withstopwatch 0.0.10

Stopwatch as a context manager.

Basic usage:
>>> with Stopwatch():
...     pass
0 ms

Using fields:
>>> with Stopwatch() as s:
...     pass
0 ms
>>> assert isinstance(s.ms, int) and s.ms == 0
>>> assert isinstance(s.s, int) and s.s == 0
>>> assert isinstance(s.seconds, float) and s.seconds > 0
>>> assert isinstance(s.timedelta, datetime.timedelta)
>>> assert isinstance(s.start, datetime.datetime)
>>> assert isinstance(s.stop, datetime.datetime)

Silence options:
>>> with Stopwatch(template=None) as s:
...     pass
>>> assert s.label is None
>>> with Stopwatch(file=None) as s:
...     pass
>>> assert s.label == '0 ms'

With different templates:
>>> with Stopwatch(template='passing') as s:
...     pass
0 ms: passing
>>> with Stopwatch('passing') as s:
...     pass
0 ms: passing
>>> with Stopwatch('{ms} ms') as s:
...     pass
0 ms
>>> with Stopwatch('{s} s') as s:
...     pass
0 s
>>> with Stopwatch('{:.03f} (i.e. {seconds:.03f})') as s:
...     pass
0.000 (i.e. 0.000)
>>> with Stopwatch('{timedelta}') as s:
...     pass   # doctest: +ELLIPSIS
0:00:00.000...
>>> with Stopwatch('from {start!r} to {stop!r}') as s:
...     pass   # doctest: +ELLIPSIS
from datetime.datetime(...) to datetime.datetime(...)
>>> assert s.stop - s.start == s.timedelta

With an exception:
>>> with Stopwatch(file=None) as s:
...     raise Exception()
Traceback (most recent call last):
Exception
>>> try:
...     with Stopwatch() as s:
...        raise Exception()
... except Exception as exc:
...     print(type(exc))
0 ms
<class 'Exception'>

Testing with `time.sleep` (note: the tests may fail during a slower run):
>>> import time
>>> with Stopwatch() as s:
...     time.sleep(0.1)
100 ms
>>> assert 0.1 < s.seconds < 0.2

Embedded stopwatchs:
>>> with Stopwatch() as s:
...     with Stopwatch('s2') as s2:
...         pass
0 ms: s2
0 ms

Measuring the overhead of Stopwatch using Stopwatch itself
(note: the tests may fail during a slower run):
>>> with Stopwatch(file=None) as s1:
...     with Stopwatch('s2') as s2:
...         pass
0 ms: s2
>>> with Stopwatch(file=None) as s3:
...     pass
>>> overhead = s1.seconds - s3.seconds
>>> assert 0 <= overhead < 0.0001  # actually ~20 us on i5@2.60GHz, Linux