Completed test:

ClientApp/src/app/app.module.ts

@@ -10,6 +10,7 @@ import { HomeComponent } from './components/home/home.component';
 import { CounterComponent } from './components/counter/counter.component';
 import { SanctionedEntitiesComponent } from './components/sanctioned-entities/sanctioned-entities.component';
 import { JumbotronCounterComponent } from './components/jumbotron-counter/jumbotron-counter.component';
+import { CreateSanctionedEntityComponent } from './components/create-sanctioned-entity/create-sanctioned-entity.component';
 
 
 @NgModule({
@@ -19,7 +20,8 @@ import { JumbotronCounterComponent } from './components/jumbotron-counter/jumbot
     HomeComponent,
     CounterComponent,
     SanctionedEntitiesComponent,
-    JumbotronCounterComponent
+    JumbotronCounterComponent,
+    CreateSanctionedEntityComponent
   ],
   imports: [
     BrowserModule.withServerTransition({ appId: 'ng-cli-universal' }),
@@ -29,6 +31,7 @@ import { JumbotronCounterComponent } from './components/jumbotron-counter/jumbot
       { path: '', component: HomeComponent, pathMatch: 'full' },
       { path: 'counter', component: CounterComponent },
       { path: 'sanctioned-entities', component: SanctionedEntitiesComponent },
+      { path: 'create-sanction-entity', component: CreateSanctionedEntityComponent }
     ])
   ],
   providers: [],

ClientApp/src/app/components/counter/counter.component.html

@@ -2,6 +2,6 @@ <h1>Counter</h1>
 
 <p>This is a simple example of an Angular component.</p>
 
-<p aria-live="polite">Current count: <strong>{{ currentCount }}</strong></p>
+<p aria-live="polite">Current count: <strong>{{ counter$ | async}}</strong></p>
 
 <button class="btn btn-primary" (click)="incrementCounter()">Increment</button>

ClientApp/src/app/components/counter/counter.component.ts

@@ -1,13 +1,21 @@
-import { Component } from '@angular/core';
+import { Component, Input, OnDestroy } from '@angular/core';
+import { BehaviorSubject, Observable } from 'rxjs';
+import { CounterService } from 'src/app/services/counter.service';
 
 @Component({
   selector: 'app-counter-component',
   templateUrl: './counter.component.html'
 })
 export class CounterComponent {
-  public currentCount = 0;
+  public counter$: Observable<number>;
+
+  @Input('minimalistMode') minimalistMode: boolean = false;
+
+  constructor(private counterService: CounterService) {  
+    this.counter$ = this.counterService.getCounter();
+  }
 
   public incrementCounter() {
-    this.currentCount++;
+    this.counterService.increaseCounter();
   }
 }

ClientApp/src/app/components/create-sanctioned-entity/create-sanctioned-entity.component.html

@@ -0,0 +1,31 @@
+<h1 id="formLabel">Create a sanction</h1>
+
+<form class="row g-2 p-3" (ngSubmit)="save(form)" #form="ngForm">
+    <div class="col-md-6">
+        <label for="entityName" class="form-label">Name</label>
+        <input [(ngModel)]="newEntity.name" class="form-control" name="entityName" required
+            #entityName="ngModel" [class.is-invalid]="entityName.invalid && entityName.dirty">
+
+            <div class="invalid-feedback">Please provide an entity name.</div>
+    </div>
+    <br>
+    <div class="col-md-6">
+        <label for="domicile" class="form-label">Domicile</label>
+        <input [(ngModel)]="newEntity.domicile" class="form-control" name="domicile" required
+            #domicile="ngModel" [class.is-invalid]="domicile.invalid && domicile.dirty">
+
+        <div class="invalid-feedback">Please provide a domicile.</div>
+    </div>
+    <br>
+    <div class="col-md-6 form-check form-switch">
+        <label for="entityStatus" class="form-label">Is Entity Accepted?</label>
+        <input [(ngModel)]="newEntity.accepted" type="checkbox" role="switch" name="entityStatus" class="form-control form-check-input"
+            #entityStatus="ngModel">
+    </div>
+    <br>
+    <div class="col-md-6">
+        <div *ngIf="serverError" class="alert alert-danger" role="alert">{{serverError}}</div>
+
+        <button [disabled]="form.invalid" type="submit" class="btn btn-primary m-1">Submit</button>
+    </div>
+</form>

