Hyper-optimized Telemetry exercise struggling

[next star]

My code :

public static class TelemetryBuffer
{
    public static byte[] ToBuffer(long reading)
    {
        return BitConverter.GetBytes(reading);
    }

    public static long FromBuffer(byte[] buffer)
    {
        return BitConverter.ToInt64(buffer, 0);
    }
}```
Return not a single solution, the first one test return:
var bytes = TelemetryBuffer.ToBuffer(Int64.MaxValue);
Assert.Equal(new byte[] { 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f }, bytes);
Assert.Equal() Failure: Collections differ
           ↓ (pos 0)
Expected: [248, 255, 255, 255, 255, ···]
Actual:   [255, 255, 255, 255, 255, ···]
           ↑ (pos 0)

And I have no idea what is wrong, since the task should be simple because  it is introductory exercise

[quaint prawn]

What track is this?

Your code doesn't do any of the encoding. You appear to just be returning the input data directly.

There's an IntMax example in the instructions:

// Type: int, bytes: 4, signed: yes, prefix byte: 256 - 4
TelemetryBuffer.ToBuffer(Int32.MaxValue)
// => {0xfc, 0xff, 0xff, 0xff, 0x7f, 0x0, 0x0, 0x0, 0x0 };

Note when called with a Max value, the first byte is not 0xff.

[next star]

Yeah, you are right. It seems I didn't understand the task correctly, I will work on that.
Thank you

[quaint prawn]

You're welcome

Which track is this?

[final flax]

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[lethal field]

it's C#