bug(material/chips): MatChipSelectionChange not emitting on certain deselections
- Dominant language
- TypeScript
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Description
### Is this a regression?
- [ ] Yes, this behavior used to work in the previous version
### The previous version in which this bug was not present was
_No response_
### Description
`selectionChange` output for `MatChipOption` is [stated to be](https://material.angular.io/components/chips/api#MatChipOption):
> Emitted when the chip is selected or **deselected**.
But this is not true for deselection. It appears the event is only emitted for deselection when **the chip in question** is manually selected/toggled by the user. When the `MatChipListbox` is **in single-select mode and a chip is currently selected**, selecting a different chip means the prior chip is deselected --> deselecting should mean emitting the `selectionChange` event, but it is not happening in this scenario.
See the below StackBlitz link.
### Reproduction
StackBlitz link: https://stackblitz.com/edit/firqg1
Steps to reproduce:
(First chip is initially selected)
1. Click on the Second chip.
2. First chip becomes deselected, but no `selectionChange` output event was emitted (in this case, the `MatChipSelectionChange` object should be logged to the console).
### Expected Behavior
`selectionChange` output for the First chip should have emitted.
### Actual Behavior
`selectionChange` output for the First chip does not emit.
### Environment
- Angular: 16
- CDK/Material: 16.2.7 (latest)
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): Windows
Contributor guide
Research direction
Open the linked StackBlitz reproduction and inspect the MatChipOption and MatChipListbox selection behavior described in the issue. Verify the single-select deselection path when selecting the second chip; done means the first chip emits its MatChipSelectionChange event when it becomes deselected.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- angular, typescript
- Domain
- frontend
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100