test(select): fix silent error being logged

Fixes a select test that occasionally fails to capture the error inside the expect, causing it to get logged without actually being thrown. This seems to be a Zone-related issue since wrapping a few calls in `async` makes it behave correctly.

Author: crisbeto

src/lib/select/select.spec.ts

@@ -1450,13 +1450,13 @@ describe('MdSelect', () => {
     let testInstance: MultiSelect;
     let trigger: HTMLElement;
 
-    beforeEach(() => {
+    beforeEach(async(() => {
       fixture = TestBed.createComponent(MultiSelect);
       testInstance = fixture.componentInstance;
       fixture.detectChanges();
 
       trigger = fixture.debugElement.query(By.css('.mat-select-trigger')).nativeElement;
-    });
+    }));
 
     it('should be able to select multiple values', () => {
       trigger.click();
@@ -1616,17 +1616,17 @@ describe('MdSelect', () => {
       expect(trigger.textContent).toContain('Tacos, Pizza, Steak');
     });
 
-    it('should throw an exception when trying to set a non-array value', () => {
+    it('should throw an exception when trying to set a non-array value', async(() => {
       expect(() => {
         testInstance.control.setValue('not-an-array');
       }).toThrowError(wrappedErrorMessage(new MdSelectNonArrayValueError()));
-    });
+    }));
 
-    it('should throw an exception when trying to change multiple mode after init', () => {
+    it('should throw an exception when trying to change multiple mode after init', async(() => {
       expect(() => {
         testInstance.select.multiple = false;
       }).toThrowError(wrappedErrorMessage(new MdSelectDynamicMultipleError()));
-    });
+    }));
 
     it('should pass the `multiple` value to all of the option instances', async(() => {
       trigger.click();