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 angular#4611.

src/lib/select/_select-theme.scss

@@ -51,10 +51,13 @@
     &.mat-accent {
       @include _mat-select-inner-content-theme($accent);
     }
+
+    .mat-select-placeholder::after {
+      color: mat-color($warn);
+    }
   }
 
-  .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 +7,27 @@ import {
   ChangeDetectionStrategy,
   OnInit,
 } from '@angular/core';
+import {
+  ControlValueAccessor,
+  FormControl,
+  FormsModule,
+  NG_VALUE_ACCESSOR,
+  ReactiveFormsModule,
+  FormGroup,
+  FormGroupDirective,
+  NgForm,
+  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, MdSelectFloatPlaceholderType} from './select';
 import {getMdSelectDynamicMultipleError, getMdSelectNonArrayValueError} from './select-errors';
 import {MdOption} from '../core/option/option';
 import {Dir} from '../core/rtl/dir';
 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} from '../core/testing/dispatch-events';
@@ -55,7 +63,8 @@ describe('MdSelect', () => {
         SelectEarlyAccessSibling,
         BasicSelectInitiallyHidden,
         BasicSelectNoPlaceholder,
-        BasicSelectWithTheming
+        BasicSelectWithTheming,
+        SelectInsideFormGroup
       ],
       providers: [
         {provide: OverlayContainer, useFactory: () => {
@@ -1341,11 +1350,12 @@ describe('MdSelect', () => {
           .toEqual('true', `Expected aria-required attr to be true for required selects.`);
       });
 
-      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'))
@@ -2022,6 +2032,77 @@ 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.');
+    });
+
+  });
+
 });
 
 
@@ -2366,3 +2447,21 @@ class BasicSelectWithTheming {
   @ViewChild(MdSelect) select: MdSelect;
   theme: string;
 }
+
+@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
+  });
+}

src/lib/select/select.ts

@@ -17,6 +17,7 @@ import {
   Attribute,
   OnInit,
 } from '@angular/core';
+import {NgForm, FormGroupDirective} from '@angular/forms';
 import {MdOption, MdOptionSelectionChange} from '../core/option/option';
 import {ENTER, SPACE, UP_ARROW, DOWN_ARROW, HOME, END} from '../core/keyboard/keycodes';
 import {FocusKeyManager} from '../core/a11y/focus-key-manager';
@@ -108,9 +109,10 @@ export type MdSelectFloatPlaceholderType = 'always' | 'never' | 'auto';
     '[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]': 'true',
     '(keydown)': '_handleClosedKeydown($event)',
     '(blur)': '_onBlur()',
@@ -313,7 +315,8 @@ export class MdSelect implements AfterContentInit, OnDestroy, OnInit, ControlVal
   constructor(private _element: ElementRef, private _renderer: Renderer2,
               private _viewportRuler: ViewportRuler, private _changeDetectorRef: ChangeDetectorRef,
               @Optional() private _dir: Dir, @Self() @Optional() public _control: NgControl,
-              @Attribute('tabindex') tabIndex: string) {
+              @Attribute('tabindex') tabIndex: string, @Optional() private _parentForm: NgForm,
+              @Optional() private _parentFormGroup: FormGroupDirective) {
 
     if (this._control) {
       this._control.valueAccessor = this;
@@ -533,6 +536,16 @@ export class MdSelect implements AfterContentInit, OnDestroy, OnInit, ControlVal
     this._setScrollTop();
   }
 
+  /** 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