Use the Extents.jl interface, rather than old GI (#95)

* update to use Extents interface rather than old GI

* Add tests for extents where `bbox` does not exist

src/geointerface.jl

@@ -57,12 +57,8 @@ GI.getfeature(::GI.FeatureCollectionTrait, fc::AbstractFeatureCollection, i::Int
 GI.nfeature(::GI.FeatureCollectionTrait, fc::AbstractFeatureCollection) = length(fc)
 
 # Any GeoJSON Object
-GI.extent(::GI.FeatureTrait, x::GeoJSONT{2}) = _extent2(x)
-GI.extent(::GI.FeatureCollectionTrait, x::GeoJSONT{2}) = _extent2(x)
-GI.extent(::GI.AbstractGeometryTrait, x::GeoJSONT{2}) = _extent2(x)
-GI.extent(::GI.FeatureTrait, x::GeoJSONT{3}) = _extent3(x)
-GI.extent(::GI.FeatureCollectionTrait, x::GeoJSONT{3}) = _extent3(x)
-GI.extent(::GI.AbstractGeometryTrait, x::GeoJSONT{3}) = _extent3(x)
+GI.Extents.extent(x::GeoJSONT{2}) = _extent2(x)
+GI.Extents.extent(x::GeoJSONT{3}) = _extent3(x)
 
 function _extent3(x)
     bb = bbox(x)

test/runtests.jl

@@ -321,6 +321,14 @@ include("geojson_samples.jl")
         end
     end
 
+    @testset "Extents" begin
+        # First, test that `Extents.extent` returns nothing for a geometry with no bbox
+        feature = GeoJSON.read(Samples.b)
+        @test isnothing(GI.Extents.extent(feature))
+        # Next, test that `GI.extent` returns the correct extent for a geometry with a bbox
+        @test GI.extent(feature) == mapreduce(GI.extent, GI.Extents.union, GI.getpoint(feature.geometry))
+    end
+
     @testset "GeoInterface tests" begin
         @test all(GI.testgeometry, GeoJSON.read.(Samples.geometries))
         @test all(GI.testfeature, GeoJSON.read.(Samples.features))