Fix #microseconds conversion and #fast_string_to_time

* Use direct integer parsing in #fast_string_to_time to avoid convoluted
   conversions and errors due to truncation.
 * Use Float#round in #microseconds to avoid truncation errors.

Signed-off-by: Michael Koziarski <michael@koziarski.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/activerecord/test/cases/schema_definitions_test.rb b/activerecord/test/cases/schema_definitions_test.rb
new file mode 100644
index 0000000000..d90a95cf58
--- /dev/null
+++ b/activerecord/test/cases/schema_definitions_test.rb
@@ -0,0 +1,43 @@
+require "cases/helper"
+
+class SchemaDefinitionsTest < ActiveRecord::TestCase
+
+  REGRESSION_SAMPLES = %w{000249 125014 003912 256051 524287}
+
+  test 'fast_string_to_time converts properly' do
+    converted = ActiveRecord::ConnectionAdapters::Column.send('fast_string_to_time', "2010-01-12 12:34:56.000249")
+    assert_equal Time.mktime(2010, 01, 12, 12, 34, 56, 249), converted
+  end
+
+  test 'fallback_string_to_time converts properly' do
+    converted = ActiveRecord::ConnectionAdapters::Column.send('fallback_string_to_time', "2010-01-12 12:34:56.000249")
+    assert_equal Time.mktime(2010, 01, 12, 12, 34, 56, 249), converted
+  end
+
+  test 'fallback_string_to_time converts properly with no microseconds' do
+    converted = ActiveRecord::ConnectionAdapters::Column.send('fallback_string_to_time', "2010-01-12 12:34:56")
+    assert_equal Time.mktime(2010, 01, 12, 12, 34, 56, 0), converted
+  end
+
+  test "fast_string_to_time can handle problematic microseconds" do
+    REGRESSION_SAMPLES.each do |u|
+      converted = ActiveRecord::ConnectionAdapters::Column.send('fast_string_to_time', "2010-01-12 12:34:56.#{u}")
+      assert_equal u.to_i, converted.usec
+    end
+  end
+
+  test "microseconds can handle problematic microseconds" do
+    REGRESSION_SAMPLES.each do |u|
+      i = u.to_i
+      converted = ActiveRecord::ConnectionAdapters::Column.send('microseconds', {:sec_fraction => Rational(i, 1_000_000)})
+      assert_equal i, converted
+
+      converted = ActiveRecord::ConnectionAdapters::Column.send('microseconds', {:sec_fraction => Rational(i, 1_000_000)})
+      assert_equal i, converted
+    end
+  end
+
+  test 'fast constant is equally restrictive' do
+    assert_match ActiveRecord::ConnectionAdapters::Column::Format::NEW_ISO_DATETIME, "2010-01-12 12:34:56.555493"
+  end
+end