2 files changed, 18 insertions, 0 deletions
diff --git a/spec/ruby/library/datetime/add_spec.rb b/spec/ruby/library/datetime/add_spec.rb
new file mode 100644
index 0000000000..a6d98914bd
--- /dev/null
+++ b/spec/ruby/library/datetime/add_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require 'date'
+
+describe "DateTime#+" do
+  it "is able to add sub-millisecond precision values" do
+    datetime = DateTime.new(2017)
+    (datetime + 0.00001).to_time.usec.should == 864000
+  end
+end
diff --git a/spec/ruby/library/datetime/subtract_spec.rb b/spec/ruby/library/datetime/subtract_spec.rb
new file mode 100644
index 0000000000..ed88533246
--- /dev/null
+++ b/spec/ruby/library/datetime/subtract_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require 'date'
+
+describe "DateTime#-" do
+  it "is able to subtract sub-millisecond precision values" do
+    date = DateTime.new(2017)
+    ((date + 0.00001) - date).should == Rational(1, 100000)
+  end
+end