Add Check Specific Attributes On ActiveRecord Array as a rails til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_854 TILs and counting..._
+_855 TILs and counting..._
 
 ---
 
@@ -500,6 +500,7 @@ _854 TILs and counting..._
 - [Capybara Page Status Code](rails/capybara-page-status-code.md)
 - [Cast Common Boolean-Like Values To Booleans](rails/cast-common-boolean-like-values-to-booleans.md)
 - [Change The Nullability Of A Column](rails/change-the-nullability-of-a-column.md)
+- [Check Specific Attributes On ActiveRecord Array](rails/check-specific-attributes-on-activerecord-array.md)
 - [Code Statistics For An Application](rails/code-statistics-for-an-application.md)
 - [Conditional Class Selectors in Haml](rails/conditional-class-selectors-in-haml.md)
 - [Convert A Symbol To A Constant](rails/convert-a-symbol-to-a-constant.md)

rails/check-specific-attributes-on-activerecord-array.md

@@ -0,0 +1,31 @@
+# Check Specific Attributes On ActiveRecord Array
+
+If you're writing a test against a method that returns a collection of
+ActiveRecord results, it can be tedious to check specific values for each.
+There are certainly an endless number of ways to approach those assertions.
+
+You can keep your assertion fairly concise by using nested RSpec matchers.
+There are two in particular that can help with this kind of check:
+
+```ruby
+books = get_books_by("David Sedaris")
+
+expect(books).to match_array(
+  [
+    have_attributes(
+      "title" => "Calypso",
+      "publication_year" => "2018",
+    ),
+    have_attributes(
+      "title" => "Theft By Finding",
+      "publication_year" => "2017",
+    ),
+  ],
+)
+```
+
+The outer part of the assertion is `match_array` which checks that the result
+is an array of a certain size with specific elements. On its own we'd have to
+spell out all the attributes of each book, including things like `created_at`
+and `updated_at`. However, by combining it with `have_attributes` matchers, we
+are able to make the assertion over a subset of each record's attributes.