samplez/rippr-flutter-src/test/tile_math_test.dart

import 'package:flutter_test/flutter_test.dart';
import 'package:rippr/src/geo/geo.dart' show LatLon;
import 'package:rippr/src/tiles/tile_math.dart';

void main() {
  group('tilesForBounds', () {
    test('a single point covers exactly one tile per zoom level', () {
      final tiles = tilesForBounds(
        minLat: 51.0,
        maxLat: 51.0,
        minLon: -114.0,
        maxLon: -114.0,
        minZoom: 10,
        maxZoom: 12,
      );
      // One tile at each of the three zoom levels.
      expect(tiles.length, 3);
      expect(tiles.map((t) => t.z).toSet(), {10, 11, 12});
    });

    test('the same box covers more tiles at a higher zoom', () {
      final low = tilesForBounds(
        minLat: 50.99,
        maxLat: 51.01,
        minLon: -114.01,
        maxLon: -113.99,
        minZoom: 10,
        maxZoom: 10,
      );
      final high = tilesForBounds(
        minLat: 50.99,
        maxLat: 51.01,
        minLon: -114.01,
        maxLon: -113.99,
        minZoom: 14,
        maxZoom: 14,
      );
      expect(high.length, greaterThan(low.length));
    });

    test('throws rather than silently truncating past the cap', () {
      expect(
        () => tilesForBounds(
          minLat: -80,
          maxLat: 80,
          minLon: -170,
          maxLon: 170,
          minZoom: 10,
          maxZoom: 14,
        ),
        throwsA(isA<TooManyTilesException>()),
      );
    });

    test('tiles are deduplicated across an overlapping request', () {
      final tiles = tilesForBounds(
        minLat: 51.0,
        maxLat: 51.001,
        minLon: -114.0,
        maxLon: -113.999,
        minZoom: 5,
        maxZoom: 5,
      );
      // A Set literally cannot contain a duplicate; this documents the intent that
      // adjacent/overlapping coverage collapses rather than being counted twice.
      expect(tiles.toSet().length, tiles.length);
    });
  });

  group('tilesAlongRoute', () {
    test('costs far less than the bounding-box rectangle for a route that '
        'zigzags across its own bounding box', () {
      // A route that ping-pongs in latitude while advancing in longitude -- its
      // bounding box is a full rectangle, but the corridor only has to cover the
      // narrow path actually ridden through that rectangle.
      final route = [
        for (var i = 0; i <= 40; i++)
          LatLon(51.0 + (i.isEven ? 0.0 : 0.3), -114.0 + i * 0.02),
      ];

      final corridor = tilesAlongRoute(
        route,
        minZoom: 12,
        maxZoom: 12,
        bufferMeters: 150,
      );
      final rectangle = tilesForBounds(
        minLat: 51.0,
        maxLat: 51.3,
        minLon: -114.0,
        maxLon: -113.2,
        minZoom: 12,
        maxZoom: 12,
      );

      expect(corridor.length, lessThan(rectangle.length),
          reason: 'the whole point of a corridor is fewer tiles than the bounding box');
    });

    test('an empty route needs no tiles', () {
      expect(tilesAlongRoute([], minZoom: 10, maxZoom: 12), isEmpty);
    });

    test('throws past the cap, same as tilesForBounds', () {
      final route = [for (var i = 0; i < 500; i++) LatLon(i * 0.1 - 25, i * 0.1 - 25)];
      expect(
        () => tilesAlongRoute(route, minZoom: 12, maxZoom: 14, bufferMeters: 500),
        throwsA(isA<TooManyTilesException>()),
      );
    });
  });

  group('estimatedSizeMb', () {
    test('scales linearly with tile count', () {
      expect(estimatedSizeMb(0), 0);
      expect(estimatedSizeMb(1024, avgTileSizeKb: 1), closeTo(1.0, 1e-9));
    });
  });
}