feat: adding extendsFromRoot option via forRoot() module configur…

…ation (#138)

README.md

@@ -118,6 +118,59 @@ export class YourAppComponent {}
 </div>
 ```
 
+#### Extending `theme` via `NgxSkeletonLoaderModule.forRoot()`
+
+> By default when using `NgxSkeletonLoaderModule.forRoot({ theme: /* ...list of CSS atributes */} })` the application is using this value as source of truth, overriding any local theming passed to `<ngx-skeleton-loader>` component via `[theme]` input. Check these steps in case you need to change this behaviour in your app
+
+This method is also accepting the option of having a global theme and local theme inputs. You can enable it by passing `NgxSkeletonLoaderModule.forRoot({ theme: { extendsFromRoot: true, /* ...list of CSS atributes */} })` in your module. Quite simple, right? 😄
+
+By using that configuration in yuor application, you should also be aware that:
+
+- By default, every `<ngx-skeleton-loader>` component will use `theme` coming from `NgxSkeletonLoaderModule.forRoot()` as the source of truth
+- If there's any CSS attribute on the component locally which overrides the CSS spec, it combines both themes, but overriding global CSS attributes in favor of local ones.
+
+As an example:
+
+```typescript
+...
+import { NgxSkeletonLoaderModule } from 'ngx-skeleton-loader';
+...
+
+@NgModule({
+  declarations: [
+    YourAppComponent
+  ],
+  imports: [
+    ...
+    NgxSkeletonLoaderModule.forRoot({
+      theme: {
+        // Enabliong theme combination
+        extendsFromRoot: true,
+        // ... list of CSS theme attributes
+        height: '30px',
+      },
+    }),,
+    ...
+  ],
+  providers: [],
+  bootstrap: [YourAppComponent]
+})
+
+export class YourAppComponent {}
+
+```
+
+```html
+<div class="item">
+  <ngx-skeleton-loader></ngx-skeleton-loader>
+  <!-- above line will produce a skeleton component using `height: 30px;`" -->
+  <ngx-skeleton-loader [theme]="{background: 'blue'}"></ngx-skeleton-loader>
+  <!-- above line will produce a skeleton component using `height: 30px; background: red;`" -->
+  <ngx-skeleton-loader [theme]="{height: '50px', background: 'red'}"></ngx-skeleton-loader>
+  <!-- above line will produce a skeleton component using `height: 50px; background: red;`" -->
+</div>
+```
+
 ## WAI-ARIA values
 
 - loadingText - _default_ `Loading...`: attribute that defines the text value for `aria-valuetext` attribute. Defaults to "Loading..."

projects/ngx-skeleton-loader/src/lib/ngx-skeleton-loader-config.types.ts

@@ -1,6 +1,8 @@
 import { InjectionToken } from '@angular/core';
 
 export type NgxSkeletonLoaderConfigTheme = {
+  // It enforces a combination of `fromRoot` styles with component `styles` attribute
+  extendsFromRoot?: boolean;
   // This is required since ngStyle is using `any` as well
   // More details in https://angular.io/api/common/NgStyle
   // eslint-disable-next-line @typescript-eslint/no-explicit-any

projects/ngx-skeleton-loader/src/lib/ngx-skeleton-loader.component.ts

@@ -51,7 +51,7 @@ export class NgxSkeletonLoaderComponent implements OnInit, AfterViewInit, OnDest
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   items: Array<any>;
 
-  constructor(@Inject(NGX_SKELETON_LOADER_CONFIG) @Optional() config?: NgxSkeletonLoaderConfig) {
+  constructor(@Inject(NGX_SKELETON_LOADER_CONFIG) @Optional() private config?: NgxSkeletonLoaderConfig) {
     const {
       appearance = 'line',
       animation = 'progress',
@@ -123,6 +123,11 @@ export class NgxSkeletonLoaderComponent implements OnInit, AfterViewInit, OnDest
       }
       this.appearance = '';
     }
+
+    if (Boolean(this.config?.theme?.extendsFromRoot) && this.theme !== null) {
+      // Shows error message only in Development
+      this.theme = { ...this.config!.theme, ...this.theme };
+    }
   }
 
   ngOnChanges(changes: SimpleChanges) {

projects/ngx-skeleton-loader/src/lib/ngx-skeleton-loader.module.spec.ts

@@ -8,7 +8,10 @@ import { NgxSkeletonLoaderModule } from './ngx-skeleton-loader.module';
   template: `
     <div>
       <div class="skeletons-defaults">
-        <ngx-skeleton-loader></ngx-skeleton-loader>
+        <ngx-skeleton-loader [theme]="{ width: '70px' }"></ngx-skeleton-loader>
+      </div>
+      <div class="skeletons-extended-theme">
+        <ngx-skeleton-loader [theme]="{ width: '100px', background: 'blue' }"></ngx-skeleton-loader>
       </div>
     </div>
   `,
@@ -19,20 +22,44 @@ describe('NgxSkeletonLoaderModule method', () => {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   let fixture: any;
 
-  beforeEach(
-    waitForAsync(() => {
-      spyOn(console, 'error');
-      spyOn(console, 'log');
-      spyOn(console, 'warn');
-      spyOn(console, 'info');
-      fixture = TestBed.configureTestingModule({
-        imports: [NgxSkeletonLoaderModule.forRoot({ appearance: 'circle', count: 3 })],
-        declarations: [ContainerComponent],
-        providers: [{ provide: PLATFORM_ID, useValue: 'browser' }],
-      }).createComponent(ContainerComponent);
-      fixture.detectChanges();
-    }),
-  );
+  beforeEach(waitForAsync(() => {
+    spyOn(console, 'error');
+    spyOn(console, 'log');
+    spyOn(console, 'warn');
+    spyOn(console, 'info');
+    fixture = TestBed.configureTestingModule({
+      imports: [
+        NgxSkeletonLoaderModule.forRoot({
+          appearance: 'circle',
+          count: 3,
+          theme: {
+            extendsFromRoot: true,
+            background: 'red',
+          },
+        }),
+      ],
+      declarations: [ContainerComponent],
+      providers: [{ provide: PLATFORM_ID, useValue: 'browser' }],
+    }).createComponent(ContainerComponent);
+    fixture.detectChanges();
+  }));
+
+  describe('When #forRoot receives a `theme`', () => {
+    it('should render skeleton extending theme styles from root and overriding config theming in favour of local theme if local config has any similar CSS attribute', () => {
+      const skeletonWithTheming = fixture.nativeElement.querySelector(
+        '.skeletons-extended-theme .skeleton-loader.circle',
+      ).attributes as NamedNodeMap;
+
+      expect((skeletonWithTheming.getNamedItem('style') as Attr).value).toBe('background: blue; width: 100px;');
+    });
+
+    it('should render skeleton with styles extending/combining theme styles from root if CSS attributes are not similar', () => {
+      const skeletonWithTheming = fixture.nativeElement.querySelector('.skeletons-defaults .skeleton-loader.circle')
+        .attributes as NamedNodeMap;
+
+      expect((skeletonWithTheming.getNamedItem('style') as Attr).value).toBe('background: red; width: 70px;');
+    });
+  });
 
   it('should render the component properly using given forRoot() config', () => {
     expect(fixture.nativeElement.querySelectorAll('.skeletons-defaults .skeleton-loader.circle').length).toBe(3);