fix(ngClass): add ngClass selector support (#223)

*  add missing static `ngClass` and `class`  selectors
*  add tests to demonstrate fallbacks to static selector values

Fixes #206.

Author: ThomasBurleson

src/lib/flexbox/api/class.spec.ts

@@ -71,6 +71,22 @@ describe('class directive', () => {
         </div>
     `);
 
+    expectNativeEl(fixture).toHaveCssClass('existing-class');
+    activateMediaQuery('xs');
+    expectNativeEl(fixture).not.toHaveCssClass('existing-class');
+
+    activateMediaQuery('lg');
+    expectNativeEl(fixture).toHaveCssClass('existing-class');
+    expectNativeEl(fixture).not.toHaveCssClass('xs-class');
+  });
+
+  it('should keep existing ngClass selector', () => {
+    // @see documentation for @angular/core ngClass =http://bit.ly/2mz0LAa
+    fixture = createTestComponent(`
+          <div ngClass="existing-class" ngClass.xs="existing-class xs-class">
+          </div>
+      `);
+
     expectNativeEl(fixture).toHaveCssClass('existing-class');
     activateMediaQuery('xs');
     expectNativeEl(fixture).toHaveCssClass('existing-class');
@@ -80,7 +96,7 @@ describe('class directive', () => {
     expectNativeEl(fixture).not.toHaveCssClass('xs-class');
   });
 
-  it('should allow more than one responsive breakpoint on one element', () => {
+  it('should support more than one responsive breakpoint on one element', () => {
     fixture = createTestComponent(`
                 <div ngClass.xs="xs-class"
                   ngClass.md="md-class">
@@ -96,7 +112,8 @@ describe('class directive', () => {
 
   it('should work with ngClass object notation', () => {
     fixture = createTestComponent(`
-        <div [ngClass.xs]="{'xs-1': hasXs1, 'xs-2': hasXs2}">
+        <div [ngClass]="{'xs-1': hasXs1, 'xs-3': hasXs3}" 
+             [ngClass.xs]="{'xs-1': hasXs1, 'xs-2': hasXs2}">
         </div>
     `);
     activateMediaQuery('xs');
@@ -105,6 +122,11 @@ describe('class directive', () => {
 
     expectNativeEl(fixture, {hasXs1: false, hasXs2: true}).toHaveCssClass('xs-2');
     expectNativeEl(fixture, {hasXs1: false, hasXs2: true}).not.toHaveCssClass('xs-1');
+
+    activateMediaQuery('md');
+    expectNativeEl(fixture, {hasXs1: true, hasX2: false, hasXs3: true}).toHaveCssClass('xs-3');
+    expectNativeEl(fixture, {hasXs1: true, hasX2: false, hasXs3: true}).not.toHaveCssClass('xs-2');
+    expectNativeEl(fixture, {hasXs1: true, hasX2: false, hasXs3: true}).toHaveCssClass('xs-1');
   });
 
   it('should work with ngClass array notation', () => {

src/lib/flexbox/api/class.ts

@@ -32,17 +32,28 @@ export type NgClassType = string | string[] | Set<string> | {[klass: string]: an
  */
 @Directive({
   selector: `
+    [class],
     [class.xs], [class.sm], [class.md], [class.lg], [class.xl], 
     [class.lt-sm], [class.lt-md], [class.lt-lg], [class.lt-xl],     
-    [class.gt-xs], [class.gt-sm], [class.gt-md], [class.gt-lg],
-        
+    [class.gt-xs], [class.gt-sm], [class.gt-md], [class.gt-lg],        
+    [ngClass], 
     [ngClass.xs], [ngClass.sm], [ngClass.md], [ngClass.lg], [ngClass.xl],
     [ngClass.lt-sm], [ngClass.lt-md], [ngClass.lt-lg], [ngClass.lt-xl], 
     [ngClass.gt-xs], [ngClass.gt-sm], [ngClass.gt-md], [ngClass.gt-lg]  
   `
 })
 export class ClassDirective extends NgClass implements OnInit, OnChanges, OnDestroy {
 
+  /**
+   * Intercept ngClass assignments so we cache the default classes
+   * which are merged with activated styles or used as fallbacks.
+   */
+  @Input('ngClass')
+  set ngClassBase(val: NgClassType) {
+    this._base.cacheInput('class', val, true);
+    this.ngClass = this._base.inputMap['class'];
+  }
+
   /* tslint:disable */
   @Input('ngClass.xs')    set ngClassXs(val: NgClassType) { this._base.cacheInput('classXs', val, true); }
   @Input('ngClass.sm')    set ngClassSm(val: NgClassType) {  this._base.cacheInput('classSm', val, true); };
@@ -61,6 +72,7 @@ export class ClassDirective extends NgClass implements OnInit, OnChanges, OnDest
   @Input('ngClass.gt-lg') set ngClassGtLg(val: NgClassType) { this._base.cacheInput('classGtLg', val, true); };
 
   /** Deprecated selectors */
+  @Input('class')         set classBase(val: NgClassType) { this._base.cacheInput('class', val, true); }
   @Input('class.xs')      set classXs(val: NgClassType) { this._base.cacheInput('classXs', val, true); }
   @Input('class.sm')      set classSm(val: NgClassType) {  this._base.cacheInput('classSm', val, true); };
   @Input('class.md')      set classMd(val: NgClassType) { this._base.cacheInput('classMd', val, true);};
@@ -94,7 +106,7 @@ export class ClassDirective extends NgClass implements OnInit, OnChanges, OnDest
       return (`ngClass${it.suffix}` in changes) || (`class${it.suffix}` in changes);
     });
     if (changed || this._base.mqActivation) {
-      this._updateStyle();
+      this._updateClass();
     }
   }
 
@@ -104,16 +116,16 @@ export class ClassDirective extends NgClass implements OnInit, OnChanges, OnDest
    */
   ngOnInit() {
     this._base.listenForMediaQueryChanges('class', '', (changes: MediaChange) => {
-      this._updateStyle(changes.value);
+      this._updateClass(changes.value);
     });
-    this._updateStyle();
+    this._updateClass();
   }
 
   ngOnDestroy() {
     this._base.ngOnDestroy();
   }
 
-  protected _updateStyle(value?: NgClassType) {
+  protected _updateClass(value?: NgClassType) {
     let clazz = value || this._base.queryInput("class") || '';
     if (this._base.mqActivation) {
       clazz = this._base.mqActivation.activatedInput;