Implements #join, #keep_if (#243)

* Implements #join, closes #182

* Implements #keep_if, closes #183

* Rubocop

Author: hslzr

lib/literal/array.rb

@@ -295,6 +295,20 @@ def intersection(*values)
 		__with__(@__value__.intersection(*values))
 	end
 
+	def	join(...)
+		@__value__.join(...)
+	end
+
+	def keep_if(...)
+		return_value = @__value__.keep_if(...)
+		case return_value
+		when Array
+			self
+		else
+			return_value
+		end
+	end
+
 	def last(...)
 		@__value__.last(...)
 	end

test/array.test.rb

@@ -354,6 +354,25 @@
 	expect(intersection.to_a) == [2]
 end
 
+test "#join joins the elements into a string" do
+	array = Literal::Array(Integer).new(1, 2, 3)
+
+	expect(array.join(", ")) == "1, 2, 3"
+	expect(array.join) == "123"
+end
+
+test "#keep_if keeps elements that match the block" do
+	array = Literal::Array(Integer).new(1, 2, 3)
+
+	expect((array.keep_if { |i| i > 1 }).to_a) == [2, 3]
+end
+
+test "#keep_if returns an enumerator if no block is given" do
+	array = Literal::Array(Integer).new(1, 2, 3)
+
+	expect(array.keep_if.class.name) == "Enumerator"
+end
+
 test "#replace replaces with passed in array" do
 	array = Literal::Array(Integer).new(1, 2, 3)