Use approx_time to compare timedeltas in tests

pytest 9.1.0 added proper support for `datetime`/`timedelta` in
`pytest.approx()`, and as part of it, it now refuses to guess a
tolerance for these types, raising instead:

    TypeError: pytest.approx() requires an explicit tolerance for
    datetime/timedelta comparisons: e.g. approx(expected,
    abs=timedelta(seconds=1)) or approx(expected, rel=0.01)

This broke 12 tests in `test_clocksinfo.py` and `test_config.py`, which
were using the bare `pytest.approx()` on `timedelta`s instead of the
`approx_time()` helper used everywhere else in this test package.

These assertions never really used a tolerance anyway: all the compared
values are exact, so they only ever succeeded through the exact-equality
short-circuit in `approx()`, before any tolerance was computed.

Switching them to `approx_time()` provides the required tolerance (1ms
by default) and makes the whole test package consistent.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

Author: llucax

tests/timeseries/_resampling/wall_clock_timer/test_clocksinfo.py

@@ -12,6 +12,8 @@
 
 from frequenz.sdk.timeseries._resampling._wall_clock_timer import ClocksInfo
 
+from .util import approx_time
+
 _DEFAULT_MONOTONIC_REQUESTED_SLEEP = timedelta(seconds=1.0)
 _DEFAULT_MONOTONIC_TIME = 1234.5
 _DEFAULT_WALL_CLOCK_TIME = datetime(2023, 1, 1, tzinfo=timezone.utc)
@@ -141,7 +143,7 @@ def test_monotonic_drift(
         monotonic_elapsed=monotonic_elapsed,
         wall_clock_elapsed=_DEFAULT_WALL_CLOCK_ELAPSED,
     )
-    assert info.monotonic_drift == pytest.approx(expected_drift)
+    assert info.monotonic_drift == approx_time(expected_drift)
 
 
 @pytest.mark.parametrize(
@@ -166,7 +168,7 @@ def test_wall_clock_jump(
         monotonic_elapsed=monotonic_elapsed,
         wall_clock_elapsed=wall_clock_elapsed,
     )
-    assert info.wall_clock_jump == pytest.approx(expected_jump)
+    assert info.wall_clock_jump == approx_time(expected_jump)
 
 
 @dataclass(kw_only=True, frozen=True)
@@ -219,7 +221,7 @@ def test_wall_clock_factor(case: _TestCaseWallClockFactor) -> None:
         wall_clock_elapsed=case.wall_clock_elapsed,
     )
     assert info.wall_clock_factor == pytest.approx(case.expected_factor)
-    assert info.wall_clock_to_monotonic(case.wall_clock_elapsed) == pytest.approx(
+    assert info.wall_clock_to_monotonic(case.wall_clock_elapsed) == approx_time(
         case.monotonic_elapsed
     )
 

tests/timeseries/_resampling/wall_clock_timer/test_config.py

@@ -12,15 +12,17 @@
 
 from frequenz.sdk.timeseries._resampling._wall_clock_timer import WallClockTimerConfig
 
+from .util import approx_time
+
 
 def test_from_interval_defaults() -> None:
     """Test WallClockTimerConfig.from_interval() with only interval (all defaults)."""
     interval = timedelta(seconds=10)
     config = WallClockTimerConfig.from_interval(interval)
     assert config.align_to == UNIX_EPOCH
-    assert config.async_drift_tolerance == pytest.approx(timedelta(seconds=1.0))
+    assert config.async_drift_tolerance == approx_time(timedelta(seconds=1.0))
     assert config.wall_clock_drift_tolerance_factor == pytest.approx(0.1)
-    assert config.wall_clock_jump_threshold == pytest.approx(timedelta(seconds=10.0))
+    assert config.wall_clock_jump_threshold == approx_time(timedelta(seconds=10.0))
 
 
 def test_from_interval_all_args() -> None:
@@ -38,9 +40,9 @@ def test_from_interval_all_args() -> None:
         wall_clock_jump_threshold_factor=jump_factor,
     )
     assert config.align_to == align_to
-    assert config.async_drift_tolerance == pytest.approx(timedelta(seconds=1.0))
+    assert config.async_drift_tolerance == approx_time(timedelta(seconds=1.0))
     assert config.wall_clock_drift_tolerance_factor == pytest.approx(0.3)
-    assert config.wall_clock_jump_threshold == pytest.approx(timedelta(seconds=2.0))
+    assert config.wall_clock_jump_threshold == approx_time(timedelta(seconds=2.0))
 
 
 @pytest.mark.parametrize(