corda/docs/source/api-testing.rst

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API: Testing
============

.. contents::

Flow testing
------------

MockNetwork
^^^^^^^^^^^

Flow testing can be fully automated using a ``MockNetwork`` composed of ``StartedMockNode`` nodes. Each
``StartedMockNode`` behaves like a regular Corda node, but its services are either in-memory or mocked out.

A ``MockNetwork`` is created as follows:

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    .. literalinclude:: ../../docs/source/example-code/src/main/java/net/corda/docs/java/MockNetworkTestsTutorial.java
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The ``MockNetwork`` requires at a minimum a list of CorDapps to be installed on each ``StartedMockNode``. The CorDapps are looked up on the
classpath by package name, using ``TestCordapp.findCordapp``. ``TestCordapp.findCordapp`` scans the current classpath to find the CorDapp that contains the given package.
This includes all the associated CorDapp metadata present in its MANIFEST.

``MockNetworkParameters`` provides other properties for the network which can be tweaked. They default to sensible values if not specified.

Adding nodes to the network
^^^^^^^^^^^^^^^^^^^^^^^^^^^

Nodes are created on the ``MockNetwork`` using:

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Nodes added using ``createNode`` are provided a default set of node parameters. However, it is also possible to
provide different parameters to each node using ``MockNodeParameters``. Of particular interest are ``configOverrides`` which allow you to
override some of the default node configuration options. Please refer to the ``MockNodeConfigOverrides`` class for details what can currently
be overridden. Also, the ``additionalCordapps`` parameter allows you to add extra CorDapps to a specific node. This is useful when you wish
for all nodes to load a common CorDapp but for a subset of nodes to load CorDapps specific to their role in the network.

Running the network
^^^^^^^^^^^^^^^^^^^
When using a ``MockNetwork``, you must be careful to ensure that all the nodes have processed all the relevant messages 
before making assertions about the result of performing some action. For example, if you start a flow to update the ledger 
but don't wait until all the nodes involved have processed all the resulting messages, your nodes' vaults may not be in 
the state you expect.

When ``networkSendManuallyPumped`` is set to ``false``, you must manually initiate the processing of received messages. 
You manually process received messages as follows:

* ``StartedMockNode.pumpReceive()`` processes a single message from the node's queue
* ``MockNetwork.runNetwork()`` processes all the messages in every node's queue until there are no further messages to
  process
      
When ``networkSendManuallyPumped`` is set to ``true``, nodes will automatically process the messages they receive. You 
can block until all messages have been processed using ``MockNetwork.waitQuiescent()``.

.. warning:: If ``threadPerNode`` is set to ``true``, ``networkSendManuallyPumped`` must also be set to ``true``.

Running flows
^^^^^^^^^^^^^

A ``StartedMockNode`` starts a flow using the ``StartedNodeServices.startFlow`` method. This method returns a future
representing the output of running the flow.

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   .. sourcecode:: kotlin

        val signedTransactionFuture = nodeA.services.startFlow(IOUFlow(iouValue = 99, otherParty = nodeBParty))

   .. sourcecode:: java

        CordaFuture<SignedTransaction> future = startFlow(a.getServices(), new ExampleFlow.Initiator(1, nodeBParty));

The network must then be manually run before retrieving the future's value:

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   .. sourcecode:: kotlin

        val signedTransactionFuture = nodeA.services.startFlow(IOUFlow(iouValue = 99, otherParty = nodeBParty))
        // Assuming network.networkSendManuallyPumped == false.
        network.runNetwork()
        val signedTransaction = future.get();

   .. sourcecode:: java

        CordaFuture<SignedTransaction> future = startFlow(a.getServices(), new ExampleFlow.Initiator(1, nodeBParty));
        // Assuming network.networkSendManuallyPumped == false.
        network.runNetwork();
        SignedTransaction signedTransaction = future.get();