ClientApp/src/app/components/create-sanctioned-entity/create-sanctioned-entity.component.ts

@@ -0,0 +1,41 @@
+import { Component } from '@angular/core';
+import { SanctionedEntity } from '../../models/sanctioned-entity';
+import { SanctionedEntitiesService } from '../../services/sanctioned-entities.service';
+import { NgForm } from '@angular/forms';
+import { Router } from '@angular/router';
+import { catchError, throwError } from 'rxjs';
+
+@Component({
+  selector: 'app-sanctioned-entities',
+  templateUrl: './create-sanctioned-entity.component.html'
+})
+export class CreateSanctionedEntityComponent {
+  public newEntity: SanctionedEntity;
+  public serverError: string|null = null;
+
+  constructor(private entitiesService: SanctionedEntitiesService, private router: Router) {
+    this.newEntity = { id: '', accepted: false, domicile: '', name: ''};
+  }
+
+  public save(form: NgForm): void {
+
+    if(form.valid && form.enabled){
+      this.entitiesService.createNewEntity(this.newEntity)
+      .pipe(
+        catchError(response => {
+          this.serverError = response.error.detail;
+
+          return throwError(response);
+        })
+      )
+      .subscribe(newEntity => {
+
+        if(newEntity){
+          this.router.navigate(['/sanctioned-entities']);
+        }
+
+      });
+    }
+  }
+
+}

ClientApp/src/app/components/jumbotron-counter/jumbotron-counter.component.html

@@ -1,4 +1,15 @@
 <div class="jumbotron text-center">
     <p>Current count:</p>
-    <p><strong>Please include the counter here</strong></p>
+    <p><strong>{{ counter$ | async}}</strong></p>
+
+    <!-- <p><strong>Please include the counter here</strong></p> -->
+
+    <!-- 
+        NOTE: I have interpreted "Please include the counter here" as just including the counted number here,
+       but could've also been interpreted as include the whole component here in some form,
+       with maybe an input to turn off parts of the UI like the title in a more minimalist mode like below commented out
+       Wouldn't leave this comment here, would normally be a discussion on user story or during refinement meetings etc.
+       -->
+
+    <!-- <app-counter-component [minimalistMode]="true"></app-counter-component> -->
 </div>

ClientApp/src/app/components/jumbotron-counter/jumbotron-counter.component.ts

@@ -1,8 +1,16 @@
 import { Component } from '@angular/core';
+import { BehaviorSubject, Observable } from 'rxjs';
+import { CounterService } from 'src/app/services/counter.service';
 
 @Component({
   selector: 'app-jumbotron-counter',
   templateUrl: './jumbotron-counter.component.html'
 })
 export class JumbotronCounterComponent {
+  public counter$: Observable<number>;
+
+  constructor(private counterService: CounterService){
+    this.counter$ = this.counterService.getCounter();
+  }
+
 }

ClientApp/src/app/components/sanctioned-entities/sanctioned-entities.component.html

@@ -1,7 +1,9 @@
 <h1 id="tableLabel">Sanctioned Entities</h1>
+<button class="btn btn-primary" [routerLink]="['/create-sanction-entity']">Create Sanction</button>
 
 <p *ngIf="!entities"><em>Loading...</em></p>
 
+
 <table class='table table-striped' aria-labelledby="tableLabel" *ngIf="entities">
     <thead>
     <tr>

ClientApp/src/app/components/sanctioned-entities/sanctioned-entities.component.ts

