fix(select): consistent error behavior to md-input-container

* Gets `md-select` to behave in the same way as `md-input-container` when it comes to errors. This means highlighting itself when it is invalid and touched, or one of the parent forms/form groups is submitted.
* Moves the error state logic into a separate function in order to avoid some hard-to-follow selectors and to potentially allow overrides. This should also be a first step to supporting `md-error` inside `md-select`.
* Changes the required asterisk to always have the theme warn color, similarly to the input asterisk.

Fixes #4611.

src/lib/select/_select-theme.scss

@@ -66,8 +66,7 @@
     }
   }
 
-  .mat-select:focus:not(.mat-select-disabled).mat-warn,
-  .mat-select:not(:focus).ng-invalid.ng-touched:not(.mat-select-disabled) {
+  .mat-select:focus:not(.mat-select-disabled).mat-warn, .mat-select-invalid {
     @include _mat-select-inner-content-theme($warn);
   }
 }

src/lib/select/select.spec.ts

@@ -1,5 +1,3 @@
-import {TestBed, async, ComponentFixture, fakeAsync, tick, inject} from '@angular/core/testing';
-import {By} from '@angular/platform-browser';
 import {
   Component,
   DebugElement,
@@ -9,17 +7,26 @@ import {
   ChangeDetectionStrategy,
   OnInit,
 } from '@angular/core';
+import {
+  ControlValueAccessor,
+  FormControl,
+  FormsModule,
+  NG_VALUE_ACCESSOR,
+  ReactiveFormsModule,
+  FormGroup,
+  FormGroupDirective,
+  Validators,
+} from '@angular/forms';
+import {By} from '@angular/platform-browser';
 import {NoopAnimationsModule} from '@angular/platform-browser/animations';
+import {TestBed, async, ComponentFixture, fakeAsync, tick, inject} from '@angular/core/testing';
 import {MdSelectModule} from './index';
 import {OverlayContainer} from '../core/overlay/overlay-container';
 import {MdSelect} from './select';
 import {getMdSelectDynamicMultipleError, getMdSelectNonArrayValueError} from './select-errors';
 import {MdOption} from '../core/option/option';
 import {Directionality} from '../core/bidi/index';
 import {DOWN_ARROW, UP_ARROW, ENTER, SPACE, HOME, END, TAB} from '../core/keyboard/keycodes';
-import {
-  ControlValueAccessor, FormControl, FormsModule, NG_VALUE_ACCESSOR, ReactiveFormsModule
-} from '@angular/forms';
 import {Subject} from 'rxjs/Subject';
 import {ViewportRuler} from '../core/overlay/position/viewport-ruler';
 import {dispatchFakeEvent, dispatchKeyboardEvent, wrappedErrorMessage} from '@angular/cdk/testing';
@@ -66,7 +73,8 @@ describe('MdSelect', () => {
         InvalidSelectInForm,
         BasicSelectWithoutForms,
         BasicSelectWithoutFormsPreselected,
-        BasicSelectWithoutFormsMultiple
+        BasicSelectWithoutFormsMultiple,
+        SelectInsideFormGroup
       ],
       providers: [
         {provide: OverlayContainer, useFactory: () => {
@@ -1719,11 +1727,12 @@ describe('MdSelect', () => {
           'mat-select-required', `Expected the mat-select-required class to be set.`);
       });
 
-      it('should set aria-invalid for selects that are invalid', () => {
+      it('should set aria-invalid for selects that are invalid and touched', () => {
         expect(select.getAttribute('aria-invalid'))
           .toEqual('false', `Expected aria-invalid attr to be false for valid selects.`);
 
         fixture.componentInstance.isRequired = true;
+        fixture.componentInstance.control.markAsTouched();
         fixture.detectChanges();
 
         expect(select.getAttribute('aria-invalid'))
@@ -2571,6 +2580,77 @@ describe('MdSelect', () => {
 
   });
 
+  describe('error state', () => {
+    let fixture: ComponentFixture<SelectInsideFormGroup>;
+    let testComponent: SelectInsideFormGroup;
+    let select: HTMLElement;
+
+    beforeEach(() => {
+      fixture = TestBed.createComponent(SelectInsideFormGroup);
+      fixture.detectChanges();
+      testComponent = fixture.componentInstance;
+      select = fixture.debugElement.query(By.css('md-select')).nativeElement;
+    });
+
+    it('should not set the invalid class on a clean select', () => {
+      expect(testComponent.formGroup.untouched).toBe(true, 'Expected the form to be untouched.');
+      expect(testComponent.formControl.invalid).toBe(true, 'Expected form control to be invalid.');
+      expect(select.classList)
+          .not.toContain('mat-select-invalid', 'Expected select not to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('false', 'Expected aria-invalid to be set to false.');
+    });
+
+    it('should appear as invalid if it becomes touched', () => {
+      expect(select.classList)
+          .not.toContain('mat-select-invalid', 'Expected select not to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('false', 'Expected aria-invalid to be set to false.');
+
+      testComponent.formControl.markAsTouched();
+      fixture.detectChanges();
+
+      expect(select.classList)
+          .toContain('mat-select-invalid', 'Expected select to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('true', 'Expected aria-invalid to be set to true.');
+    });
+
+    it('should not have the invalid class when the select becomes valid', () => {
+      testComponent.formControl.markAsTouched();
+      fixture.detectChanges();
+
+      expect(select.classList)
+          .toContain('mat-select-invalid', 'Expected select to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('true', 'Expected aria-invalid to be set to true.');
+
+      testComponent.formControl.setValue('pizza-1');
+      fixture.detectChanges();
+
+      expect(select.classList)
+          .not.toContain('mat-select-invalid', 'Expected select not to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('false', 'Expected aria-invalid to be set to false.');
+    });
+
+    it('should appear as invalid when the parent form group is submitted', () => {
+      expect(select.classList)
+          .not.toContain('mat-select-invalid', 'Expected select not to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('false', 'Expected aria-invalid to be set to false.');
+
+      dispatchFakeEvent(fixture.debugElement.query(By.css('form')).nativeElement, 'submit');
+      fixture.detectChanges();
+
+      expect(select.classList)
+          .toContain('mat-select-invalid', 'Expected select to appear invalid.');
+      expect(select.getAttribute('aria-invalid'))
+          .toBe('true', 'Expected aria-invalid to be set to true.');
+    });
+
+  });
+
 });
 
