NetworkMock Core

The devview-networkmock-core module is the shared engine for network mocking. It owns JSON config parsing, request matching, response file discovery, and DataStore state persistence. Both devview-networkmock (UI) and devview-networkmock-ktor (Ktor plugin) depend on it — it exists specifically to let those two modules share state without depending on each other.

mocks.json Format

Place at composeResources/files/networkmocks/mocks.json:

{
  "apiGroups": [
    {
      "id": "my-backend",
      "name": "My Backend",
      "endpoints": [
        { "id": "getUser", "name": "Get User", "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",
          "endpointOverrides": [
            { "id": "getUser", "path": "/v2/users/{userId}" }
          ],
          "additionalEndpoints": [
            { "id": "getLegacy", "name": "Legacy", "path": "/users", "method": "GET" }
          ]
        }
      ]
    }
  ]
}

Key concepts: - apiGroups: Logical backends, each with shared endpoints and multiple environments. - endpointOverrides: Per-environment path overrides for specific endpoint IDs. - additionalEndpoints: Endpoints that only exist in a specific environment. - {param} placeholders: Path segments like {userId} match any value during request matching.

Request Matching

MockConfigRepository.findMatchingMock(host, path, method) resolves a mock in three steps:

1. Hostname match — extracts the hostname from each EnvironmentConfig.url (strips scheme, port, path), compares case-insensitively against the incoming request host.
2. Path match — splits path by /, compares segment by segment; {param} segments match any value; non-param segments are case-sensitive.
3. Method match — case-sensitive exact match. Use uppercase ("GET", "POST").

There is no stored active-environment selection. The environment is determined purely from the request hostname at interception time, allowing simultaneous requests to multiple environments across groups.

Response File Discovery

Response files live under composeResources/files/networkmocks/responses/:

responses/{groupId}/{environmentId}/{endpointId}/{endpointId}-{status}[-{suffix}].json  ← highest priority
responses/{groupId}/{endpointId}/{endpointId}-{status}[-{suffix}].json                  ← shared fallback

The core module probes the following status codes by default: 200, 201, 202, 204, 400, 401, 403, 404, 409, 422, 429, 500, 502, 503, 504.

Default suffixes: "", "-simple", "-detailed", "-error", "-success".

If your API uses status codes outside the defaults, pass a custom list:

MockConfigRepository(
    configPath = "files/networkmocks/mocks.json",
    resourceLoader = NetworkMockResourceLoader { path -> Res.readBytes(path) },
    statusCodesToDiscover = listOf(200, 400, 503, 418)
)

DataStore Schema

State is persisted via MockStateRepository:

EndpointMockState is serialized as {"type":"network"} (pass-through) or {"type":"mock","responseFile":"getUser-200.json"}.

NetworkMockResourceLoader

Added in v0.1.3.

NetworkMockResourceLoader is a fun interface that abstracts how mock resource bytes are loaded from a path. It exists to support DI-friendly architectures where the mock JSON files live in a different Gradle module than the one constructing NetworkMock.

public fun interface NetworkMockResourceLoader {
    public suspend fun load(path: String): ByteArray
}

Basic Usage

NetworkMock(
    resourceLoader = NetworkMockResourceLoader { path -> Res.readBytes(path) }
)

DI Usage (Koin example)

In the module that owns the mock resource files:

single<NetworkMockResourceLoader> {
    NetworkMockResourceLoader { Res.readBytes(it) }
}

In the presentation module where NetworkMock is constructed:

val loader = koinInject<NetworkMockResourceLoader>()
val modules = rememberModules {
    module(NetworkMock(resourceLoader = loader))
}

Why This Exists

Before v0.1.3, NetworkMock accepted a raw suspend (String) -> ByteArray lambda. This worked but was impossible to register as a typed binding in DI frameworks (Koin, Hilt) across Gradle module boundaries. The named NetworkMockResourceLoader type solves this.

Related Modules

• NetworkMock: UI layer and module entry point.
• NetworkMock Ktor: Ktor client plugin.