Fix Decimal type when precision and scale are unspecified

lib/active_record/connection_adapters/cockroachdb_adapter.rb

@@ -98,7 +98,7 @@ class CockroachDBAdapter < PostgreSQLAdapter
           st_polygon:          {},
         }
 
-      # http://postgis.17.x6.nabble.com/Default-SRID-td5001115.html      
+      # http://postgis.17.x6.nabble.com/Default-SRID-td5001115.html
       DEFAULT_SRID = 0
 
       include CockroachDB::SchemaStatements
@@ -272,12 +272,9 @@ def initialize_type_map(m = type_map)
             precision = extract_precision(sql_type)
             scale = extract_scale(sql_type)
 
-            # TODO(#178) this should never use DecimalWithoutScale since scale
-            # is assumed to be 0 if it is not explicitly defined.
-            #
             # If fmod is -1, that means that precision is defined but not
             # scale, or neither is defined.
-            if fmod && fmod == -1
+            if fmod && fmod == -1 && !precision.nil?
               # Below comment is from ActiveRecord
               # FIXME: Remove this class, and the second argument to
               # lookups on PG
@@ -390,7 +387,7 @@ def extract_time_from_default(default)
         # In general, it is hard to parse that, but it is easy to handle the common
         # case of an empty array.
         def extract_empty_array_from_default(default)
-          return unless supports_string_to_array_coercion? 
+          return unless supports_string_to_array_coercion?
           return unless default =~ /\AARRAY\[\]\z/
           return "{}"
         end

test/cases/adapters/postgresql/numeric_test.rb

@@ -0,0 +1,28 @@
+require "cases/helper_cockroachdb"
+
+# Load dependencies from ActiveRecord test suite
+require "support/schema_dumping_helper"
+
+module CockroachDB
+  class PostgresqlNumberTest < ActiveRecord::PostgreSQLTestCase
+    include SchemaDumpingHelper
+
+    class PostgresqlNumber < ActiveRecord::Base; end
+
+    setup do
+      @connection = ActiveRecord::Base.connection
+      @connection.create_table("postgresql_numbers", force: true) do |t|
+        t.decimal 'decimal_default'
+      end
+    end
+
+    teardown do
+      @connection.drop_table "postgresql_decimals", if_exists: true
+    end
+
+    def test_decimal_values
+      record = PostgresqlNumber.new(decimal_default: 111.222)
+      assert_equal record.decimal_default, 111.222
+    end
+  end
+end