feat: add index and array based overrides for createMany and makeMany

README.md

@@ -122,6 +122,15 @@ new UserFactory().make({ email: '[email protected]' })
 new UserFactory().makeMany(10, { email: '[email protected]' })
 ```
 
+When making many entities, the details on each instance can be fine-tuned using a callback or an array syntax:
+```ts
+// each second user will be created with disabled flag set
+new UserFactory().makeMany(10, [{ }, { disabled: true }])
+
+// each second user will be created with disabled flag set, using a function syntax. The result will be similar to the above.
+new UserFactory().makeMany(10, (index) => ({ disabled: Boolean(index % 2) }))
+```
+
 ## `create` & `createMany`
 
 the create and createMany method is similar to the make and makeMany method, but at the end the created entity instance gets persisted in the database using TypeORM entity manager.
@@ -145,6 +154,8 @@ new UserFactory().createMany(10, { email: '[email protected]' })
 // using save options
 new UserFactory().create({ email: '[email protected]' }, { listeners: false })
 new UserFactory().createMany(10, { email: '[email protected]' }, { listeners: false })
+new UserFactory().createMany(10, [{}, { disabled: true }])
+new UserFactory().createMany(10, (index) => ({ disabled: Boolean(index % 2) }))
 ```
 
 ## `attrs`

src/factory.ts

@@ -1,7 +1,7 @@
 import type { DataSource, SaveOptions } from "typeorm";
 import { EagerInstanceAttribute, LazyInstanceAttribute } from "./instanceAttributes";
 import { BaseSubfactory } from "./subfactories";
-import type { Constructable, FactorizedAttrs } from "./types";
+import type { Constructable, FactorizedAttrs, SequenceAttrs } from "./types";
 
 export abstract class Factory<T extends object> {
 	protected abstract entity: Constructable<T>;
@@ -25,10 +25,11 @@ export abstract class Factory<T extends object> {
 	/**
 	 * Make many new entities without persisting it
 	 */
-	async makeMany(amount: number, overrideParams: Partial<FactorizedAttrs<T>> = {}): Promise<T[]> {
+	async makeMany(amount: number, overrideParams: SequenceAttrs<T> = {}): Promise<T[]> {
 		const list = [];
 		for (let index = 0; index < amount; index++) {
-			list[index] = await this.make(overrideParams);
+			const attrs = await this.getAttrsFromSequence(index, overrideParams);
+			list[index] = await this.make(attrs);
 		}
 		return list;
 	}
@@ -53,14 +54,11 @@ export abstract class Factory<T extends object> {
 	/**
 	 * Create many new entities and persist them
 	 */
-	async createMany(
-		amount: number,
-		overrideParams: Partial<FactorizedAttrs<T>> = {},
-		saveOptions?: SaveOptions,
-	): Promise<T[]> {
+	async createMany(amount: number, overrideParams: SequenceAttrs<T> = {}, saveOptions?: SaveOptions): Promise<T[]> {
 		const list = [];
 		for (let index = 0; index < amount; index++) {
-			list[index] = await this.create(overrideParams, saveOptions);
+			const attrs = await this.getAttrsFromSequence(index, overrideParams);
+			list[index] = await this.create(attrs, saveOptions);
 		}
 		return list;
 	}
@@ -103,6 +101,12 @@ export abstract class Factory<T extends object> {
 		);
 	}
 
+	private async getAttrsFromSequence<T>(index: number, params: SequenceAttrs<T>): Promise<Partial<FactorizedAttrs<T>>> {
+		if (typeof params === "function") return params(index);
+		if (Array.isArray(params)) return params[index % params.length] ?? {};
+		return params;
+	}
+
 	private static async resolveValue(value: unknown, shouldPersist: boolean): Promise<unknown> {
 		if (value instanceof BaseSubfactory) {
 			return shouldPersist ? value.create() : value.make();

src/types.ts

@@ -18,3 +18,5 @@ export type InstanceAttributeCallback<T, V> = (entity: T) => FactorizedAttr<V>;
 // Helper types
 export type Constructable<T> = new () => T;
 export type IsObject<T> = T extends object ? T : never;
+export type GetChildAttrs<T> = (index: number) => Partial<FactorizedAttrs<T>>;
+export type SequenceAttrs<T> = GetChildAttrs<T> | Partial<FactorizedAttrs<T>> | Partial<FactorizedAttrs<T>>[];

test/factory.test.ts

@@ -167,6 +167,37 @@ describe(Factory, () => {
 				expect(entity.id).toBeUndefined();
 			}
 		});
+
+		test("Should make entities with array based overrideParams", async () => {
+			const count = 4;
+			const factory = new UserFactory();
+			const entitiesMaked = await factory.makeMany(count, [
+				{ email: "[email protected]" },
+				{ email: "[email protected]" },
+			]);
+
+			expect(entitiesMaked).toHaveLength(count);
+
+			for (let i = 0; i < count; i++) {
+				const entity = entitiesMaked[i] as User;
+				expect(entity.id).toBeUndefined();
+				expect(entity.email).toEqual(["[email protected]", "[email protected]"][i % 2]);
+			}
+		});
+
+		test("Should make entities with function based overrideParams", async () => {
+			const count = 4;
+			const factory = new UserFactory();
+			const entitiesMaked = await factory.makeMany(count, (index) => ({ email: `${index}@no-reply.bar` }));
+
+			expect(entitiesMaked).toHaveLength(count);
+
+			for (let i = 0; i < count; i++) {
+				const entity = entitiesMaked[i] as User;
+				expect(entity.id).toBeUndefined();
+				expect(entity.email).toEqual(`${i}@no-reply.bar`);
+			}
+		});
 	});
 
 	describe(Factory.prototype.create, () => {
@@ -324,5 +355,36 @@ describe(Factory, () => {
 				expect(entity.id).toBeDefined();
 			}
 		});
+
+		test("Should create entities with array based overrideParams", async () => {
+			const count = 4;
+			const factory = new UserFactory();
+			const entitiesCreated = await factory.createMany(count, [
+				{ email: "[email protected]" },
+				{ email: "[email protected]" },
+			]);
+
+			expect(entitiesCreated).toHaveLength(count);
+
+			for (let i = 0; i < count; i++) {
+				const entity = entitiesCreated[i] as User;
+				expect(entity.id).toBeDefined();
+				expect(entity.email).toEqual(["[email protected]", "[email protected]"][i % 2]);
+			}
+		});
+
+		test("Should create entities with function based overrideParams", async () => {
+			const count = 4;
+			const factory = new UserFactory();
+			const entitiesCreated = await factory.createMany(count, (index) => ({ email: `${index}@no-reply.bar` }));
+
+			expect(entitiesCreated).toHaveLength(count);
+
+			for (let i = 0; i < count; i++) {
+				const entity = entitiesCreated[i] as User;
+				expect(entity.id).toBeDefined();
+				expect(entity.email).toEqual(`${i}@no-reply.bar`);
+			}
+		});
 	});
 });