fix(1845): CSS special selector ":host" only work first time

[m-abs]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/nativescript-angular/blob/master/DevelopmentWorkflow.md#running-the-tests
• Tests for the changes are included.

I can't run the unit tests, so I couldn't write a test for this fix.

What is the current behavior?

:host selector only works for on first instance of a component.

This is caused by _nghost-%COMP%-property only being applied when the EmulatedRenderer is created for a type, but not when it is reuse.

What is the new behavior?

The _nghost-%COMP%-property is applied when the EmulatedRenderer is reused.

Fixes #1845

[VladimirAmiorkov]

run ci

[VladimirAmiorkov]

Hi @m-abs ,

Thank you for this contribution. Can you share with me a code sample that shows the incorrect case when using :host so we can add a test for this case ?

[m-abs]

Hi @VladimirAmiorkov

I wouldn't mind writing a test myself, but as I wrote before I can't run the test project.

There is a playground project in the bug rapport: https://play.nativescript.org/?template=play-ng&id=NXYfcY&v=15

But I can give a quick example here:

Template:

<Label [text]="textValue"></Label>

Stylesheet:

Label { background-color: green; font-weight: normal; font-size: 12; horizontal-align: left; } :host Label { background-color: blue; font-weight: bold; font-size: 20; horizontal-align: center; }

This should demonstrate the problem, if the component is used more than once.

[VladimirAmiorkov]

Hi @m-abs ,

Thank you for the details. I am currently working on resolving the issues in the tests app that are caused by the --bundle option. Can you try to run it with the legacy workflow that does not trigger --bundle ?

[m-abs]

Hi @VladimirAmiorkov

I managed to run the tests without --bundle, so I could add my test.