Add Check Specific Attributes On ActiveRecord Array as a rails til

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

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+# 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.