Make sure all lines in a MultiLineString are valid

Note we're starting to use hashes in tests because the objects here are
complex and using hashes makes the tests easier to read.

app/models/concerns/geojson_format_validator.rb

@@ -80,10 +80,14 @@ class GeojsonFormatValidator < ActiveModel::EachValidator
       when "Point"
         valid_wgs84_coordinates?(coordinates)
       when "LineString"
-        coordinates.many? && valid_coordinates_array?(coordinates)
+        valid_linestring_coordinates?(coordinates)
       when "MultiPoint"
         valid_coordinates_array?(coordinates)
-      when "Polygon", "MultiLineString"
+      when "MultiLineString"
+        coordinates.all? do |linestring_coordinates|
+          valid_linestring_coordinates?(linestring_coordinates)
+        end
+      when "Polygon"
         valid_polygon_coordinates?(coordinates)
       when "MultiPolygon"
         coordinates.all? do |polygon_coordinates|
@@ -102,9 +106,14 @@ class GeojsonFormatValidator < ActiveModel::EachValidator
     end
 
     def valid_coordinates_array?(coordinates_array)
+      coordinates_array.is_a?(Array) &&
         coordinates_array.all? { |coordinates| valid_wgs84_coordinates?(coordinates) }
     end
 
+    def valid_linestring_coordinates?(coordinates)
+      valid_coordinates_array?(coordinates) && coordinates.many?
+    end
+
     def valid_polygon_coordinates?(polygon_coordinates)
       polygon_coordinates.all? do |ring_coordinates|
         valid_coordinates_array?(ring_coordinates)

spec/models/geojson_format_validator_spec.rb

@@ -159,6 +159,64 @@ describe GeojsonFormatValidator do
     end
   end
 
+  context "Polygon or MultiLineString geometry" do
+    it "is not valid with a one-dimensional array of coordinates" do
+      record.geojson = '{ "type": "MultiLineString", "coordinates": [1.23, 4.56] }'
+
+      expect(record).not_to be_valid
+
+      record.geojson = '{ "type": "Polygon", "coordinates": [1.23, 4.56] }'
+
+      expect(record).not_to be_valid
+    end
+
+    it "is not valid with a two-dimensional array of coordinates" do
+      record.geojson = '{ "type": "MultiLineString", "coordinates": [[1.23, 4.56], [7.89, 4.56]] }'
+
+      expect(record).not_to be_valid
+
+      record.geojson = '{ "type": "Polygon", "coordinates": [[1.23, 4.56], [7.89, 4.56]] }'
+
+      expect(record).not_to be_valid
+    end
+  end
+
+  context "MultiLineString geometry" do
+    it "is valid with just one line" do
+      record.geojson = '{ "type": "MultiLineString", "coordinates": [[[1.23, 4.56], [7.89, 4.56]]] }'
+
+      expect(record).to be_valid
+    end
+
+    it "is valid with multiple valid lines" do
+      record.geojson = <<~JSON
+        {
+          "type": "MultiLineString",
+          "coordinates": [
+            [[1.23, 4.56], [7.89, 4.56]],
+            [[10.11, 12.13], [14.15, 16.17]]
+          ]
+        }
+      JSON
+
+      expect(record).to be_valid
+    end
+
+    it "is not valid if some lines are invalid" do
+      record.geojson = <<~JSON
+        {
+          "type": "MultiLineString",
+          "coordinates": [
+            [[1.23, 4.56], [7.89, 4.56]],
+            [[10.11, 12.13]]
+          ]
+        }
+      JSON
+
+      expect(record).not_to be_valid
+    end
+  end
+
   context "GeometryCollection" do
     it "is not valid if it doesn't contain geometries" do
       record.geojson = '{ "type": "GeometryCollection" }'