Add ceildiv spec

core/integer/ceildiv_spec.rb

@@ -0,0 +1,22 @@
+require_relative '../../spec_helper'
+
+describe "Integer#ceildiv" do
+  ruby_version_is '3.2' do
+    it "returns a quotient of division which is rounded up to the nearest integer" do
+      0.ceildiv(3).should eql(0)
+      1.ceildiv(3).should eql(1)
+      3.ceildiv(3).should eql(1)
+      4.ceildiv(3).should eql(2)
+
+      4.ceildiv(-3).should eql(-1)
+      -4.ceildiv(3).should eql(-1)
+      -4.ceildiv(-3).should eql(2)
+
+      3.ceildiv(1.2).should eql(3)
+      3.ceildiv(6/5r).should eql(3)
+
+      (10**100-11).ceildiv(10**99-1).should eql(10)
+      (10**100-9).ceildiv(10**99-1).should eql(11)
+    end
+  end
+end