[U-Boot] Sandbox DT for testing (unit tests)

[Stephen Warren]

Simon,

I noticed that under sandbox, "ut dm" needs sandbox to have been started 
with arch/sandbox/dts/test.dtb. A few questions related to that:

a) Is it safe and does it make sense to always use that DT when running 
Sandbox for tests (e.g. under test/py)?

b) Does it make sense for that DT to be the default (perhaps bundled 
into the executable like other DT-using platforms, or perhaps the 
default value for the -d option if the user supplies none)?

c) Is it possible for "ut dm" to detect if the correct DT has been 
loaded (e.g. by reading some property only in that file as a marker) and 
only execute tests that don't rely on test.dtb if test.dtb isn't in use?

I think running "ut env" and "ut time" under test/py should be very 
easy, although the test log will only report overall status, not the 
status of each individual test within the ut invocation. That 
information will still be in the log file though. I'll go add tests for 
those two at least.