Graham McIntire
b7e19e18cc
First slice of the NARR backfill client: url_for/1, url_for_inventory/1, and snap_to_analysis_hour/1. Pure functions, no network. Validates that NARR analyses only exist at 3-hourly slots (00/03/06/09/12/15/18/21 UTC). The byte-range fetch and cdo-driven point extraction land in follow-up commits per docs/plans/2026-04-15-merra2-historical-backfill.md.
76 lines
2.6 KiB
Elixir
76 lines
2.6 KiB
Elixir
defmodule Microwaveprop.Weather.NarrClientTest do
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use ExUnit.Case, async: true
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alias Microwaveprop.Weather.NarrClient
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describe "url_for/1" do
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test "builds the NCEI NARR HTTPS URL for a 3-hourly analysis time" do
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vt = ~U[2010-06-15 12:00:00Z]
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assert NarrClient.url_for(vt) ==
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"https://www.ncei.noaa.gov/data/north-american-regional-reanalysis/access/3-hourly/201006/20100615/narr-a_221_20100615_1200_000.grb"
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end
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test "uses zero-padded HHMM for off-hour analyses" do
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vt = ~U[2010-06-15 03:00:00Z]
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assert NarrClient.url_for(vt) ==
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"https://www.ncei.noaa.gov/data/north-american-regional-reanalysis/access/3-hourly/201006/20100615/narr-a_221_20100615_0300_000.grb"
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end
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test "raises ArgumentError on non-3-hourly hours" do
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assert_raise ArgumentError, fn ->
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NarrClient.url_for(~U[2010-06-15 13:00:00Z])
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end
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end
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test "raises ArgumentError when minutes are non-zero" do
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assert_raise ArgumentError, fn ->
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NarrClient.url_for(~U[2010-06-15 12:30:00Z])
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end
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end
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end
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describe "url_for_inventory/1" do
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test "swaps .grb for .inv" do
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vt = ~U[2010-06-15 12:00:00Z]
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assert NarrClient.url_for_inventory(vt) ==
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"https://www.ncei.noaa.gov/data/north-american-regional-reanalysis/access/3-hourly/201006/20100615/narr-a_221_20100615_1200_000.inv"
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end
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end
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describe "snap_to_analysis_hour/1" do
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test "rounds down to the nearest 3-hourly NARR slot" do
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 13:42:00Z]) ==
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~U[2010-06-15 12:00:00Z]
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 14:30:00Z]) ==
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~U[2010-06-15 12:00:00Z]
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 15:00:00Z]) ==
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~U[2010-06-15 15:00:00Z]
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 23:59:59Z]) ==
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~U[2010-06-15 21:00:00Z]
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 00:00:00Z]) ==
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~U[2010-06-15 00:00:00Z]
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 02:00:00Z]) ==
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~U[2010-06-15 00:00:00Z]
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end
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test "preserves the date when snapping doesn't cross midnight" do
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assert NarrClient.snap_to_analysis_hour(~U[2010-06-15 05:17:42Z]) ==
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~U[2010-06-15 03:00:00Z]
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end
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test "snaps minutes and seconds to zero" do
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snapped = NarrClient.snap_to_analysis_hour(~U[2010-06-15 13:42:37Z])
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assert snapped.minute == 0
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assert snapped.second == 0
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assert snapped.microsecond == {0, 0}
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end
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end
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end
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