mirror of
https://github.com/idanoo/GoScrobble.git
synced 2024-11-23 00:45:16 +00:00
173 lines
3.6 KiB
Markdown
173 lines
3.6 KiB
Markdown
# disallow large snapshots (`no-large-snapshots`)
|
|
|
|
When using Jest's snapshot capability one should be mindful of the size of
|
|
created snapshots. As a general best practice snapshots should be limited in
|
|
size in order to be more manageable and reviewable. A stored snapshot is only as
|
|
good as its review and as such keeping it short, sweet, and readable is
|
|
important to allow for thorough reviews.
|
|
|
|
## Usage
|
|
|
|
Because Jest snapshots are written with back-ticks (\` \`) which are only valid
|
|
with
|
|
[ES2015 onwards](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals)
|
|
you should set `parserOptions` in your config to at least allow ES2015 in order
|
|
to use this rule:
|
|
|
|
```js
|
|
module.exports = {
|
|
parserOptions: {
|
|
ecmaVersion: 2015,
|
|
},
|
|
};
|
|
```
|
|
|
|
## Rule Details
|
|
|
|
This rule looks at all Jest inline and external snapshots (files with `.snap`
|
|
extension) and validates that each stored snapshot within those files does not
|
|
exceed 50 lines (by default, this is configurable as explained in `Options`
|
|
section below).
|
|
|
|
Example of **incorrect** code for this rule:
|
|
|
|
```js
|
|
exports[`a large snapshot 1`] = `
|
|
line 1
|
|
line 2
|
|
line 3
|
|
line 4
|
|
line 5
|
|
line 6
|
|
line 7
|
|
line 8
|
|
line 9
|
|
line 10
|
|
line 11
|
|
line 12
|
|
line 13
|
|
line 14
|
|
line 15
|
|
line 16
|
|
line 17
|
|
line 18
|
|
line 19
|
|
line 20
|
|
line 21
|
|
line 22
|
|
line 23
|
|
line 24
|
|
line 25
|
|
line 26
|
|
line 27
|
|
line 28
|
|
line 29
|
|
line 30
|
|
line 31
|
|
line 32
|
|
line 33
|
|
line 34
|
|
line 35
|
|
line 36
|
|
line 37
|
|
line 38
|
|
line 39
|
|
line 40
|
|
line 41
|
|
line 42
|
|
line 43
|
|
line 44
|
|
line 45
|
|
line 46
|
|
line 47
|
|
line 48
|
|
line 49
|
|
line 50
|
|
line 51
|
|
`;
|
|
```
|
|
|
|
Example of **correct** code for this rule:
|
|
|
|
```js
|
|
exports[`a more manageable and readable snapshot 1`] = `
|
|
line 1
|
|
line 2
|
|
line 3
|
|
line 4
|
|
`;
|
|
```
|
|
|
|
## Options
|
|
|
|
This rule has options for modifying the max number of lines allowed for a
|
|
snapshot:
|
|
|
|
In an `eslintrc` file:
|
|
|
|
```json
|
|
{
|
|
"rules": {
|
|
"jest/no-large-snapshots": ["warn", { "maxSize": 12, "inlineMaxSize": 6 }]
|
|
}
|
|
}
|
|
```
|
|
|
|
Max number of lines allowed could be defined by snapshot type (Inline and
|
|
External). Use `inlineMaxSize` for
|
|
[Inline Snapshots](https://jestjs.io/docs/en/snapshot-testing#inline-snapshots)
|
|
size and `maxSize` for
|
|
[External Snapshots](https://jestjs.io/docs/en/snapshot-testing#snapshot-testing-with-jest).
|
|
If only `maxSize` is provided on options, the value of `maxSize` will be used to
|
|
both snapshot types (Inline and External).
|
|
|
|
Since `eslint-disable` comments are not preserved by Jest when updating
|
|
snapshots, you can use the `allowedSnapshots` option to have specific snapshots
|
|
allowed regardless of their size.
|
|
|
|
This option takes a map, with the key being the absolute filepath to a snapshot
|
|
file, and the value an array of values made up of strings and regular
|
|
expressions to compare to the names of the snapshots in the `.snap` file when
|
|
checking if the snapshots size should be allowed.
|
|
|
|
Note that regular expressions can only be passed in via `.eslintrc.js` as
|
|
instances of `RegExp`.
|
|
|
|
In an `.eslintrc.js` file:
|
|
|
|
```javascript
|
|
module.exports = {
|
|
rules: {
|
|
'jest/no-large-snapshots': [
|
|
'error',
|
|
{
|
|
allowedSnapshots: {
|
|
'/path/to/file.js.snap': ['snapshot name 1', /a big snapshot \d+/],
|
|
},
|
|
},
|
|
],
|
|
},
|
|
};
|
|
```
|
|
|
|
Since absolute paths are typically not very portable, you can use the builtin
|
|
`path.resolve` function to expand relative paths into absolutes like so:
|
|
|
|
```javascript
|
|
const path = require('path');
|
|
|
|
module.exports = {
|
|
rules: {
|
|
'jest/no-large-snapshots': [
|
|
'error',
|
|
{
|
|
allowedSnapshots: {
|
|
[path.resolve('test/__snapshots__/get.js.snap')]: ['full request'],
|
|
[path.resolve('test/__snapshots__/put.js.snap')]: ['full request'],
|
|
},
|
|
},
|
|
],
|
|
},
|
|
};
|
|
```
|