prop/test/microwaveprop/weather/grid_snap_property_test.exs
Graham McIntire 581955bd69
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fix: prevent contacts_dedup_idx collisions in parallel async tests
Create shared ContactsFixtures module with globally-unique qso_timestamp
seconds to prevent unique-constraint violations when async test modules
run in parallel and insert contacts with identical dedup-key columns.
The qso_timestamp column is timestamp(0), so microsecond offsets were
truncated — use System.unique_integer monotonic seconds instead.

Also make count-asserting tests resilient to sandbox-leaked contacts
from prior tests by using >= assertions or status-based checks rather
than exact counts.

Includes automated DateTime.add → DateTime.shift migration from
mix format.
2026-08-04 17:05:16 -05:00

213 lines
7.2 KiB
Elixir

defmodule Microwaveprop.Weather.GridSnapPropertyTest do
@moduledoc """
Property tests for the coarse-grid / time-slot snapping helpers that
scattered across the Weather layer. Each of these functions maps a
continuous input onto a discrete set (the IEMRE 0.125° grid, top-of-hour
HRRR slots, 5-minute NEXRAD frames, 3-hourly NARR analyses). The
invariants every such snap must satisfy are idempotence, bounded
distance from the input, and grid-membership of the output.
"""
use ExUnit.Case, async: true
use ExUnitProperties
alias Microwaveprop.Weather
alias Microwaveprop.Weather.HrrrClient
alias Microwaveprop.Weather.NarrClient
alias Microwaveprop.Weather.NexradClient
describe "Weather.round_to_iemre_grid/2" do
property "is idempotent" do
check all(
lat <- float(min: -89.9, max: 89.9),
lon <- float(min: -179.9, max: 179.9)
) do
once = Weather.round_to_iemre_grid(lat, lon)
twice = then(once, fn {la, lo} -> Weather.round_to_iemre_grid(la, lo) end)
assert once == twice
end
end
property "output coordinates are multiples of 0.125°" do
check all(
lat <- float(min: -89.9, max: 89.9),
lon <- float(min: -179.9, max: 179.9)
) do
{rlat, rlon} = Weather.round_to_iemre_grid(lat, lon)
# 0.125 = 1/8, so 8 * coord must be an integer.
assert abs(rlat * 8 - round(rlat * 8)) < 1.0e-9
assert abs(rlon * 8 - round(rlon * 8)) < 1.0e-9
end
end
property "output is within half a grid cell (0.0625°) of the input" do
check all(
lat <- float(min: -89.9, max: 89.9),
lon <- float(min: -179.9, max: 179.9)
) do
{rlat, rlon} = Weather.round_to_iemre_grid(lat, lon)
# Float.round uses banker's rounding so the worst-case gap is
# exactly 0.0625; allow a tiny float epsilon.
assert abs(rlat - lat) <= 0.0625 + 1.0e-9
assert abs(rlon - lon) <= 0.0625 + 1.0e-9
end
end
end
describe "HrrrClient.nearest_hrrr_hour/1" do
property "is idempotent — once snapped, always snapped" do
check all(dt <- datetime_generator()) do
once = HrrrClient.nearest_hrrr_hour(dt)
twice = HrrrClient.nearest_hrrr_hour(once)
assert DateTime.compare(once, twice) == :eq
end
end
property "output is always exactly on the hour" do
check all(dt <- datetime_generator()) do
result = HrrrClient.nearest_hrrr_hour(dt)
assert result.minute == 0
assert result.second == 0
end
end
property "output is at or before the input by at most one hour" do
check all(dt <- datetime_generator()) do
result = HrrrClient.nearest_hrrr_hour(dt)
# Round-down only — the result is always the published cycle
# at or before `dt`, never a future cycle that may not exist.
delta_sec = DateTime.diff(dt, result, :second)
assert delta_sec >= 0
assert delta_sec < 60 * 60
end
end
property "always rounds down (never points at a future cycle)" do
