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92 lines
3.1 KiB
Markdown
92 lines
3.1 KiB
Markdown
# @datashard/snapshot
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> Adds JSON Snapshot comparison to Cypress
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## ⚠️ Breaking Changes ⚠️
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- With V3, the `readFileMaybe` task has been removed, we now rely on `cy.fixture` internally.
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- the previous `SNAPSHOT_UPDATE` Environment/Config Variable has been changed to `updateSnapshots`
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> [!DANGER]
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This means that previous tests will likely be broken, *please make sure that your tests pass before updating to the latest version of this Plugin*.
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This current release will be released as `3.0.0-beta`, should Bugs be found by me or my Employer, I will open Issues/PRs to fix those, should anyone else find Bugs/Edgecases, etc. please open an Issue.
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## Install
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Requires Node 16 or above
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```sh
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npm i --save-dev @datashard/snapshot
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```
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## Import
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After Installing, you'll need to add the following import into your Commands/Support File
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> by default this will be `cypress/support/e2e.js`
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```js
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require('@datashard/snapshot').regsiter()
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```
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This will register a new Command `.snapshot()`, to create and compare JSON Snapshots.
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## Config
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You can pass `updateSnapshots` and `useFolders` as options in the `cypress.config.js` file
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Alternatively, you can also add `snapshotUpdate` as an Environment Variable to update your snapshots.
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Simply pass `--env updateSnapshots=true` when running Cypress.
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## Usage
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If properly added, usage of this plugin is rather simple, just add `.snapshot()` to cypress functions that return valid JSON. (i.e. `cy.wrap`)
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When properly added, you can chain `.snapshot()` off of `cy` functions like `cy.wrap`, just make sure they return valid JSON.
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### Example
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```js
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describe("my test", () => {
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it("works", () => {
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cy.log("first snapshot");
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cy.wrap({ foo: 42 }).snapshot("foo");
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cy.log("second snapshot");
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cy.wrap({ bar: 101 }).snapshot("bar");
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});
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});
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```
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This Plugin will then save your snapshots as
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```ts
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// useFolders: false
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cypress/fixtures/my-test__works__foo.json
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cypress/fixtures/my-test__works__bar.json
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// useFolders: true
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cypress/fixtures/my-test/works/foo.json
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cypress/fixtures/my-test/works/bar.json
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// {fixtureFolder}/<Context>-<Describe>-<It>-<Name?>.json
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// {fixtureFolder}/<Context>/<Describe>/<It>/<Name?>.json
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```
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Snapshots will generally be saved using this the Convention mentioned in the Comment of the above Codeblock, which is provided by the named Cypress Test Steps.
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Passing a name to the Snapshot function is required, but not checked, if you want to take multiple snapshots in the same block.
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If you have two or more Snapshots in the same Block, the next one ***WILL*** always overwrite the previous one while updating, causing the First Snapshot in the Block to Fail.
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While running your Tests, if a value changed, it will, of course, no longer match the snapshot and throw an Error.
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Which will look like this:
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When the Test succeeds, it will instead log a Success in the Log and let you know where the File has been saved to, relative to the Fixture Snapshot Folder
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