test: add network and orchestration unit tests for stations, download…

[jsteinberg34]

Summary

Phase 4 of the test suite: the acquisition + orchestration layer. Phases 1–3 cover the deterministic/network-free code; this adds coverage for stations.py, download.py, the Space-Track network branch of track.py, and run_pipeline. The genuinely network-bound seams (FDSN Client/MassDownloader, Space-Track) are replaced with fakes, so everything runs deterministically with no network.

What's new

• tests/test_stations.py — all of stations.py (network-free): StationXML discovery, parsing (incl. skip-on-corrupt-file), dedup, corridor distance filter with min_dist_km, longitude wrapping, and the load_and_filter_stations end-to-end chain.
• tests/test_download.py — pure helpers (_normalize_providers, _count_files, the _make_mseed_storage approval gate) plus download_boxes driven with faked Client/MassDownloader: happy path (candidate → dedup → corridor filter → download → manifest), skip-existing, apply_processing hand-off, all-stations-rejected, and resilience (provider-init / get_stations no-data + generic / downloader errors all tolerated).
• tests/test_track.py — adds the Space-Track network branch via a faked client: fetch_tle_best_before_cached cache-miss (query + cache write) and build_track_from_norad end-to-end (faked TLE → real offline propagation).
• tests/test_pipeline.py — run_pipeline with both heavy stages spied: verifies ISO-string→UTC parsing, that the real tiling stage runs and feeds the download requests, and the {track, boxes, manifest} return shape.
• tests/conftest.py — adds FakeFDSNClient, FakeMassDownloader (drives the real storage callback and writes files), and FakeSpaceTrack; makes the synthetic-inventory builder reusable with lat/lon. Additive only.

Coverage

Module	Coverage
stations.py	100%
track.py	88%
download.py	85%
pipeline.py	85%

Remaining misses in these modules are verbose=True logging lines — every logic branch is covered. plotting.py is the only module still untested (Phase 5).

Testing

pytest          # 112 passed, fully offline

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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