check all(dt <- datetime_generator(minute_range: 30..59)) do
result = HrrrClient.nearest_hrrr_hour(dt)
# result is strictly before the input — the input minute > 0
# ensures a non-zero offset.
assert DateTime.before?(result, dt)
assert result.hour == dt.hour
end
end
end
describe "NexradClient.round_to_5min/1" do
property "is idempotent" do
check all(dt <- datetime_generator()) do
once = NexradClient.round_to_5min(dt)
twice = NexradClient.round_to_5min(once)
assert DateTime.compare(once, twice) == :eq
end
end
property "output minute is a multiple of 5" do
check all(dt <- datetime_generator()) do
result = NexradClient.round_to_5min(dt)
assert rem(result.minute, 5) == 0
assert result.second == 0
end
end
property "output is never later than the input (floor, not round)" do
check all(dt <- datetime_generator()) do
result = NexradClient.round_to_5min(dt)
assert DateTime.compare(result, dt) in [:lt, :eq]
end
end
property "output is within 5 minutes of input" do
check all(dt <- datetime_generator()) do
result = NexradClient.round_to_5min(dt)
delta_sec = DateTime.diff(dt, result, :second)
assert delta_sec >= 0
assert delta_sec < 5 * 60
end
end
end
describe "NarrClient.snap_to_analysis_hour/1" do
property "is idempotent" do
check all(dt <- datetime_generator()) do
once = NarrClient.snap_to_analysis_hour(dt)
twice = NarrClient.snap_to_analysis_hour(once)
assert DateTime.compare(once, twice) == :eq
end
end
property "output hour is in {0, 3, 6, 9, 12, 15, 18, 21}" do
check all(dt <- datetime_generator()) do
result = NarrClient.snap_to_analysis_hour(dt)
assert result.hour in [0, 3, 6, 9, 12, 15, 18, 21]
assert result.minute == 0
assert result.second == 0
end
end
property "output is never later than the input (floors to slot)" do
check all(dt <- datetime_generator()) do
result = NarrClient.snap_to_analysis_hour(dt)
assert DateTime.compare(result, dt) in [:lt, :eq]
end
end
property "output is within 3 hours of input" do
check all(dt <- datetime_generator()) do
result = NarrClient.snap_to_analysis_hour(dt)
delta_sec = DateTime.diff(dt, result, :second)
assert delta_sec >= 0
assert delta_sec < 3 * 3600
end
end
end
describe "NarrClient.in_coverage?/1" do
property "coverage_end is the first excluded timestamp (exclusive upper bound)" do
coverage_end = NarrClient.coverage_end()
refute NarrClient.in_coverage?(coverage_end)
one_sec_before = DateTime.shift(coverage_end, second: -1)
assert NarrClient.in_coverage?(one_sec_before)
end
property "any DateTime after coverage_end is out of coverage" do
coverage_end = NarrClient.coverage_end()
check all(seconds_after <- integer(1..100_000_000)) do
dt = DateTime.shift(coverage_end, second: seconds_after)
refute NarrClient.in_coverage?(dt)
end
end
end
# Generate DateTimes across the HRRR archive era. Avoiding DST
# discontinuities and month-boundary edge cases by staying well inside
# a single month — snap_to_analysis_hour / nearest_hrrr_hour are
# purely field-arithmetic on the DateTime struct, so this is enough
# to exercise every branch.
defp datetime_generator(opts \\ []) do
minute_range = Keyword.get(opts, :minute_range, 0..59)
gen all(
year <- integer(2019..2030),
month <- integer(1..12),
day <- integer(1..28),
hour <- integer(0..23),
minute <- integer(minute_range),
second <- integer(0..59)
) do
%DateTime{
year: year,
month: month,
day: day,
hour: hour,
minute: minute,
second: second,
microsecond: {0, 0},
std_offset: 0,
utc_offset: 0,
zone_abbr: "UTC",
time_zone: "Etc/UTC"
}
end
end
end