feat(facade/collections): add own Object.assign ponyfill

src/facade/collections.ts

@@ -208,6 +208,37 @@ export class StringMapWrapper {
     return true;
   }
 
+  static assign<T,S>( target: T, ...sources: S[] ): T&S {
+
+    if ( !isPresent( target ) ) {
+      throw new TypeError( 'Object.assign cannot be called with null or undefined' );
+    }
+
+    const hasOwnProperty = Object.prototype.hasOwnProperty;
+
+    if ( (Object as any).assign ) {
+      return (Object as any).assign( target, ...sources );
+    }
+
+    let from;
+    const to = Object( target );
+
+    for ( var s = 0; s < sources.length; s++ ) {
+
+      from = Object( sources[ s ] );
+
+      for ( var key in from ) {
+        if ( hasOwnProperty.call( from, key ) ) {
+          to[ key ] = from[ key ];
+        }
+      }
+
+    }
+
+    return to;
+
+  }
+
 }
 
 

test/facade/collections.spec.ts

@@ -110,6 +110,45 @@ describe( `facade/collections`, ()=> {
 
     } );
 
+    describe( `#assign`, ()=> {
+
+      it( `should combine objects by extend`, ()=> {
+
+        const mutatedObj = {one:1};
+        const sourceOne = {two:2};
+        let actual = StringMapWrapper.assign( mutatedObj, sourceOne, { one: '111' } as any );
+        let expected = { one: '111', two: 2 };
+
+        expect(actual).to.deep.equal(expected);
+        expect( mutatedObj ).to.deep.equal( expected );
+        expect( sourceOne ).to.deep.equal( sourceOne );
+
+        const actual2 = StringMapWrapper.assign( {}, { foo: 'fooo', bar: 'baz' }, { twoo: 'phar' } as any );
+        const expected2 = { foo: 'fooo', bar: 'baz', twoo: 'phar' };
+        expect( actual2 ).to.deep.equal( expected2 );
+
+      } );
+
+      it( `should work as expected if Object.assign is not available`, ()=> {
+
+        const envAssign = (Object as any).assign;
+        (Object as any).assign = undefined;
+
+        const mutatedObj = {one:1};
+        const sourceOne = {two:2};
+        let actual = StringMapWrapper.assign( mutatedObj, sourceOne, { one: '111' } as any );
+        let expected = { one: '111', two: 2 };
+
+        expect(actual).to.deep.equal(expected);
+        expect( mutatedObj ).to.deep.equal( expected );
+        expect( sourceOne ).to.deep.equal( sourceOne );
+
+        (Object as any).assign = envAssign;
+
+      } );
+
+    } );
+
   } );
 
   describe( `ListWrapper`, ()=> {