Revert "test pg, we don't care about the internal state of `column#default`."

Revert "test pg, remove unused column assignments. Follow up to 254cdf47"

Related to #15492

This reverts commit 254cdf47.
This reverts commit 4bcf9029.

There are public methods that assume `Column#default` is type casted.
The return value of `Column#default` is publicly relevant and should not change.

/cc @sgrif

activerecord/test/cases/adapters/postgresql/array_test.rb

@@ -38,6 +38,9 @@ def test_column
   def test_default
     @connection.add_column 'pg_arrays', 'score', :integer, array: true, default: [4, 4, 2]
     PgArray.reset_column_information
+    column = PgArray.columns_hash["score"]
+
+    assert_equal([4, 4, 2], column.default)
     assert_equal([4, 4, 2], PgArray.new.score)
   ensure
     PgArray.reset_column_information
@@ -48,6 +51,7 @@ def test_default_strings
     PgArray.reset_column_information
     column = PgArray.columns_hash["names"]
 
+    assert_equal(["foo", "bar"], column.default)
     assert_equal(["foo", "bar"], PgArray.new.names)
   ensure
     PgArray.reset_column_information

activerecord/test/cases/adapters/postgresql/bit_string_test.rb

@@ -42,7 +42,12 @@ def test_bit_string_varying_column
   end
 
   def test_default
+    column = PostgresqlBitString.columns_hash["a_bit"]
+    assert_equal "00000011", column.default
     assert_equal "00000011", PostgresqlBitString.new.a_bit
+
+    column = PostgresqlBitString.columns_hash["a_bit_varying"]
+    assert_equal "0011", column.default
     assert_equal "0011", PostgresqlBitString.new.a_bit_varying
   end
 

activerecord/test/cases/adapters/postgresql/enum_test.rb

@@ -44,6 +44,7 @@ def test_enum_defaults
     PostgresqlEnum.reset_column_information
     column = PostgresqlEnum.columns_hash["good_mood"]
 
+    assert_equal "happy", column.default
     assert_equal "happy", PostgresqlEnum.new.good_mood
   ensure
     PostgresqlEnum.reset_column_information

activerecord/test/cases/adapters/postgresql/geometric_test.rb

@@ -35,7 +35,12 @@ def test_column
   end
 
   def test_default
+    column = PostgresqlPoint.columns_hash["y"]
+    assert_equal [12.2, 13.3], column.default
     assert_equal [12.2, 13.3], PostgresqlPoint.new.y
+
+    column = PostgresqlPoint.columns_hash["z"]
+    assert_equal [14.4, 15.5], column.default
     assert_equal [14.4, 15.5], PostgresqlPoint.new.z
   end
 

activerecord/test/cases/adapters/postgresql/hstore_test.rb

@@ -64,6 +64,9 @@ def test_column
     def test_default
       @connection.add_column 'hstores', 'permissions', :hstore, default: '"users"=>"read", "articles"=>"write"'
       Hstore.reset_column_information
+      column = Hstore.columns_hash["permissions"]
+
+      assert_equal({"users"=>"read", "articles"=>"write"}, column.default)
       assert_equal({"users"=>"read", "articles"=>"write"}, Hstore.new.permissions)
     ensure
       Hstore.reset_column_information

activerecord/test/cases/adapters/postgresql/json_test.rb

@@ -43,6 +43,9 @@ def test_column
   def test_default
     @connection.add_column 'json_data_type', 'permissions', :json, default: '{"users": "read", "posts": ["read", "write"]}'
     JsonDataType.reset_column_information
+    column = JsonDataType.columns_hash["permissions"]
+
+    assert_equal({"users"=>"read", "posts"=>["read", "write"]}, column.default)
     assert_equal({"users"=>"read", "posts"=>["read", "write"]}, JsonDataType.new.permissions)
   ensure
     JsonDataType.reset_column_information

activerecord/test/cases/adapters/postgresql/money_test.rb

@@ -32,6 +32,8 @@ def test_column
   end
 
   def test_default
+    column = PostgresqlMoney.columns_hash["depth"]
+    assert_equal BigDecimal.new("150.55"), column.default
     assert_equal BigDecimal.new("150.55"), PostgresqlMoney.new.depth
   end