Add Use Tap For Better Test Data Setup as a ruby 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/).
 
-_837 TILs and counting..._
+_838 TILs and counting..._
 
 ---
 
@@ -694,6 +694,7 @@ _837 TILs and counting..._
 - [Up And Down With Integers](ruby/up-and-down-with-integers.md)
 - [Use A Case Statement As A Cond Statement](ruby/use-a-case-statement-as-a-cond-statement.md)
 - [Use dotenv In A Non-Rails Project](ruby/use-dotenv-in-a-non-rails-project.md)
+- [Use Tap For Better Test Data Setup](ruby/use-tap-for-better-test-data-setup.md)
 - [Using BCrypt To Create And Check Hashed Passwords](ruby/using-bcrypt-to-create-and-check-hashed-passwords.md)
 - [What To Do When You Don't Rescue](ruby/what-to-do-when-you-dont-rescue.md)
 - [Who Are My Ancestors?](ruby/who-are-my-ancestors.md)

ruby/use-tap-for-better-test-data-setup.md

@@ -0,0 +1,35 @@
+# Use Tap For Better Test Data Setup
+
+I often use RSpec's `let` statement to set up some test data.
+
+```ruby
+let(:order) { create(:order, name: "My Order") }
+```
+
+Often times, realistic test data requires setting up peripheral data as well.
+
+```ruby
+let(:order) do
+  order = create(:order, name: "My Order")
+  create(:item, name: "Burger", order: order, price: 4.99)
+  create(:item, name: "Fries", order: order, price: 2.99)
+  order
+end
+```
+
+This can get hard to read as the subject of the `let` gets obscured. It is also
+clumsy that we have to end with returning the `order`. This can be cleaned up
+with the use of [`#tap`](https://devdocs.io/ruby~2.5/object#method-i-tap).
+
+```ruby
+let(:order) do
+  create(:order, name: "My Order").tap do |order|
+    create(:item, name: "Burger", order: order, price: 4.99)
+    create(:item, name: "Fries", order: order, price: 2.99)
+  end
+end
+```
+
+The block notation and indentation make it clear that the `order` is what is
+getting created. Meanwhile, the interior of the block gives us a designated
+area to do what we need to with the newly-created `order` instance.