Added --timestamp option to monitor command.

[zvonler]

Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• The PR follows
  our contributing guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce?

New feature in the monitor that can add a timestamp to the beginning of each received line.

What is the current behavior?

No such option.

What is the new behavior?

When --timestamp is provided, the monitor wraps the output tty with a timestamping Writer. The format of the timestamps is YYYY-mm-dd HH:MM:SS.

Does this PR introduce a breaking change, and is titled accordingly?

Negative.

Other information

This is my first time writing Go (except for the sample program I used to work out the approach), so please review carefully.

There don't appear to be any docs specifically about the monitor command, nor tests of the CLI entry point.

The change was tested by hand using this sketch:

void setup()
{
    Serial.begin(115200);
}

static const uint32_t period = 100; // millis

void loop()
{
    static uint32_t last_print_tm = 0;
    static uint8_t next_ch = 0;
    static const char* message = "tick\n";
    if (millis() - last_print_tm > period) {
        Serial.print(message[next_ch++]);
        if (message[next_ch] == '\0')
            next_ch = 0;
        last_print_tm += period;
    }
    delay(10);
}

Testing confirmed that individual non-newline characters received are still output immediately, and only newline characters cause the timestamp output:

Zacharys-iMac:arduino-cli zvonler$ ./arduino-cli -b adafruit:avr:metro monitor -p /dev/cu.usbserial-015F62D6 -c baudrate=115200 --quiet
tick
tick
tick
tick
ti^C
Zacharys-iMac:arduino-cli zvonler$ ./arduino-cli -b adafruit:avr:metro monitor -p /dev/cu.usbserial-015F62D6 -c baudrate=115200 --quiet --timestamp
[2023-09-22 12:12:18] tick
[2023-09-22 12:12:19] tick
[2023-09-22 12:12:19] tick
[2023-09-22 12:12:20] tick
[2023-09-22 12:12:20] tic^C
Zacharys-iMac:arduino-cli zvonler$ 

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Patch coverage: 67.64% and project coverage change: +0.01% 🎉

Comparison is base (0e6133f) 63.03% compared to head (a664c2d) 63.04%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2336      +/-   ##
==========================================
+ Coverage   63.03%   63.04%   +0.01%     
==========================================
  Files         201      201              
  Lines       19264    19286      +22     
==========================================
+ Hits        12143    12159      +16     
- Misses       6067     6072       +5     
- Partials     1054     1055       +1     

Flag	Coverage Δ
unit	63.04% <67.64%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
internal/cli/monitor/monitor.go	22.90% <67.64%> (+7.21%)	⬆️

... and 26 files with indirect coverage changes

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[alessio-perugini]

👋 Thank you, for the contribution. The implementation looks good. 🤩
As you noticed, we do not have any integration tests for the monitor as we cannot provide a real board in the CI.
We can do a unit test in the same folder you're working on by creating a new monitor_test.go file. You can look at this for some inspiration. In this case, the package name doesn't need to have the suffix _test as we need to access a private function.

The idea is to test only the timeStampWriter. These are some hints:

• We call the newTimeStampWriter providing something that satisfies the io.Writer like (bytes.Buffer{})
• We "simulate" the data coming from the board by passing arbitrary input in the timeStampWriter.Write func
• Once done writing, we should be able to assert the content of the buffer if has the timestamp as a prefix.

Don't forget to run go fmt ./... from the root of the project. Or if you have task installed you can run task go:format. (That should solve the CI error)

If you need help don't hesitate to ping me I'd be more than happy to guide you. 💪

[zvonler]

Thanks for the pointers, I'll add a test like you described.

[zvonler]

Test added and formatting fixed.

[zvonler]

Oops, fixed that last formatting issue.

[alessio-perugini]

I've done some manual testing, and it works flawlessly. Thank you for your contribution and your patience. 🤓