Remote Testing

Software is not always run on the system where it is developped. Many factors may influence the software that is to be run on another target. In order to test software on systems that are not the test computer HWUT provides the ability of ‘remote testing’. In this type of test, the test application is run on a remote platform and communicates with HWUT over a communication protocol (currently only TCP is supported). Let the following terms be defined for clarification:

Host

The ‘host’ is the computer on which HWUT runs.

Target

The ‘target’ is the platform on which the tests shall be executed.

The target needs to contain the following two entities:

Agent

An ‘agent’ is a piece of software on the target that can receive and execute commands coming from the host.

Spy

A ‘spy’ has the task to send test application results to the host.

A remote test follows the scheme of normal tests. However, instead of executing the application in a system call it sends commands to the remote agent. The commands are the same as the command line arguments passed to test applications during non-remote tests, i.e. it would send the ASCII character sequence of “–hwut-info” to the agent in order to get information about the test itself. The test application answers by using the spy that is able to connect to the listener on the host and send it the output of the test. This data is the basis for comparison.

Before this can be done the application needs to be transferred to the remote platform. All mechanisms of building, transfer and test execution are controlled by HWUT. Figure fig-remote-testing shows the interactions to implement remote tests.

The first step is the build and transfer process. As in non-remote tests the test application needs to appear in the test returned by the hwut-info target in the Makefile. Next the build rule for the remote application must include the build of the test application, the transfer of the test application to the target, and if necessary the start of the listener on the the target side. For example

my_remoty: $(SOURCES)
     # Compile all related sources
     $(CROSS_COMPILER) $(SOURCES) $(HWUT_PATH)/support/remote/hwut_spy.c  -o my_remoty

     # Transfer the application to the target device
     ./my_target-transfer.sh my_remotey

     # Start our listener on the target
     ./my_target-start_listener.sh

Now, HWUT needs to know how to communicate with the target. For this, two it interviews the make rule hwut-remote and expects a string that specifies the spy and the agent on the remote target, e.g.

hwut-remote:
    @echo "SPY:   TCP;"
    @echo "AGENT: TCP, Adr=192.168.1.11, Path=/host/;"

specifies that both spy and agent on the target communicate over the TCP protocol. This will activate a special plug-in inside HWUT. After the protocol specifier a list of assigned parameters can be specified. The following parameters are valid for all protocols:

Path

This parameter defines the path to be prefixed for the remote execution. It influences the string that is sent to the target to trigger the test application execution–as will be explained below. This parameter makes only sense for the agent.

Terminator

This string determines what string terminates the report from the spy. As soon as the string appears, HWUT considers the test to be terminated. The default string is <<end>>. This parameter makes only sense for the spy.

Once the test application is built, transferred to the target, and the communication is set up the tests can be started. This happens by sending a string to the target. The string send to the target is the same as the string that would otherwise be applied to the command line, i.e:

/host/my_remote --hwut-info

will be sent in order to get information about the test, provided that Path in the above agent parameters was set to /host/. Now, the test application may respond via the spy with:

My Remote Application Test;
CHOICES: None, Some, All;

This is the information that HWUT requires to define the test sequence. It then sends:

/host/my_remote None

and receives the response from the remote spy, for example:

This is some test output from IP address 192.168.1.11.
No input, No output. Test ended.
<<end>>

This response needs to terminate with the a terminating string. As mentioned above the default string that HWUT expects is <<end>> but is can be modified with the parameter Terminator for the spy. Once, this string has been received HWUT compares the accumulated strings that it received from the target agains the nominal output in the GOOD directory.

TCP Parameters

Adr

For the agent this specifies the IP Address of the network node, where it resided. For the agent, the specification is mandatory. For the spy it specifies the IP Address where HWUT resides and receives messages. The spy does not need to specify this, since HWUT listens on all of its interfaces.

Port

For the agent, it is the port where it receives its commands. For the spy it is the port on the host to where it sends its data. By default HWUT uses port number 37773 for both.