test: Add unit tests for geo utility functions

[Vishmayraj]

geo_utils.go had no test coverage. This PR adds geo_utils_test.go
covering:

• computeBoundingBox: empty input, nil coordinates, single stop,
  multiple stops, mixed valid/nil coordinates
• isValidLatLon: zero coordinates, valid coordinates, boundary values,
  out-of-range values
• BoundingBoxStore: set/get, nonexistent server, point inside/outside
  bounding box
• haversineDistance: same point, known real-world distance

All existing tests continue to pass.

[0xaboomar]

Hi @Vishmayraj , thanks for the PR and the work you’ve put into this.

I’ve left a few comments and requested some changes that should be addressed before we proceed with merging. Please take a look and let me know once they’re updated.

[0xaboomar]

The current 50km margin is a bit too loose. The theoretical maximum error for spherical approximations (like Haversine) is roughly 0.5%, which equates to ~19km for this Seattle-to-NY distance.

I suggest tightening the margin to 25km. This is wide enough to cover the 0.5% model discrepancy while being significantly more precise than 50km.

Look at the "Accuracy" note in this source for more details: https://www.movable-type.co.uk/scripts/latlong.html

[0xaboomar]

I recommend removing the header comment block (including the Author tag and test instructions). In Go, the filename and the tests themselves should be self-documenting, and Git handles the authorship tracking. This will keep the file cleaner.

[0xaboomar]

I suggest adding checks for MinLon and MaxLon as well.

[0xaboomar]

Since these geographic tests are primarily mathematical and completely independent, I suggest adding t.Parallel() to the top of each test function and subtest (t.Run).

[aaronbrethorst]

Code review

Found 1 issue:

1. The test file imports github.com/jamespfennell/gtfs, which is no longer a dependency of this module. main migrated the GTFS parser to github.com/OneBusAway/go-gtfs in Migrate to oba gtfs #93 (commit 1dabe72); go.mod now lists only github.com/OneBusAway/go-gtfs v1.1.1 and go.sum has no jamespfennell entries at all. As written the package will not build on current main — and even if the old module were re-added, []jamespfennell/gtfs.Stop is a distinct named type from the []OneBusAway/go-gtfs.Stop that computeBoundingBox accepts, so TestComputeBoundingBox would still fail to typecheck. Worth calling out explicitly because GitHub reports this PR as mergeable/clean: the Go workflow has never run on the head commit (only the CLA check is present), so nothing here will surface the break before it lands on main. Rebasing on main and switching the import to remoteGtfs "github.com/OneBusAway/go-gtfs" should be all that is needed — @0xaboomar's guidance on Migrate to oba gtfs #93 was to keep the remoteGtfs alias and change only the module.

watchdog/internal/geo/geo_utils_test.go

Lines 14 to 18 in e1d26b3

	import (
	"testing"
	remoteGtfs "github.com/jamespfennell/gtfs"
	)

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}