NetworkMockPlugin

Ktor client plugin for intercepting HTTP requests and returning mock responses.

This plugin integrates with the DevView Network Mock module to allow developers to mock API calls during development and testing. It intercepts outgoing HTTP requests and can return predefined mock responses instead of making actual network calls.

Features

• Request Interception: Intercepts HTTP requests at the send phase

• Selective Mocking: Mock individual endpoints while others use real network

• Global Toggle: Master switch to enable/disable all mocking

• Path Parameters: Supports path parameters like /users/{userId}

• Multiple Hosts: Can mock different hosts (staging, production, etc.)

• State Persistence: Mock configuration persists across app restarts

How It Works

1. Plugin intercepts every HTTP request using Ktor's HttpSend mechanism

2. Checks if global mocking is enabled via DataStore state

3. Attempts to match the request (host, path, method) to a configured endpoint

4. If matched and mock is enabled for that endpoint, loads and returns the mock response

5. Otherwise, proceeds with the actual network call

Default Installation

When NetworkMock is registered via rememberModules, repositories are resolved automatically from com.worldline.devview.networkmock.core.NetworkMockInitializer:

val client = HttpClient(OkHttp) {
    install(NetworkMockPlugin)
}

Custom Installation

For testing or advanced scenarios, repositories can be injected explicitly:

val client = HttpClient(OkHttp) {
    install(NetworkMockPlugin) {
        mockRepository = myMockConfigRepository
        stateRepository = myMockStateRepository
    }
}

Mock File Setup

Create composeResources/files/networkmocks/mocks.json:

{
  "apiGroups": [{
    "id": "my-backend",
    "name": "My Backend",
    "endpoints": [{
      "id": "getUser",
      "name": "Get User Profile",
      "path": "/v1/users/{userId}",
      "method": "GET"
    }],
    "environments": [
      { "id": "staging",    "name": "Staging",    "url": "https://staging.api.example.com" },
      { "id": "production", "name": "Production", "url": "https://api.example.com" }
    ]
  }]
}

Add response files following the naming convention:

composeResources/files/networkmocks/responses/my-backend/getUser/
├── getUser-200.json        (shared — used by all environments)
└── getUser-404.json
composeResources/files/networkmocks/responses/my-backend/staging/getUser/
└── getUser-200.json        (staging-specific — overrides the shared variant)

Error Handling

The plugin fails gracefully — if configuration cannot be loaded, a response file is missing, or any exception occurs, it falls back to the actual network and logs the reason.

Thread Safety

The plugin is thread-safe. Multiple requests can be intercepted concurrently without issues. State reads are atomic through DataStore.

See also