The LambdaTestAsync was an extension to LambdaTest with support for asynchronous testing. It was developed between Dec 2016 and Feb 2017. 47 Degrees has discontinued the development and maintenance of this extension. The source code is left here for those interested in studying it.
LambdaTestAsync is an extension to LambdaTest. LambdaTest is a functional testing library for Scala. LambdaTestAsync extends LambdaTest with support for asynchronous testing.
One of the goals of LambdaTest was to provide a small clean system that can be easily
extended to suport new features and to customize it for specific projects.
The core API is LambdaAct which is a pure functional transform from one LambdaState to the
next LambdaState. A composition of simple and compound LambdaAct's is central to
each user written test.
LambdaTestAsync is a good example of this extensibility where without any changes
to the base system, it adds async support by defining the new expectEvents[T] LambdaAct.
You should review the features of the base LambdaTest system before reading the documentation below.
Include LambdaTestAsync jars
"com.fortysevendeg" % "lambda-test-async_2.12" % "1.3.0" % "test"
In your tests include
import com.fortysevendeg.lambdatest._
import com.fortysevendeg.lambdatestasync._
LambdaTestAsync is based on streams of asynchronous events. Assertions test that these streams have specified properties.
There is a general purpose set of features that can be used on any kind of event streams. Two specializations are provided:
- Akka actor messages.
- Logged messages.
See the TestActor demo. Here we are testing a stateful Actor A that responds to messages sent to it and also sends messages to another Actor B.
To set up the Akka actor system, the actorSystemWrap wrapper is used.
A Probe is used to send messages to A and to record its responses in event stream pEvents. An Intercept is used between A and B to record messages sent from A to B in event stream bEvents.
The test is done with the expectEvents compound assertion action. Note the optional show parameter that
when set prints out the sequence of events. The test has two parts. The first part is the body that will cause
the events to be generated. When the SendMsg(a,Ping) is sent to the probe, the probe sends the message Ping to A.
The second part is the test. Here each list of messages must exectly match a specified list.
There are two kinds of build-in tests.
HasExact. the list of events must exactly match a specified list.Has. the list of events must contain all the elements of a specified list in order. The list of events may also contain other events.
It is also possible to write your own tests. Each custom test should extend the EventTest[T] trait where T is the type of the events.
You will need to implement the test method of EventTest. This method is called once for each event and once after all events (typically as the result of a timeout). It has two parameters.
events. The list of all events so far in reverse order (the head will be the most recent event).done. Set to true only on the last call.
There are three possible results.
Success. The test succeeded. No further processing is needed.Fail. The test failed. No further processing is needed. Fail includes a text message that describes why the test failed.Continue. Keep testing. (If done is true, the test will fail, since there is nothing to continue to).
See the TestLog demo. This demo uses the pure Scala Persist Logger where messages are logged as Json.
The example uses two wrapper. The actorSystemWrap sets up the Akka actor context. The logWrap wrapper sets us the Persist logger and defines the log message event stream logEvents.
The LogTest test matches Json messages be euqality tests on selected field.
LambdaTestAsync is not limited to just streams of Actor messages or Json logs. Other kinds of event streams can be supported by extending the Events[T] trait. The two built-in streams use Akka actors within their implementation and their code can serve as samples for adding new stream types.
As discussed above it is also possible to write customized tests by extending the EventTest[T] trait. Custom event output can be provided by defining new values for the expectEvents show parameter with type Some[T=>String] which converts each event into a print string.