diff --git a/mrbgems/mruby-range-ext/test/range.rb b/mrbgems/mruby-range-ext/test/range.rb
index 4ae575669..d37712926 100644
--- a/mrbgems/mruby-range-ext/test/range.rb
+++ b/mrbgems/mruby-range-ext/test/range.rb
@@ -178,3 +178,37 @@ assert('Range#min given a block') do
   assert_equal nil, ((100..10).min { |x, y| x <=> y })
   assert_equal nil, ((5...5).min { |x, y| x <=> y })
 end
+
+assert('Range#overlap?') do
+  assert_false((0..2).overlap?(-2..-1))
+  assert_false((0..2).overlap?(-2...0))
+  assert_true((0..2).overlap?(-1..0))
+  assert_true((0..2).overlap?(1..2))
+  assert_true((0..2).overlap?(2..3))
+  assert_false((0..2).overlap?(3...4))
+  assert_false((0...2).overlap?(2..3))
+
+  assert_true((..0).overlap?(-1..0))
+  assert_true((...0).overlap?(-1..0))
+  assert_true((..0).overlap?(0..1))
+  assert_true((..0).overlap?(..1))
+  assert_false((..0).overlap?(1..2))
+  assert_false((...0).overlap?(0..1))
+
+  assert_false((0..).overlap?(-2..-1))
+  assert_false((0..).overlap?(...0))
+  assert_true((0..).overlap?(..0))
+  assert_true((0..).overlap?(0..1))
+  assert_true((0..).overlap?(1..2))
+  assert_true((0..).overlap?(-1..0))
+  assert_true((0..).overlap?(1..))
+
+  assert_true((0..).overlap?(-1..0))
+  assert_true((0..).overlap?(..0))
+  assert_true((0..).overlap?(0..1))
+  assert_true((0..).overlap?(1..2))
+  assert_true((0..).overlap?(1..))
+
+  assert_raise(TypeError) { (0..).overlap?(1) }
+  assert_raise(TypeError) { (0..).overlap?(nil) }
+end