Add test for Enumerator::Chain

mrbgems/mruby-enum-chain/test/enum_chain.rb

+##
+# Enumerator::Chain test
+
+assert("Enumerable#chain") do
+  a = []
+  b = {}
+  c = Object.new # not has #each method
+
+  assert_kind_of Enumerator::Chain, a.chain
+  assert_kind_of Enumerator::Chain, a.chain(b)
+  assert_kind_of Enumerator::Chain, a.chain(b, c)
+  assert_raise(NoMethodError) { c.chain }
+end
+
+assert("Enumerable#+") do
+  a = [].each
+  b = {}.reverse_each
+  c = Object.new # not has #each method
+
+  assert_kind_of Enumerator::Chain, a + b
+  assert_kind_of Enumerator::Chain, a + c
+  assert_kind_of Enumerator::Chain, b + a
+  assert_kind_of Enumerator::Chain, b + c
+  assert_raise(NoMethodError) { c + a }
+end
+
+assert("Enumerator.new") do
+  a = []
+  b = {}
+  c = Object.new # not has #each method
+
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(a, a)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(a, b)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(a, c)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(b, a)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(b, b)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(b, c)
+  assert_kind_of Enumerator::Chain, Enumerator::Chain.new(c, a)
+end
+
+assert("Enumerator::Chain#each") do
+  a = [1, 2, 3]
+
+  aa = a.chain(a)
+  assert_kind_of Enumerator, aa.each
+  assert_equal [1, 2, 3, 1, 2, 3], aa.each.to_a
+
+  aa = a.chain(a.reverse_each)
+  assert_kind_of Enumerator, aa.each
+  assert_equal [1, 2, 3, 3, 2, 1], aa.each.to_a
+
+  aa = a.chain(a.reverse_each, a)
+  assert_kind_of Enumerator, aa.each
+  assert_equal [1, 2, 3, 3, 2, 1, 1, 2, 3], aa.each.to_a
+
+  aa = a.chain(Object.new)
+  assert_kind_of Enumerator, aa.each
+  assert_raise(NoMethodError) {  aa.each.to_a }
+end
+
+assert("Enumerator::Chain#size") do
+  a = [1, 2, 3]
+
+  aa = a.chain(a)
+  assert_equal 6, aa.size
+
+  aa = a.chain(a.reverse_each)
+  assert_nil aa.size
+
+  aa = a.chain(a.reverse_each, a)
+  assert_nil aa.size
+
+  aa = a.chain(Object.new)
+  assert_nil aa.size
+end