Hello! Is there any way to unit test the `isFromCa...

# apollo-kotlin

[Marcel]

Hello! Is there any way to unit test the isFromCache property on a KMP project in commonTest without building a wrapper? I have tried using MockServer and MockResponse, but I see nothing cache-related there.

Silly implementation example:

class DataSource(private val apolloClient: ApolloClient) {

    suspend fun getResponse(): CustomObj {
        val response = apolloClient
            .query(RandomQuery())
            .fetchPolicy(FetchPolicy.NetworkFirst)
            .execute()

        val isFromCache = response.isFromCache
        
        return CustomObj(
            isCache = isFromCache,
            data = // parsing data
        )
    }
}

I want to be able to mock the isFromCache in the Apollo responses of my unit tests.

I have also tried building my own mock Apollo response like this:

val isFromCache = true        
val executionContext = mock<ExecutionContext>() {
    every { get(CacheInfo) } returns CacheInfo.Builder()
        .cacheHit(isFromCache)
        .build()
}

return ApolloResponse.Builder(
    operation = mock<Operation<GetTodayTabQuery.Data>>(),
    requestUuid = uuid4()
)
.data(mockData)
.addExecutionContext(executionContext)
.build()

However, I'm not sure you can use MockServer to return a real ApolloResponse object (just a MockResponse).

[mbonnin]

You can mock the NetworkTransport I think? This is what returns an ApolloResponse

[mbonnin]

MockServer works at the HTTP layer, NetworkTransport at the GraphQL layer

[Marcel]

Thanks! That worked. For anyone's future reference, this is how I mocked the client and the network transport to change the isFromCache property:

private fun createMockApolloClient(
        timestamp: Double,
        isFromCache: Boolean,
) = ApolloClient.Builder()
        .networkTransport(CustomTestNetworkTransport(timestamp, isFromCache))
        .build()

private class CustomTestNetworkTransport(
    private val timestamp: Double,
    private val isFromCache: Boolean,
) : NetworkTransport {
    override fun <D : Operation.Data> execute(request: ApolloRequest<D>): Flow<ApolloResponse<D>> = flowOf(
        createMockApolloResponseFromCache() as ApolloResponse<D>
    )

    override fun dispose() {}

    private fun createMockApolloResponseFromCache(): ApolloResponse<RandomQuery.Data> {
        val mockQuery = getMockResponse(timestamp)

        val executionContext = mock<ExecutionContext> {
            every { get(CacheInfo) } returns CacheInfo.Builder()
                .cacheHit(isFromCache)
                .build()
        }

        return ApolloResponse.Builder(
            operation = mock<Operation<RandomQuery.Data>>(),
            requestUuid = uuid4()
        )
            .data(mockQuery)
            .addExecutionContext(executionContext)
            .build()
    }
}