandledRejection()` and wrapping the handlers in `common.mustCall()` or `common.mustNotCall()`
vsemozhetbyt
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test
vsemozhetbyt
approved these changes
May 27, 2018
doc/guides/writing-tests.md
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| When writing tests involving promises, either make sure that the | ||
| `onFulfilled` or the `onRejected` handler is wrapped in | ||
| `common.mustCall()` or `common.mustNotCall` accordingly, or |
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common.mustNotCall -> common.mustNotCall()?
doc/guides/writing-tests.md
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| const fs = require('fs').promises; | ||
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| // Use `common.crashOnUnhandledRejection()` to make sure unhandled rejections | ||
| // will fail the test |
doc/guides/writing-tests.md
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| // will fail the test | ||
| common.crashOnUnhandledRejection(); | ||
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| // Or, wrap the `onRejected` handler in `common.mustNotCall()` |
doc/guides/writing-tests.md
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| // Or, wrap the `onRejected` handler in `common.mustNotCall()` | ||
| fs.writeFile('test-file', 'test').catch(common.mustNotCall()); | ||
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| // Or, wrap the `onFulfilled` handler in `common.mustCall()` |
doc/guides/writing-tests.md
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| (content) => assert.strictEqual(content.toString(), 'test') | ||
| )); | ||
| ``` | ||
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lpinca
reviewed
May 27, 2018
doc/guides/writing-tests.md
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| fs.readFile('test-file').then( | ||
| common.mustCall( | ||
| (content) => assert.strictEqual(content.toString(), 'test') | ||
| )); |
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It's an example, but I think it makes sense to add catch() to handle the case where the assertion fails.
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@lpinca that is demonstrated in the first example...also the onFullfilled and the onRejected handler are mutually exclusive so common.mustCall should be able to catch that.
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I'm not sure I understand, this
const common = require('../common');
const assert = require('assert');
const fs = require('fs');
const fsPromises = fs.promises;
fs.writeFileSync('test-file', 'foo');
fsPromises.readFile('test-file').then(
common.mustCall((content) => {
assert.strictEqual(content.toString(), 'test');
})
);should make the test fails, but it doesn't if common.crashOnUnhandledRejection(); is not added.
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@lpinca I see what you mean now, the catch needs to handle possible failures if the onFulfilled handler is not empty. Thanks for catching that!
danbev
approved these changes
May 28, 2018
lpinca
approved these changes
May 28, 2018
BridgeAR
approved these changes
May 28, 2018
BridgeAR
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trivikr
approved these changes
May 28, 2018
jasnell
approved these changes
May 29, 2018
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Landed in df16d20 |
apapirovski
pushed a commit
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Jun 1, 2018
Mention `common.crashOnUnhandledRejection()` and wrapping the handlers in `common.mustCall()` or `common.mustNotCall()`. PR-URL: #20988 Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
MylesBorins
pushed a commit
that referenced
this pull request
Jun 6, 2018
Mention `common.crashOnUnhandledRejection()` and wrapping the handlers in `common.mustCall()` or `common.mustNotCall()`. PR-URL: #20988 Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
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Mention
common.crashOnUnhandledRejection()and wrapping thehandlers in
common.mustCall()orcommon.mustNotCall()Checklist
make -j4 test(UNIX), orvcbuild test(Windows) passes