Add a section on test naming

Closes bbatsov#131.

Author: lvh

README.md

@@ -51,6 +51,7 @@ Translations of the guide are available in the following languages:
  * [Comment Annotations](#comment-annotations)
 * [Existential](#existential)
 * [Tooling](#tooling)
+* [Testing](#Testing)
 
 ## Source Code Layout & Organization
 
@@ -1639,6 +1640,36 @@ in your endeavor to write idiomatic Clojure code.
  search for patterns of code for which there might exist a more idiomatic
  function or macro.
 
+## Testing
+
+ * <a name="test-directory-structure"></a>
+ Store your tests in a separate directory, typically `test/yourproject/` (as
+ opposed to `src/yourproject/`). Your build tool is responsible for making
+ them available in the contexts where they are necessary; most templates
+ will do this for you automatically.
+ <sup>[[link](#test-directory-structure)]</sup>
+
+ * <a name="test-ns-naming"></a>
+ Name your ns `yourproject.something-test`, a file which usually lives in
+ `test/yourproject/something_test.clj` (or `.cljc`, `cljs`).
+ <sup>[[link](#test-ns-naming)]</sup>
+
+ * <a name="test-naming"></a> When using `clojure.test`, define your tests
+ with `deftest` and name them `something-test`. For example:
+
+ ```clojure
+ ;; good
+ (deftest something-test ...)
+
+ ;; bad
+ (deftest something-tests ...)
+ (deftest test-something ...)
+ (deftest something ...)
+ ```
+
+ <sup>[[link](#test-naming)]</sup>
+
+
 # Contributing
 
 Nothing written in this guide is set in stone. It's my desire to work