PostgreSQL determine `Column#type` through corresponding OID. #7814

I ran the whole test suite and compared the old to the new types.
Following is the list of types that did change with this patch:

```
DIFFERENT TYPE FOR mood: NEW: enum, BEFORE:
DIFFERENT TYPE FOR floatrange: NEW: floatrange, BEFORE: float
```

The `floatrange` is a custom type. The old type `float` was simply a coincidence
form the name `floatrange` and our type-guessing.

3 files changed, 5 insertions, 6 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/enum_test.rb b/activerecord/test/cases/adapters/postgresql/enum_test.rb
index 381c397922..ac78c2426e 100644
--- a/activerecord/test/cases/adapters/postgresql/enum_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/enum_test.rb
@@ -29,8 +29,7 @@ class PostgresqlEnumTest < ActiveRecord::TestCase
 
   def test_column
     column = PostgresqlEnum.columns_hash["current_mood"]
-    # TODO: enum columns should be of type enum or string, not nil.
-    assert_nil column.type
+    assert_equal :enum, column.type
     assert_equal "mood", column.sql_type
     assert_not column.number?
     assert_not column.text?
diff --git a/activerecord/test/cases/adapters/postgresql/quoting_test.rb b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
index 39f5b9b18a..51846e22d9 100644
--- a/activerecord/test/cases/adapters/postgresql/quoting_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
@@ -47,9 +47,9 @@ module ActiveRecord
 
         def test_quote_cast_numeric
           fixnum = 666
-          c = PostgreSQLColumn.new(nil, nil, OID::Decimal.new, 'varchar')
+          c = PostgreSQLColumn.new(nil, nil, OID::String.new, 'varchar')
           assert_equal "'666'", @conn.quote(fixnum, c)
-          c = PostgreSQLColumn.new(nil, nil, OID::Decimal.new, 'text')
+          c = PostgreSQLColumn.new(nil, nil, OID::Text.new, 'text')
           assert_equal "'666'", @conn.quote(fixnum, c)
         end
 
diff --git a/activerecord/test/cases/column_definition_test.rb b/activerecord/test/cases/column_definition_test.rb
index c7b64f29c3..c1dd1f1c69 100644
--- a/activerecord/test/cases/column_definition_test.rb
+++ b/activerecord/test/cases/column_definition_test.rb
@@ -127,13 +127,13 @@ module ActiveRecord
 
       if current_adapter?(:PostgreSQLAdapter)
         def test_bigint_column_should_map_to_integer
-          oid = PostgreSQLAdapter::OID::Identity.new
+          oid = PostgreSQLAdapter::OID::Integer.new
           bigint_column = PostgreSQLColumn.new('number', nil, oid, "bigint")
           assert_equal :integer, bigint_column.type
         end
 
         def test_smallint_column_should_map_to_integer
-          oid = PostgreSQLAdapter::OID::Identity.new
+          oid = PostgreSQLAdapter::OID::Integer.new
           smallint_column = PostgreSQLColumn.new('number', nil, oid, "smallint")
           assert_equal :integer, smallint_column.type
         end