Accessing ``StartedMockNode`` internals
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Querying a node's vault
~~~~~~~~~~~~~~~~~~~~~~~

Recorded states can be retrieved from the vault of a ``StartedMockNode`` using:

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   .. sourcecode:: kotlin

        val myStates = nodeA.services.vaultService.queryBy<MyStateType>().states

   .. sourcecode:: java

        List<MyStateType> myStates = node.getServices().getVaultService().queryBy(MyStateType.class).getStates();

This allows you to check whether a given state has (or has not) been stored, and whether it has the correct attributes.


Examining a node's transaction storage
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Recorded transactions can be retrieved from the transaction storage of a ``StartedMockNode`` using:

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   .. sourcecode:: kotlin

        val transaction = nodeA.services.validatedTransactions.getTransaction(transaction.id)

   .. sourcecode:: java

        SignedTransaction transaction = nodeA.getServices().getValidatedTransactions().getTransaction(transaction.getId())

This allows you to check whether a given transaction has (or has not) been stored, and whether it has the correct
attributes.

This allows you to check whether a given state has (or has not) been stored, and whether it has the correct attributes.

Further examples
^^^^^^^^^^^^^^^^

* See the flow testing tutorial :doc:`here <flow-testing>`
* See the oracle tutorial :doc:`here <oracles>` for information on testing ``@CordaService`` classes
* Further examples are available in the Example CorDapp in
  `Java <https://github.com/corda/samples/blob/release-V|platform_version|/cordapp-example/workflows-java/src/test/java/com/example/flow/IOUFlowTests.java>`_ and
  `Kotlin <https://github.com/corda/samples/blob/release-V|platform_version|/cordapp-example/workflows-kotlin/src/test/kotlin/com/example/flow/IOUFlowTests.kt>`_

Contract testing
----------------

The Corda test framework includes the ability to create a test ledger by calling the ``ledger`` function
on an implementation of the ``ServiceHub`` interface.

Test identities
^^^^^^^^^^^^^^^

You can create dummy identities to use in test transactions using the ``TestIdentity`` class:

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``TestIdentity`` exposes the following fields and methods:

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   .. sourcecode:: kotlin

        val identityParty: Party = bigCorp.party
        val identityName: CordaX500Name = bigCorp.name
        val identityPubKey: PublicKey = bigCorp.publicKey
        val identityKeyPair: KeyPair = bigCorp.keyPair
        val identityPartyAndCertificate: PartyAndCertificate = bigCorp.identity

   .. sourcecode:: java

        Party identityParty = bigCorp.getParty();
        CordaX500Name identityName = bigCorp.getName();
        PublicKey identityPubKey = bigCorp.getPublicKey();
        KeyPair identityKeyPair = bigCorp.getKeyPair();
        PartyAndCertificate identityPartyAndCertificate = bigCorp.getIdentity();

You can also create a unique ``TestIdentity`` using the ``fresh`` method:

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   .. sourcecode:: kotlin

        val uniqueTestIdentity: TestIdentity = TestIdentity.fresh("orgName")

   .. sourcecode:: java

        TestIdentity uniqueTestIdentity = TestIdentity.Companion.fresh("orgName");

MockServices
^^^^^^^^^^^^

A mock implementation of ``ServiceHub`` is provided in ``MockServices``. This is a minimal ``ServiceHub`` that
suffices to test contract logic. It has the ability to insert states into the vault, query the vault, and
construct and check transactions.

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Alternatively, there is a helper constructor which just accepts a list of ``TestIdentity``. The first identity provided is
the identity of the node whose ``ServiceHub`` is being mocked, and any subsequent identities are identities that the node
knows about. Only the calling package is scanned for cordapps and a test ``IdentityService`` is created
for you, using all the given identities.

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Writing tests using a test ledger
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``ServiceHub.ledger`` extension function allows you to create a test ledger. Within the ledger wrapper you can create
transactions using the ``transaction`` function. Within a transaction you can define the ``input`` and
``output`` states for the transaction, alongside any commands that are being executed, the ``timeWindow`` in which the
transaction has been executed, and any ``attachments``, as shown in this example test:

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Once all the transaction components have been specified, you can run ``verifies()`` to check that the given transaction is valid.

Checking for failure states
~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to test for failures, you can use the ``failsWith`` method, or in Kotlin the ``fails with`` helper method, which
assert that the transaction fails with a specific error. If you just want to assert that the transaction has failed without
verifying the message, there is also a ``fails`` method.

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.. note::

    The transaction DSL forces the last line of the test to be either a ``verifies`` or ``fails with`` statement.

Testing multiple scenarios at once
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Within a single transaction block, you can assert several times that the transaction constructed so far either passes or
fails verification. For example, you could test that a contract fails to verify because it has no output states, and then
add the relevant output state and check that the contract verifies successfully, as in the following example:

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You can also use the ``tweak`` function to create a locally scoped transaction that you can make changes to
and then return to the original, unmodified transaction. As in the following example:

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Chaining transactions
~~~~~~~~~~~~~~~~~~~~~

The following example shows that within a ``ledger``, you can create more than one ``transaction`` in order to test chains
of transactions. In addition to ``transaction``, ``unverifiedTransaction`` can be used, as in the example below, to create
transactions on the ledger without verifying them, for pre-populating the ledger with existing data. When chaining transactions,
it is important to note that even though a ``transaction`` ``verifies`` successfully, the overall ledger may not be valid. This can
be verified separately by placing a ``verifies`` or ``fails`` statement  within the ``ledger`` block.

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Further examples
^^^^^^^^^^^^^^^^

* See the flow testing tutorial :doc:`here <tutorial-test-dsl>`
* Further examples are available in the Example CorDapp in
  `Java <https://github.com/corda/samples/blob/release-V|platform_version|/cordapp-example/workflows-java/src/test/java/com/example/flow/IOUFlowTests.java>`_ and
  `Kotlin <https://github.com/corda/samples/blob/release-V|platform_version|/cordapp-example/workflows-kotlin/src/test/kotlin/com/example/flow/IOUFlowTests.kt>`_