Normalize date component when writing to time columns

For legacy reasons Rails stores time columns on sqlite as full
timestamp strings. However because the date component wasn't being
normalized this meant that when they were read back they were being
prefixed with 2001-01-01 by ActiveModel::Type::Time. This had a
twofold result - first it meant that the fast code path wasn't being
used because the string was invalid and second it was corrupting the
second fractional component being read by the Date._parse code path.

Fix this by a combination of normalizing the timestamps on writing
and also changing Active Model to be more lenient when detecting
whether a string starts with a date component before creating the
dummy time value for parsing.

activemodel/lib/active_model/type/time.rb

@@ -31,11 +31,7 @@ module ActiveModel
           return apply_seconds_precision(value) unless value.is_a?(::String)
           return if value.empty?
 
-          if value.start_with?("2000-01-01")
-            dummy_time_value = value
-          else
-            dummy_time_value = "2000-01-01 #{value}"
-          end
+          dummy_time_value = value.sub(/\A(\d\d\d\d-\d\d-\d\d |)/, "2000-01-01 ")
 
           fast_string_to_time(dummy_time_value) || begin
             time_hash = ::Date._parse(dummy_time_value)

activerecord/lib/active_record/connection_adapters/sqlite3/quoting.rb

@@ -17,7 +17,7 @@ module ActiveRecord
         end
 
         def quoted_time(value)
-          quoted_date(value)
+          quoted_date(value).sub(/\A\d\d\d\d-\d\d-\d\d /, "2000-01-01 ")
         end
 
         def quoted_binary(value)

activerecord/test/cases/adapters/sqlite3/quoting_test.rb

@@ -55,4 +55,11 @@ class SQLite3QuotingTest < ActiveRecord::SQLite3TestCase
 
     assert_equal "'2000-01-01 12:30:00.999999'", @conn.quote(type.serialize(value))
   end
+
+  def test_quoted_time_normalizes_date_qualified_time
+    value = ::Time.utc(2018, 3, 11, 12, 30, 0, 999999)
+    type = ActiveRecord::Type::Time.new
+
+    assert_equal "'2000-01-01 12:30:00.999999'", @conn.quote(type.serialize(value))
+  end
 end