Create script for generating dummy telemetry data for tests

[MJJoyce]

Per @MJJoyce

Having a script for generating dummy telemetry data with marching values, data within specific ranges, etc. would be useful when trying to test new functionality.

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Per @bbornstein

Yes, that would be great. Given a PacketDefinition, it's straightforward:

defn = tlm.getDefaultDict()[packetName]
data = bytearray(xrange(defn.nbytes))
pkt  = tlm.Packet(defn, data)

This should really be a method on PacketDefinition, e.g.:

def simulate(fill=None):
    size   = self.nbytes
    values = xrange(size) if fill is None else ((fill,) * size)
    return Packet(self, bytearray(data))

(I chose simulate() as it seems somehow analogous to validate().) Any script could then easily simulate packets:

defn = tlm.getDefaultDict()[packetName]
pkt  = defn.simulate()
...

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Per @MJJoyce

+1, I like the simulate() choice as well