Move custom step validation function so that users can simply import and use

Author: jwshinjwshin

src/cdk/stepper/stepper.ts

@@ -65,11 +65,7 @@ export class CdkStep {
   private _disabled = false;
 
   /** Whether user has seen the expanded step content or not . */
-  get interacted() { return this._interacted; }
-  set interacted(value: boolean) {
-    this._interacted = value;
-  }
-  private _interacted = false;
+  interacted = false;
 
   /** Label of the step. */
   @Input()

src/demo-app/stepper/stepper-demo.ts

@@ -1,7 +1,6 @@
 import {Component} from '@angular/core';
-import {
-  Validators, FormBuilder, FormGroup, FormArray, ValidationErrors, ValidatorFn
-} from '@angular/forms';
+import {Validators, FormBuilder, FormGroup} from '@angular/forms';
+import {stepValidator} from '@angular/material';
 
 @Component({
   moduleId: module.id,
@@ -34,20 +33,7 @@ export class StepperDemo {
         this._formBuilder.group({
           phoneFormCtrl: [''],
         })
-      ], this._stepValidator)
+      ], stepValidator)
     });
   }
-
-  /**
-   * Form array validator to check if all form groups in form array are valid.
-   * If not, it will return the index of the first invalid form group.
-   */
-  private _stepValidator: ValidatorFn = (formArray: FormArray): ValidationErrors | null => {
-    for (let i = 0; i < formArray.length; i++) {
-      if (formArray.at(i).invalid) {
-        return {'invalid step': {'index': i}};
-      }
-    }
-    return null;
-  }
 }

src/lib/stepper/stepper.ts

@@ -28,7 +28,28 @@ import {
   MD_ERROR_GLOBAL_OPTIONS,
   ErrorStateMatcher
 } from '../core/error/error-options';
-import {FormControl, FormGroupDirective, NgForm} from '@angular/forms';
+import {
+  FormArray, FormControl, FormGroupDirective, NgForm, ValidationErrors,
+  ValidatorFn
+} from '@angular/forms';
+
+/**
+ * Form array validator to check if all form groups in form array are valid.
+ * If not, it will return the index of the first invalid form group.
+ */
+export const stepValidator: ValidatorFn = (formArray: FormArray): ValidationErrors | null => {
+  for (let i = 0; i < formArray.length; i++) {
+    if (formArray.at(i).invalid) {
+      return {'invalid step': {'index': i}};
+    }
+  }
+  return null;
+};
+
+/**
+ * Form array validator to check if all form groups in form array are valid.
+ * If not, it will return the index of the first invalid form group.
+ */
 
 @Component({
   moduleId: module.id,