NetworkMapCache is empty in MockNetwork tests - corda

Question

I'm writing some lightweight flow tests with mocked everything and I ran into error that on all nodes NetworkMapService contains only the node itself. Identity service from the other hand contains all 3 nodes participating in a test.
net = MockNetwork()
issuer = net.createNode(legalName = CHARLIE.name)
alice = net.createNode(legalName = ALICE.name)
bob = net.createNode(legalName = BOB.name)
issuer.registerInitiatedFlow(IssueClaimFlow.Issuer::class.java)
alice.registerInitiatedFlow(VerifyClaimFlow.Prover::class.java)
MockServices.makeTestDatabaseAndMockServices(createIdentityService = { InMemoryIdentityService(listOf(ALICE_IDENTITY, BOB_IDENTITY, CHARLIE_IDENTITY), emptySet(), DEV_TRUST_ROOT) } )
net.registerIdentities()
net.runNetwork()
In this case flow goes well until first sendAndRecieve() call. There I get:
12:28:12.832 [Mock network] WARN net.corda.flow.[8f685c46-9ab6-4d64-b3f2-6b7476813c3b] - Terminated by unexpected exception
java.lang.IllegalArgumentException: Don't know about party C=ES,L=Madrid,O=Alice Corp
Funny thing that test is still finishes green (no useful work done thou). But its probably topic for another question.
I can overcome it with setting up cache manually like this:
alice.services.networkMapCache.addNode(issuer.info)
bob.services.networkMapCache.addNode(alice.info)
But is this correct way to go? I don't see something like this in samples or wherever.

Answer 1

If you look at the definition of MockNetwork.createNode, the networkMapAddress defaults to null.
Instead, you should use MockNetwork.createSomeNodes, which creates a network map node for you, then sets that node as the network map for every subsequent node it creates.
Here's an example from the CorDapp Example:
network = MockNetwork()
val nodes = network.createSomeNodes(2)
a = nodes.partyNodes[0]
b = nodes.partyNodes[1]
You can see the full example here: https://github.com/corda/cordapp-example/blob/release-V2/kotlin-source/src/test/kotlin/com/example/flow/IOUFlowTests.kt.