How to test synchronization between rails application and mobile client? - ruby-on-rails

Question

We need to be sure that our web application and mobile client are communicating correctly.
There is two-side communications from the server (Rails application with rspec testing) to the mobile client (Ruby application, has mspec testing framework) and from the mobile client to the server.
So to be sure that the synchronization mechanism is working as expected we need to test the following things:
Server prepares the data correctly.
Mobile client requests and gets
correct data.
Mobile client
prepares
the data to be sent to the server
correctly.
Server recieves and
parses the correct data from the
mobile client.
Servers sends
response to mobile client that
everything is ok.
Mobile client
should carry out appropriate actions
on the device.
How to test this in isolation?

Answer 1

As for all tests, don't plan for the unexpected. Start with what you know. The unexpected will rear it's ugly head soon enough to tell you what else you should test.
What you have is actually simple to test if you break it apart. Here is my approach:
public final static String SERVER_DATA = "Prepared data from the server";
#Test
public void testServerPreparesDataCorrectly() throws Exception {
... usual setup ...
String actual = server.handleRequest( CLIENT_REQUEST );
assertEquals( SERVER_DATA, actual );
}
public final static String CLIENT_REQUEST = "...";
#Test
public void testClientRequest() throws Exception {
... usual setup ...
String actual = client.getRequestData(...);
assertEquals( CLIENT_REQUEST, actual );
}
#Test
public void testClientResponseProcessing() throws Exception {
... usual setup ...
client.parseServerResponse( SERVER_DATA );
... verify client state ...
}
and so on. The basic idea is to put the input and output of each process step into a constant, then run the code which implements the process step for each expected input and validate the output. Where most outputs are also inputs for other tests.
If something changes, you update the inputs/outputs accordingly. Run the tests. And the failures will tell you which process steps you have to update.