Add Integration Test for Timestamp Behavior

[KonradBreitsprecherBkd]

The timestamp behavior had no integration test. The test covers:

Verify timestamp behavior from the synchronized participant perspective:

• Sync sender: outgoing event carries virtual send time.
• Async sender: outgoing events will have an invalid timestamp
• Sync receiver: incoming event from async or sync sender is timestamped with sync receive time.
• Async receiver: incoming event from async or sync sender keeps the timestamp (async sender: invalid timestamp, sync sender: send time)

[snps-behrens]

Just to clarify. I understood the timestamp behavior implementation in the sync -> sync situation to be that the send time (not the receive time) is used. If it were otherwise, wouldn't NetworkSimulator timestamps be overwritten?

The documentation seems to agree with me (though it is not explicilty stated): https://vectorgrp.github.io/sil-kit-docs/simulation/simulation.html#timestamps-in-messages.

[KonradBreitsprecherBkd]

Just to clarify. I understood the timestamp behavior implementation in the sync -> sync situation to be that the send time (not the receive time) is used. If it were otherwise, wouldn't NetworkSimulator timestamps be overwritten?

The documentation seems to agree with me (though it is not explicilty stated): https://vectorgrp.github.io/sil-kit-docs/simulation/simulation.html#timestamps-in-messages.

You're right, the logic is (taken from the code):

template <typename MsgT>
void SetTimestamp(MsgT& msg, std::chrono::nanoseconds value, std::enable_if_t<HasTimestamp<MsgT>::value, bool> = true)
{
    if (msg.timestamp == std::chrono::nanoseconds::duration::min())
    {
        msg.timestamp = value;
    }
}

This is: "On reception of a msg with an invalid timestamp (==from async), overwrite it with the local now() of the receiver"

So the comment above the test is misleading:
- Sync receiver: incoming event from async or sync sender is timestamped with sync receive time.
Also the SyncSubFromSync evaluation is off then.
Good catch, will rework!