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Integration testing
Integration testing involves bringing up nodes locally and testing invariants about them by starting flows and inspecting their state.
In this tutorial we will bring up three nodes Alice, Bob and a Notary. Alice will issue Cash to Bob, then Bob will send this Cash back to Alice. We will see how to test some simple deterministic and nondeterministic invariants in the meantime.
(Note that this example where Alice is self-issuing Cash is purely for demonstration purposes, in reality Cash would be issued by a bank and subsequently passed around.)
In order to spawn nodes we will use the Driver DSL. This DSL allows one to start up node processes from code. It manages a network map service and safe shutting down of nodes in the background.
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
The above code creates a User permissioned to start the
CashFlow protocol. It then starts up Alice and Bob with
this user, allowing us to later connect to the nodes.
Then the notary is started up. Note that we need to add
ValidatingNotaryService as an advertised service in order
for this node to serve notary functionality. This is also where flows
added in plugins should be specified. Note also that we won't connect to
the notary directly, so there's no need to pass in the test
User.
The startNode function returns a future that completes
once the node is fully started. This allows starting of the nodes to be
parallel. We wait on these futures as we need the information returned;
their respective NodeHandles s.
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
Next we connect to Alice and Bob respectively from the test process using the test user we created. Then we establish RPC links that allow us to start flows and query state.
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
We will be interested in changes to Alice's and Bob's vault, so we query a stream of vault updates from each.
Now that we're all set up we can finally get some Cash action going!
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
The first loop creates 10 threads, each starting a
CashFlow flow on the Alice node. We specify that we want to
issue i dollars to Bob, using the Notary as the notary
responsible for notarising the created states. Note that no notarisation
will occur yet as we're not spending any states, only entering new ones
to the ledger.
We started the flows from different threads for the sake of the
tutorial, to demonstrate how to test non-determinism, which is what the
expectEvents block does.
The Expect DSL allows ordering constraints to be checked on a stream
of events. The above code specifies that we are expecting 10 updates to
be emitted on the bobVaultUpdates stream in unspecified
order (this is what the parallel construct does). We
specify a (otherwise optional) match predicate to identify
specific updates we are interested in, which we then print.
If we run the code written so far we should see 4 nodes starting up (Alice,Bob,Notary + implicit Network Map service), then 10 logs of Bob receiving 1,2,...10 dollars from Alice in some unspecified order.
Next we want Bob to send this Cash back to Alice.
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
This time we'll do it sequentially. We make Bob pay 1,2,..10 dollars
to Alice in order. We make sure that a the CashFlow has
finished by waiting on startFlow 's
returnValue.
Then we use the Expect DSL again, this time using
sequence to test for the updates arriving in the order we
expect them to.
Note that parallel and sequence may be
nested into each other arbitrarily to test more complex scenarios.
That's it! We saw how to start up several corda nodes locally, how to
connect to them, and how to test some simple invariants about
CashFlow.
To run the complete test you can open
example-code/src/integration-test/kotlin/net/corda/docs/IntegrationTestingTutorial.kt
from IntelliJ and run the test, or alternatively use gradle:
# Run example-code integration tests
./gradlew docs/source/example-code:integrationTest -i