 
@@ -2918,6 +2998,7 @@ class BasicSelectWithTheming {
   theme: string;
 }
 
+
 @Component({
   selector: 'reset-values-select',
   template: `
@@ -2944,7 +3025,6 @@ class ResetValuesSelect {
   @ViewChild(MdSelect) select: MdSelect;
 }
 
-
 @Component({
   template: `
     <md-select [formControl]="control">
@@ -3028,6 +3108,25 @@ class InvalidSelectInForm {
 }
 
 
+@Component({
+  template: `
+    <form [formGroup]="formGroup">
+      <md-select placeholder="Food" formControlName="food">
+        <md-option value="steak-0">Steak</md-option>
+        <md-option value="pizza-1">Pizza</md-option>
+      </md-select>
+    </form>
+  `
+})
+class SelectInsideFormGroup {
+  @ViewChild(FormGroupDirective) formGroupDirective: FormGroupDirective;
+  formControl = new FormControl('', Validators.required);
+  formGroup = new FormGroup({
+    food: this.formControl
+  });
+}
+
+
 @Component({
   template: `
     <md-select placeholder="Food" [(value)]="selectedFood">

src/lib/select/select.ts

@@ -28,6 +28,7 @@ import {
   ChangeDetectionStrategy,
   InjectionToken,
 } from '@angular/core';
+import {NgForm, FormGroupDirective} from '@angular/forms';
 import {MdOption, MdOptionSelectionChange, MdOptgroup} from '../core/option/index';
 import {ENTER, SPACE, UP_ARROW, DOWN_ARROW, HOME, END} from '../core/keyboard/keycodes';
 import {FocusKeyManager} from '../core/a11y/focus-key-manager';
@@ -153,9 +154,10 @@ export const _MdSelectMixinBase = mixinColor(mixinDisabled(MdSelectBase), 'prima
     '[attr.aria-labelledby]': 'ariaLabelledby',
     '[attr.aria-required]': 'required.toString()',
     '[attr.aria-disabled]': 'disabled.toString()',
-    '[attr.aria-invalid]': '_control?.invalid || "false"',
+    '[attr.aria-invalid]': '_isErrorState()',
     '[attr.aria-owns]': '_optionIds',
     '[class.mat-select-disabled]': 'disabled',
+    '[class.mat-select-invalid]': '_isErrorState()',
     '[class.mat-select-required]': 'required',
     'class': 'mat-select',
     '(keydown)': '_handleClosedKeydown($event)',
@@ -368,10 +370,13 @@ export class MdSelect extends _MdSelectMixinBase implements AfterContentInit, On
     renderer: Renderer2,
     elementRef: ElementRef,
     @Optional() private _dir: Directionality,
+    @Optional() private _parentForm: NgForm,
+    @Optional() private _parentFormGroup: FormGroupDirective,
     @Self() @Optional() public _control: NgControl,
     @Attribute('tabindex') tabIndex: string,
     @Optional() @Inject(MD_PLACEHOLDER_GLOBAL_OPTIONS) placeholderOptions: PlaceholderOptions,
     @Inject(MD_SELECT_SCROLL_STRATEGY) private _scrollStrategyFactory) {
+
     super(renderer, elementRef);
 
     if (this._control) {
@@ -605,6 +610,16 @@ export class MdSelect extends _MdSelectMixinBase implements AfterContentInit, On
     return this._selectionModel && this._selectionModel.hasValue();
   }
 
+  /** Whether the select is in an error state. */
+  _isErrorState(): boolean {
+    const isInvalid = this._control && this._control.invalid;
+    const isTouched = this._control && this._control.touched;
+    const isSubmitted = (this._parentFormGroup && this._parentFormGroup.submitted) ||
+        (this._parentForm && this._parentForm.submitted);
+
+    return !!(isInvalid && (isTouched || isSubmitted));
+  }
+
   /**
    * Sets the scroll position of the scroll container. This must be called after
    * the overlay pane is attached or the scroll container element will not yet be