Validate MapLocation lat/long/zoom have numeric values

app/models/map_location.rb

@@ -3,7 +3,7 @@ class MapLocation < ActiveRecord::Base
   belongs_to :proposal, touch: true
   belongs_to :investment, class_name: Budget::Investment, touch: true
 
-  validates :longitude, :latitude, :zoom, presence: true
+  validates :longitude, :latitude, :zoom, presence: true, numericality: true
 
   def available?
     latitude.present? && longitude.present? && zoom.present?

spec/models/map_location_spec.rb

@@ -13,6 +13,15 @@ describe MapLocation do
     map_location.latitude = nil
     map_location.zoom = nil
 
+    expect(map_location).not_to be_valid
+    expect(map_location.errors.size).to eq(6)
+  end
+
+  it "is invalid when longitude/latitude/zoom are not numbers" do
+    map_location.longitude = 'wadus'
+    map_location.latitude = 'stuff'
+    map_location.zoom = '$%·'
+
     expect(map_location).not_to be_valid
     expect(map_location.errors.size).to eq(3)
   end