Structural directives can now specify a type guard that describes
what types can be inferred for an input expression inside the
directive's template.
NgIf was modified to declare an input guard on ngIf.
After this change, `fullTemplateTypeCheck` will infer that
usage of `ngIf` expression inside it's template is truthy.
For example, if a component has a property `person?: Person`
and a template of `<div *ngIf="person"> {{person.name}} </div>`
the compiler will no longer report that `person` might be null or
undefined.
The template compiler will generate code similar to,
```
if (NgIf.ngIfTypeGuard(instance.person)) {
instance.person.name
}
```
to validate the template's use of the interpolation expression.
Calling the type guard in this fashion allows TypeScript to infer
that `person` is non-null.
Fixes: #19756?
PR Close#20702
Add enough BUILD files to make it possible to
`bazel build packages/core/test`
Also re-format BUILD.bazel files with Buildifier.
Add a CI lint check that they stay formatted.
PR Close#20768
Throwing an exception in a lifecycle event will delay but not
prevent an Init method, such as `ngOnInit`, `ngAfterContentInit`,
or `ngAfterViewInit`, from being called. Also, calling `detectChanges()`
in a way that causes duplicate change detection (such as a
child component causing a parent to call `detectChanges()` on its
own `ChangeDetectorRef`, will no longer prevent change `ngOnInit`,
`ngAfterContentInit` and `ngAfterViewInit` from being called.
With this change lifecycle methods are still not guarenteed to be
called but the Init methods will be called if at least one change
detection pass on its view is completed.
Fixes: #17035
PR Close#20258
This allows to overwrite templates for JIT and AOT components alike.
In contrast to `TestBed.overrideTemplate`, the template is compiled
in the context of the testing module, allowing to use other testing
directives.
Closes#19815
Before, as soon as a user called `TestBed.overrideProvider` for a provider
of a `NgModule` that was imported via `TestBed.configureTestingModule`,
that `NgModule` became lazy.
This commit changes this behavior to keep the `NgModule` eager,
with or without a call to `TestBed.overrideProvider`.
PR Close#19624
This allows use to fix `TestBed.overrideProvider` to keep imported `NgModule`s eager,
while allowing our users to still keep the old semantics until they have fixed their
tests.
PR Close#19558
