GraphQL fixture generation library that generates mock data based on the GraphQL schema and TypedDocumentNodes. A graphql fixture consists of two different data types:

• Variables: The input variables for the query or mutation.
• Data: The output data from the query or mutation.

The library generates mock data from typed document nodes, which are fully typed GraphQL document nodes. Therefore, it's advised to use graphql-codegen to generate the typed document nodes.

• Installation
• Usage
• Accurate data generation
• Options
• Resolving paths
• Overriding values

npm i -D @mocking-bird/graphql

Parsing the schema from the GraphQL schema string:

import { GraphQLFixture } from '@mocking-bird/graphql';

const typeDefs = `
  type User {
    name: String
    email: String
    age: Int
    workEmail: String
    address: Address
    createdAt: Date
    updatedAt: Date
  }

  type Address {
    street: String
    city: String
    country: String
  }
`;

GraphQLFixture.registerSchema(typeDefs);

Parsing the schema from a file:

import { GraphQLFixture } from '@mocking-bird/graphql';

GraphQLFixture.registerSchemaFromFile('path/to/schema.graphql');

import { GraphQLFixture } from '@mocking-bird/graphql';

/**
 * TypedDocumentNode generated by graphql-codegen:
 *
 * export const GetQueryDocument: TypedDocumentNode<GetQuery, GetQueryVariables> = {
 *  kind: 'Document',
 *  definitions: [
 *    kind: 'OperationDefinition',
 *    operation: 'query',
 *    name: { kind: 'Name', value: 'GetQuery' },
 *    ...
 *  ]
 * }
 */

const fixture = new GraphQLFixture(GetQueryDocument);
fixture.generate();

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Generated data are not only random-random but also contextually accurate based on field names and types. It leverages the fuzzy search, or formally, approximate string search algorithm to search for the suitable faker to generate realistic data that relate to the field.

For example:

• workEmail -> Jerome.Mraz58@yahoo.com
• employeePhoneNumber -> 550-459-6013
• uploadedFileName -> file-1234.pdf

Of course, there are still some limitations when it comes to complex field names with multiple parts, in which case the default fakers are applied. The default fakers are fallbacks in case the fuzzy search score is not high enough. The default fakers may return, depending on the field type, a random string, number, or date, and so on.

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FieldPath is a string that represents the path of a field in the schema. It can be a nested path, such as address.street. It can also be a wildcard path, such as address.*, which means all fields under address.

fixture.generate(
  {},
  {
    exclude: ['createdAt', 'updatedAt'],
    isAccurate: false,
    requiredOnly: true,
    rules: [
      {
        path: 'address.city',
        enum: ['Berlin', 'Frankfurt'],
      },
      {
        path: 'age',
        min: 18,
        max: 60,
      },
      {
        path: 'workEmail',
        pattern: /@gmail.com$/,
      },
    ],
  },
);

By default, the library supports Date, DateTime and JSON scalar types. You can add custom scalar definitions by:

GraphQLFixture.setGlobalOptions({
  scalarDefinitions: {
    BeforeChristDate: {
      type: FieldType.DATE,
      defaultValue: '2021-01-01',
    },
  },
});

Defining field relations are useful, if you want to assign the same value to related fields. For example:

const fixture = new GraphQLFixture(GetQueryDocument, {
  fieldRelations: {
    'variables.user.id': 'data.user.id',
  },
});

Note: if you are matching fields, you should use the variables and data prefixes to the field path.

In this example, generated mock variable user.id will be assigned to the generated mock data user.id. This makes sense because the id field in the variables and data should be the same.

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When working with nested data structures, you may want to resolve the paths to the fields. This is especially useful when you want to exclude or apply rules to fields that are nested.

fixture.generate({}, { exclude: ['address.city'] });

You can also use wildcard paths to exclude or apply rules to all fields under a certain path:

fixture.generate({}, { exclude: ['address.*'] });

fixture.generate({
  'person.*.jobTitle': 'Software Engineer',
});

fixture.generate({
  'person.**.is*': true,
}); // will override every field that starts with `is` to true, e.g., isDefault, isCool etc...

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You can override the generated values by providing a map of values to override:

fixture.generate({
  name: 'John Doe',
  email: 'test@example.com',
  age: 25,
});

// or using wildcards

fixture.generate({
  'address.**.buildingNo': '1234',
});