Add Comparing Arrays In RSpec as a ruby til.

README.md

@@ -170,6 +170,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Assoc For Hashes](ruby/assoc-for-hashes.md)
 - [Colorful Output With MiniTest](ruby/colorful-output-with-minitest.md)
 - [Comparing Class Hierarchy Relationships](ruby/comparing-class-hierarchy-relationships.md)
+- [Comparing Arrays In RSpec](ruby/comparing-arrays-in-rspec.md)
 - [Construct A Constant From A String](ruby/construct-a-constant-from-a-string.md)
 - [Create an Array of Stringed Numbers](ruby/create-an-array-of-stringed-numbers.md)
 - [Destructuring Arrays In Blocks](ruby/destructuring-arrays-in-blocks.md)

ruby/comparing-arrays-in-rspec.md

@@ -0,0 +1,13 @@
+# Comparing Arrays In RSpec
+
+Among its many built-in matchers, RSpec includes a set of array matchers.
+One of the array matchers is `match_array` which compares two arrays
+independent of ordering. This is handy if you need to check that a resulting
+array matches your expectations when ordering is unimportant and not
+necessarily deterministic. It can be used like so:
+
+```ruby
+expect([1,2,3]).to match_array([3,2,1])
+```
+
+This expectation is met, the test will pass.