Delegate `Column#type` to the injected type object

The decision to wrap type registrations in a proc was made for two
reasons.

1. Some cases need to make an additional decision based on the type
  (e.g. a `Decimal` with a 0 scale)
2. Aliased types are automatically updated if they type they point to is
  updated later. If a user or another adapter decides to change the
  object used for `decimal` columns, `numeric`, and `number` will
  automatically point to the new type, without having to track what
  types are aliased explicitly.

Everything else here should be pretty straightforward. PostgreSQL ranges
had to change slightly, since the `simplified_type` method is gone.

1 files changed, 102 insertions, 0 deletions

diff --git a/activerecord/test/cases/connection_adapters/type/type_map_test.rb b/activerecord/test/cases/connection_adapters/type/type_map_test.rb
new file mode 100644
index 0000000000..565f44eef8
--- /dev/null
+++ b/activerecord/test/cases/connection_adapters/type/type_map_test.rb
@@ -0,0 +1,102 @@
+require "cases/helper"
+
+module ActiveRecord
+  module ConnectionAdapters
+    module Type
+      class TypeMapTest < ActiveRecord::TestCase
+        def test_default_type
+          mapping = TypeMap.new
+
+          assert_kind_of Value, mapping.lookup(:undefined)
+        end
+
+        def test_registering_types
+          boolean = Boolean.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/boolean/i, boolean)
+
+          assert_equal mapping.lookup('boolean'), boolean
+        end
+
+        def test_overriding_registered_types
+          time = Time.new
+          timestamp = Timestamp.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/time/i, time)
+          mapping.register_type(/time/i, timestamp)
+
+          assert_equal mapping.lookup('time'), timestamp
+        end
+
+        def test_fuzzy_lookup
+          string = String.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/varchar/i, string)
+
+          assert_equal mapping.lookup('varchar(20)'), string
+        end
+
+        def test_aliasing_types
+          string = String.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/string/i, string)
+          mapping.alias_type(/varchar/i, 'string')
+
+          assert_equal mapping.lookup('varchar'), string
+        end
+
+        def test_changing_type_changes_aliases
+          time = Time.new
+          timestamp = Timestamp.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/timestamp/i, time)
+          mapping.alias_type(/datetime/i, 'timestamp')
+          mapping.register_type(/timestamp/i, timestamp)
+
+          assert_equal mapping.lookup('datetime'), timestamp
+        end
+
+        def test_aliases_keep_metadata
+          mapping = TypeMap.new
+
+          mapping.register_type(/decimal/i) { |sql_type| sql_type }
+          mapping.alias_type(/number/i, 'decimal')
+
+          assert_equal mapping.lookup('number(20)'), 'decimal(20)'
+          assert_equal mapping.lookup('number'), 'decimal'
+        end
+
+        def test_register_proc
+          string = String.new
+          binary = Binary.new
+          mapping = TypeMap.new
+
+          mapping.register_type(/varchar/i) do |type|
+            if type.include?('(')
+              string
+            else
+              binary
+            end
+          end
+
+          assert_equal mapping.lookup('varchar(20)'), string
+          assert_equal mapping.lookup('varchar'), binary
+        end
+
+        def test_requires_value_or_block
+          mapping = TypeMap.new
+
+          assert_raises(ArgumentError) do
+            mapping.register_type(/only key/i)
+          end
+        end
+      end
+    end
+  end
+end
+