@@ -14,4 +14,5 @@ export class SanctionedEntitiesComponent {
       this.entities = entities;
     });
   }
+
 }

ClientApp/src/app/services/counter.service.ts

@@ -0,0 +1,23 @@
+import { Injectable } from '@angular/core';
+import { BehaviorSubject, Observable } from 'rxjs';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class CounterService {
+
+  private counterSubject: BehaviorSubject<number> = new BehaviorSubject(0);
+  private counter$ = this.counterSubject.asObservable();
+
+  constructor() {
+
+  }
+
+  public getCounter(): Observable<number> {
+    return this.counter$;
+  }
+
+  public increaseCounter() : void{
+    this.counterSubject.next(this.counterSubject.value + 1);
+  }
+}

ClientApp/src/app/services/sanctioned-entities.service.ts

@@ -19,4 +19,10 @@ export class SanctionedEntitiesService {
     const url = this.apiUrl + this.path;
     return this.http.get<SanctionedEntity[]>(url);
   }
+
+  public createNewEntity(newEntity: SanctionedEntity): Observable<boolean> {
+    const url = this.apiUrl + this.path;
+
+    return this.http.post<boolean>(url, newEntity);
+  }
 }

Controllers/SanctionedEntitiesController.cs

@@ -1,4 +1,5 @@
-using ajgre_technical_interview.Services;
+using ajgre_technical_interview.Models;
+using ajgre_technical_interview.Services;
 using Microsoft.AspNetCore.Mvc;
 
 namespace ajgre_technical_interview.Controllers
@@ -8,10 +9,12 @@ namespace ajgre_technical_interview.Controllers
     public class SanctionedEntitiesController : ControllerBase
     {
         private readonly IDatabaseService _databaseService;
+        private readonly ILogger<SanctionedEntitiesController> _logger;
 
-        public SanctionedEntitiesController(IDatabaseService databaseService)
+        public SanctionedEntitiesController(IDatabaseService databaseService, ILogger<SanctionedEntitiesController> logger)
         {
             _databaseService = databaseService;
+            _logger = logger;
         }
 
 
@@ -25,9 +28,27 @@ public async Task<IActionResult> GetSanctionedEntities()
             }
             catch (Exception ex)
             {
+                //A little logging is always nice to have!
+                _logger.LogError(ex, $"Exception occured in route '{nameof(GetSanctionedEntities)}'");
                 return Problem(ex.Message);
             }
 
         }
+
+        [HttpPost]
+        public async Task<IActionResult> CreateSanctionEntity([FromBody] SanctionedEntity newSanctionEntity)
+        {
+            try
+            {
+                var newEntity = await _databaseService.CreateSanctionedEntityAsync(newSanctionEntity);
+                return Ok(newEntity);
+            }
+            catch (Exception ex)
+            {
+                //A little logging is always nice to have!
+                _logger.LogError(ex, $"Exception occured in route '{nameof(CreateSanctionEntity)}'");
+                return Problem(ex.Message);
+            }
+        }
     }
 }

Services/DatabaseService.cs

@@ -29,6 +29,16 @@ public async Task<SanctionedEntity> GetSanctionedEntityByIdAsync(Guid id)
 
         public async Task<SanctionedEntity> CreateSanctionedEntityAsync(SanctionedEntity sanctionedEntity)
         {
+            //Validate that there is not a sanctioned entity with the same name and domicile already.
+            //Would normally seperate this validation into a step in a service sitting between DB and the controller.
+            var newEntityIsValid = !SanctionedEntities.Any(x => x.Name == sanctionedEntity.Name 
+                                                                && x.Domicile == sanctionedEntity.Domicile);
+
+            if (!newEntityIsValid)
+            {
+                throw new Exception("A sanctioned entity with the same name and domicile already exists.");
+            }
+
             SanctionedEntities.Add(sanctionedEntity);
             return await Task.FromResult(sanctionedEntity);
         }