feat(sketches): enable use of index inside factory function

Author: Gregor Woiwode

src/sketches.ts

@@ -1,6 +1,8 @@
 import { OverwritableSketch } from './overwritable-sketch';
 
-export declare type PartialFactory<T> = { [key in keyof T]?: () => T[key] };
+export declare type PartialFactory<T> = {
+  [key in keyof T]?: (index: number) => T[key]
+};
 
 export class Sketches<T> {
   constructor(private _sketches: Array<OverwritableSketch<T>>) {}
@@ -16,8 +18,8 @@ export class Sketches<T> {
 
   private _resolve(generators: PartialFactory<T>): Partial<T> {
     return Object.keys(generators)
-      .map(key => ({
-        [key]: (generators as any)[key]()
+      .map((key, index) => ({
+        [key]: (generators as any)[key](index)
       }))
       .reduce(
         (combinedOverrides, override) => ({

test/create-list-of-models.spec.ts

@@ -34,4 +34,17 @@ describe('When a list of test data is needed', () => {
 
     expect(models[0].id).toBe(id);
   });
+
+  it('should pass the index of the respective model', () => {
+    const id = '12-34-56-78-';
+    const expectedId = '12-34-56-78-0';
+
+    const models = Kentan.sketch(ForEmpty)
+      .take(1)
+      .models({
+        id: index => `${id}${index}`
+      });
+
+    expect(models[0].id).toBe(expectedId);
+  });
 });