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Configuration

Fakelab uses a configuration file to define how your mock server should behave.

Configuration File​

Create a fakelab.config.ts file in your project root:

import { defineConfig } from "fakelab";

export default defineConfig({
  sourcePath: ["./types", "./fixtures/**/*.ts"], // supports glob pattern
  faker: { locale: "en" }, // optional
  server: { pathPrefix: "api/v1", port: 8080 }, // optional
  database: { enabled: true }, // optional
  network: { delay: [300, 1200] }, // optional
});

Configuration Options​

sourcePath​

An array of paths to TypeScript files or directories containing your type definitions.

  • Type: string | string[]
  • Required: Yes
  • Example: ["./types", "./fixtures/**/*.ts"]

Supports glob patterns for flexible file matching.

faker​

Configuration for Faker.js data generation.

  • Type: { locale?: string }
  • Required: No
  • Default: { locale: "en" }

Available locales: en, fr, de, es, pt, it, nl, pl, ru, ja, ko, zh_CN, zh_TW, and more.

server​

Server configuration options.

  • Type: { pathPrefix?: string, port?: number, includeSnapshots?: boolean }

  • Required: No

  • Default: { pathPrefix: "api", port: 50000 }

  • pathPrefix: Prefix for all generated API routes

  • port: Port number to run the server on

  • includeSnapshots : Includes the snapshot typescript sources if exists.

database​

Database persistence configuration.

  • Type: { enabled?: boolean }
  • Required: No
  • Default: { enabled: false }

When enabled, Fakelab persists generated mock data to a local JSON database.

network​

Network simulation configuration.

  • Type: { delay?: number | [number, number], errorRate?: number, timeoutRate?: number, offline?: boolean, preset?: string, presets?: Record<string, NetworkBehaviourOptions> }
  • Required: No

Simulate real-world network conditions:

  • delay: Response delay in milliseconds (single value or range)
  • errorRate: Probability of errors (0-1)
  • timeoutRate: Probability of timeouts (0-1)
  • offline: Force offline mode
  • preset: Use a predefined network preset
  • presets: Define custom network presets

Example Configurations​

Basic Configuration​

import { defineConfig } from "fakelab";

export default defineConfig({
  sourcePath: ["./fixtures"],
});

Advanced Configuration​

import { defineConfig } from "fakelab";

export default defineConfig({
  sourcePath: ["./types", "./fixtures/**/*.ts"],
  faker: { locale: "fr" },
  server: {
    pathPrefix: "/api/v1",
    port: 4000,
  },
  database: { enabled: true },
  network: {
    delay: [200, 800],
    errorRate: 0.05,
    presets: {
      slow: { delay: [1000, 3000] },
      unreliable: { errorRate: 0.3 },
    },
    preset: "slow",
  },
});

Next Steps​