Blank asset numbers, contested device claims, and honest toner forecasting

tests/test_plugins/test_supply_history.py

@@ -267,3 +267,75 @@ def test_forecast_endpoint_says_so_when_zabbix_is_absent(client, db):
     assert 'not configured' in body['reason']
     assert body['cartridges'] == []
     assert body['orderlist'] == []
+
+
+# --------------------------------------------------------------------------
+# Noise that used to read as cartridge changes, and bursts that used to bias
+# the rate for the life of the cartridge. Both were reported from the floor:
+# "5 changes in 90 days, that's hard to believe", and a cartridge that dropped
+# 20 percent in two days then barely moved.
+# --------------------------------------------------------------------------
+
+def test_a_poll_returning_zero_is_not_a_cartridge_change():
+    """0 then a real level is an SNMP error or a calibrating printer.
+
+    The rise is +60, which cleared the old threshold on its own. It does not
+    land near full, so it is not a swap.
+    """
+    points = normalise(series([70, 60, 0, 60, 55, 50]))
+    assert find_replacements(points) == []
+
+
+def test_a_gauge_ticking_back_up_mid_range_is_not_a_change():
+    """A coarse gauge after a reseat or a power cycle. Lands at 55, not full."""
+    points = normalise(series([70, 60, 45, 55, 50, 45]))
+    assert find_replacements(points) == []
+
+
+def test_a_real_swap_is_still_counted():
+    """Near-empty to near-full. The shape a cartridge change actually makes."""
+    points = normalise(series([30, 15, 5, 100, 95, 90]))
+    assert len(find_replacements(points)) == 1
+
+
+def test_the_run_starts_at_the_real_swap_not_at_the_noise():
+    """current_run and find_replacements must agree on what a change is.
+
+    They read the same predicate now; when they did not, a phantom rise reset
+    the run and threw away the history the estimate needed.
+    """
+    points = normalise(series([90, 0, 85, 80, 75, 70]))
+    assert find_replacements(points) == []
+    assert len(current_run(points)) == len(points)
+
+
+def test_an_early_burst_does_not_dominate_the_rate_forever():
+    """20 percent in two days, then a month of almost nothing.
+
+    The endpoint slope reads the burst forever: (100-75)/30 = 0.83 %/day, so
+    the report keeps promising the cartridge runs out long after printing
+    stopped. The median sees one fast interval among many quiet ones.
+    """
+    levels = [100, 90, 80] + [80 - i * 0.2 for i in range(1, 28)]
+    rate = burn_rate(normalise(series(levels)))
+    assert rate is not None
+    assert rate < 1.0, rate
+    detail = analyse(series(levels))
+    assert detail['rateunstable'] is True
+
+
+def test_a_steady_cartridge_is_not_flagged_unstable():
+    detail = analyse(series([100, 95, 90, 85, 80, 75, 70]))
+    assert detail['burnrateperday'] == 5.0
+    assert detail['rateunstable'] is False
+
+
+def test_a_real_near_empty_reading_before_a_swap_is_kept():
+    """30, 5, 100 is a cartridge run to the end and changed - not a spike.
+
+    The dip filter must not eat it: the 5 does not RECOVER to 30, it jumps to
+    full, which is the shape of a swap rather than of a bad poll.
+    """
+    points = normalise(series([40, 30, 5, 100, 95, 90]))
+    assert 5.0 in [level for _, level in points]
+    assert len(find_replacements(points)) == 1