Bugfix webmercator X check (#44)

* extent 1 and 2 can be equal

* test equal x

src/tiles.jl

@@ -122,7 +122,7 @@ function TileGrid(bbox::Extent, zoom::Int, crs::WGS84)
     # Mercantile splits the bbox in two along the antimeridian if this happens.
     # Decide if that case should be handled here or before, also considering
     # antimeridian discussion in https://github.com/rafaqz/Extents.jl/issues/4
-    @assert bbox.X[1] < bbox.X[2]
+    @assert bbox.X[1] <= bbox.X[2]
 
     # Clamp bounding values.
     max_bbox = Extent(X = (-180.0, 180.0), Y = (-85.051129, 85.051129))

test/runtests.jl

@@ -45,6 +45,11 @@ end
     # creating a TileGrid from a web mercator extent
     webbox = MT.project_extent(bbox, MT.wgs84, MT.web_mercator)
     @test tilegrid === TileGrid(webbox, 8, MT.web_mercator)
+
+    @testset "equal X works" begin
+        bbox = Extent(X = (-1.23, -1.23), Y = (-5.68, 4.77))
+        @test_nowarn tilegrid = TileGrid(bbox, 8, MT.web_mercator)
+    end
 end
 
 @testset "project" begin