@anatine/zod-mock

Generates a mock data object using faker.js from a Zod schema.

----

Installation

@faker-js/faker is a peer dependency of @anatine/zod-mock and is used for mock data generation.

``shell
npm install zod @faker-js/faker @anatine/zod-mock
`

----

Usage

$3

`typescript
import { generateMock } from '@anatine/zod-mock';
const schema = z.object({
uid: z.string().nonempty(),
theme: z.enum([light, dark]),
email: z.string().email().optional(),
phoneNumber: z.string().min(10).optional(),
avatar: z.string().url().optional(),
jobTitle: z.string().optional(),
otherUserEmails: z.array(z.string().email()),
stringArrays: z.array(z.string()),
stringLength: z.string().transform((val) => val.length),
numberCount: z.number().transform((item) => total value = ${item}),
age: z.number().min(18).max(120),
});
const mockData = generateMock(schema);
// ...
`

This will generate mock data similar to:

`json
{
"uid": "3f46b40e-95ed-43d0-9165-0b8730de8d14",
"theme": "light",
"email": "Alexandre99@hotmail.com",
"phoneNumber": "1-665-405-2226",
"avatar": "https://cdn.fakercloud.com/avatars/olaolusoga_128.jpg",
"jobTitle": "Lead Brand Facilitator",
"otherUserEmails": [
"Wyman58@example.net",
"Ignacio_Nader@example.org",
"Jorge_Bradtke@example.org",
"Elena.Torphy33@example.org",
"Kelli_Bartoletti@example.com"
],
"stringArrays": [
"quisquam",
"corrupti",
"atque",
"sunt",
"voluptatem"
],
"stringLength": 4,
"numberCount": "total value = 25430",
"age": 110
}
`

----

Overriding string mocks

Sometimes there might be a reason to have a more specific mock for a string value.

You can supply an options field to generate specific mock data that will be triggered by the matching key.

`typescript
const schema = z.object({
locked: z.string(),
email: z.string().email(),
primaryColor: z.string(),
});
const mockData = generateMock(schema, {
stringMap: {
locked: () => this return set to the locked value,
email: () => not a email anymore,
primaryColor: () => faker.internet.color(),
},
});
`

----

Adding a seed generator

For consistent testing, you can also add in a seed or seed array.

`typescript
const schema = z.object({
name: z.string(),
age: z.number(),
});
const seed = 123;
const first = generateMock(schema, { seed });
const second = generateMock(schema, { seed });
expect(first).toEqual(second);
`

----

Adding a custom mock mapper

Once drilled down to deliver a string, number, boolean, or other primitive value a function with a matching name is searched for in faker.

You can add your own key/fn mapper in the options.

`typescript

export function mockeryMapper(
keyName: string,
fakerInstance: Faker
): FakerFunction | undefined {
const keyToFnMap: Record = {
image: fakerInstance.image.url,
imageurl: fakerInstance.image.url,
number: fakerInstance.number.int,
float: fakerInstance.number.float,
hexadecimal: fakerInstance.number.hex,
uuid: fakerInstance.string.uuid,
boolean: fakerInstance.datatype.boolean,
// Email more guaranteed to be random for testing
email: () => fakerInstance.database.mongodbObjectId() + '@example.com'
};
return keyName && keyName.toLowerCase() in keyToFnMap
? keyToFnMap[keyName.toLowerCase() as never]
: undefined;
}

const schema = z.object({
locked: z.string(),
email: z.string().email(),
primaryColor: z.string(),
});

const result = generateMock(schema, { mockeryMapper });

`

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Behind the Scenes

zod-mock tries to generate mock data from two sources.

- ### Object key name ie({ firstName: z.string() })

This will check the string name of the key against all the available faker function names.
Upon a match, it uses that function to generate a mock value.

- ### Zodtype ie(const something = z.string())

In the case there is no key name (the schema doesn't contain an object) or there is no key name match,
zod-mock will use the primitive type provided by zod.

Some zod filter types (email, uuid, url, min, max, length) will also modify the results.

If zod-mock does not yet support a Zod type used in your schema, you may provide a backup mock function to use for that particular type.

` typescript
const schema = z.object({
anyVal: z.any()
});
const mockData = generateMock(schema, {
backupMocks: {
ZodAny: () => 'a value'
}
});
`

----

Missing Features

- No pattern for passing options into faker`, such as setting phone number formatting
- Does not handle the following Zod types:
- ZodAny
- ZodDefault
- ZodFunction
- ZodIntersection
- ZodMap
- ZodPromise
- ZodSet
- ZodTuple
- ZodUnion
- ZodUnknown

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Credits

- ### express-zod-api

A great lib that provided some insights on dealing with various zod types.

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This library is part of a nx monorepo @anatine/zod-plugins.