Implemented the distance donation response

ref #66

src/models/entities/DistanceDonation.ts

@@ -1,5 +1,6 @@
 import { IsInt, IsNotEmpty, IsPositive } from "class-validator";
 import { ChildEntity, Column, ManyToOne } from "typeorm";
+import { ResponseDistanceDonation } from '../responses/ResponseDistanceDonation';
 import { Donation } from "./Donation";
 import { Runner } from "./Runner";
 
@@ -31,7 +32,7 @@ export class DistanceDonation extends Donation {
    * Get's calculated from the runner's distance ran and the amount donated per kilometer.
    */
   public get amount(): number {
-    let calculatedAmount = -1;
+    let calculatedAmount = 0;
     try {
       calculatedAmount = this.amountPerDistance * (this.runner.distance / 1000);
     } catch (error) {
@@ -43,7 +44,7 @@ export class DistanceDonation extends Donation {
   /**
    * Turns this entity into it's response class.
    */
-  public toResponse(): DistanceDonation {
-    return null;
+  public toResponse(): ResponseDistanceDonation {
+    return new ResponseDistanceDonation(this);
   }
 }