[CST-4634] Added custom validator and messages and show error message for not valid email, lint fixes & unit testing

src/app/access-control/access-control.module.ts

@@ -10,6 +10,7 @@ import { MembersListComponent } from './group-registry/group-form/members-list/m
 import { SubgroupsListComponent } from './group-registry/group-form/subgroup-list/subgroups-list.component';
 import { GroupsRegistryComponent } from './group-registry/groups-registry.component';
 
+
 @NgModule({
   imports: [
     CommonModule,

src/app/access-control/epeople-registry/eperson-form/eperson-form.component.ts

@@ -1,5 +1,5 @@
 import { Component, EventEmitter, OnDestroy, OnInit, Output } from '@angular/core';
-import { FormGroup } from '@angular/forms';
+import { FormGroup, Validators } from '@angular/forms';
 import {
   DynamicCheckboxModel,
   DynamicFormControlModel,
@@ -33,6 +33,7 @@ import { RequestService } from '../../../core/data/request.service';
 import { NoContent } from '../../../core/shared/NoContent.model';
 import { PaginationService } from '../../../core/pagination/pagination.service';
 import { followLink } from '../../../shared/utils/follow-link-config.model';
+import { ValidateEmailNotTaken } from './validators/email-taken.validator';
 
 @Component({
   selector: 'ds-eperson-form',
@@ -187,6 +188,7 @@ export class EPersonFormComponent implements OnInit, OnDestroy {
    * This method will initialise the page
    */
   initialisePage() {
+
     observableCombineLatest(
       this.translateService.get(`${this.messagePrefix}.firstName`),
       this.translateService.get(`${this.messagePrefix}.lastName`),
@@ -219,9 +221,13 @@ export class EPersonFormComponent implements OnInit, OnDestroy {
         name: 'email',
         validators: {
           required: null,
-          pattern: '^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[a-z]{2,4}$'
+          pattern: '^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[a-z]{2,4}$',
         },
         required: true,
+        errorMessages: {
+            emailTaken: 'error.validation.emailTaken',
+            pattern: 'error.validation.NotValidEmail'
+        },
         hint: emailHint
       });
       this.canLogIn = new DynamicCheckboxModel(
@@ -262,6 +268,10 @@ export class EPersonFormComponent implements OnInit, OnDestroy {
         });
       }));
 
+      if (!!this.formGroup.controls.email) {
+        this.formGroup.controls.email.setAsyncValidators(ValidateEmailNotTaken.createValidator(this.epersonService));
+      }
+
       const activeEPerson$ = this.epersonService.getActiveEPerson();
 
       this.groups  = activeEPerson$.pipe(

src/app/access-control/epeople-registry/eperson-form/validators/email-taken.validator.ts

@@ -0,0 +1,23 @@
+import { AbstractControl, ValidationErrors } from '@angular/forms';
+import { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+
+import { EPersonDataService } from '../../../../core/eperson/eperson-data.service';
+import { getFirstSucceededRemoteData, } from '../../../../core/shared/operators';
+
+export class ValidateEmailNotTaken {
+
+  /**
+   * This method will create the validator with the ePersonDataService requested from component
+   * @param ePersonDataService the service with DI in the component that this validator is being utilized.
+   */
+    static createValidator(ePersonDataService: EPersonDataService) {
+        return (control: AbstractControl): Promise<ValidationErrors | null> | Observable<ValidationErrors | null>  => {
+            return ePersonDataService.getEPersonByEmail(control.value)
+                    .pipe(
+                        getFirstSucceededRemoteData(),
+                        map(res => { return !!res.payload ? { emailTaken: true } : null; })
+                    );
+        };
+    }
+}

src/assets/i18n/en.json5

@@ -1260,6 +1260,11 @@
 
   "error.validation.filerequired": "The file upload is mandatory",
 
+  "error.validation.required": "This field is required",
+
+  "error.validation.NotValidEmail": "This E-mail is not a valid email",
+
+  "error.validation.emailTaken": "This E-mail is already taken",
 
 
   "file-section.error.header": "Error obtaining files for this item",