Fix SchemaStatements#initialize_type_map

Since the Rails 6 upgrade, we started seeing some random PostGIS type
issues on our staging env, while we don't know yet why our production env
doesn't seem to be affected, debugging the issue on staging shows that the
ActiveRecord connection `type_map` isn't initialized properly which leave the
custom `ActiveRecord::ConnectionAdapters::PostGIS::SpatialColumn` without
a defined type, while usually, the type is lazy loaded correctly later on
by  `PostgreSQLAdapter#get_oid_type` it could happen that the
`ModelSchema#load_schema!` method is called first which will define and
cache the attribute type (`@attribute_types`) with the wrong
default value type (`ActiveModel::Type::Value`) `type_cast` using the
`lookup_cast_type_from_column` method that reads straight from the
 `type_map` cache without lazy loading the type. The wrong type is
then always returned for that column which brakes all the casting logic.

This patch fixes the `SchemaStatements#initialize_type_map`
method by ensuring that the specific PostGIS types are registered before
calling `super` which will then call `load_additional_types` and registers
the custom types. That way the custom column will be properly initialized
and be present in the `type_map` cache.

Some code references:
 - The `initialize_type_map` activerecord-postgis-adapter method overwritten https://github.com/rgeo/activerecord-postgis-adapter/blob/cc0e3f53520feed0b43800d8ee86561ee03de413/lib/active_record/connection_adapters/postgis/schema_statements.rb#L87-L105
 - the `load_additional_types` method in Rails: https://github.com/rails/rails/blob/8d57cb39a88787bb6cfb7e1c481556ef6d8ede7a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb#L593
 - the `get_oid_type` method in Rails that lazy load the type: https://github.com/rails/rails/blob/8d57cb39a88787bb6cfb7e1c481556ef6d8ede7a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb#L514-L516
 - the `lookup_cast_type_from_column` method in Rails that does not lazy load the type: https://github.com/rails/rails/blob/15748f6a052d4df68b6acf66456c181b42d9fe25/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb#L78

This patch should solve rgeo#307 and rgeo#308.

CONTRIBUTING.md

@@ -43,7 +43,7 @@ run `rake appraisal` or run the tests manually:
 
 ```
 BUNDLE_GEMFILE=./gemfiles/ar60.gemfile bundle
-BUNDLE_GEMFILE=./gemfiles/ar60.gemfile rake
+BUNDLE_GEMFILE=./gemfiles/ar60.gemfile bundle exec rake
 ```
 
 Make your changes and submit a pull request.

lib/active_record/connection_adapters/postgis/schema_statements.rb

@@ -85,8 +85,6 @@ def spatial_column_info(table_name)
         end
 
         def initialize_type_map(map = type_map)
-          super
-
           %w(
             geography
             geometry
@@ -102,6 +100,8 @@ def initialize_type_map(map = type_map)
               OID::Spatial.new(oid, sql_type)
             end
           end
+
+          super
         end
       end
     end

test/schema_statements_test.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class SchemaStatementsTest < ActiveSupport::TestCase
+  def test_initialize_type_map
+    initialized_types = SpatialModel.connection.send(:type_map).keys
+
+    # PostGIS types must be initialized first, so
+    # ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#load_additional_types can use them
+    # https://github.com/rails/rails/blob/8d57cb39a88787bb6cfb7e1c481556ef6d8ede7a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb#L593
+    assert_equal initialized_types.first(9), %w[
+      geography
+      geometry
+      geometry_collection
+      line_string
+      multi_line_string
+      multi_point
+      multi_polygon
+      st_point
+      st_polygon
+    ]
+  end
+end