gnu: Add elixir-credo.

* gnu/packages/elixir-xyz.scm (elixir-credo): New variable.

Change-Id: I6df0d926e0fb96caa65d081892026b3495431c83
Signed-off-by: Liliana Marie Prikler <liliana.prikler@gmail.com>

gnu/packages/elixir-xyz.scm

@@ -204,6 +204,30 @@ JSON API.")
     (home-page "https://hexdocs.pm/excoveralls/")
     (license license:expat)))
 
+(define-public elixir-credo
+  (package
+    (name "elixir-credo")
+    (version "1.7.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (hexpm-uri name version))
+       (sha256
+        (base32 "18jqi9s9r1587njzdxycvmmbma30cay9iamni4f3ih54jmh1r1z9"))))
+    (build-system mix-build-system)
+    (arguments (list #:tests? #f)) ; no tests
+    (propagated-inputs (list elixir-bunt elixir-file-system elixir-jason))
+    (native-inputs (list elixir-excoveralls elixir-inch-ex))
+    (synopsis "Static code analysis tool")
+    (description
+     "Credo is a static code analysis tool for the Elixir language with a focus on
+teaching and code consistency. Credo can show you refactoring opportunities in
+your code, complex code fragments, warn you about common mistakes, show
+inconsistencies in your naming scheme and - if needed - help you enforce a
+desired coding style.")
+    (home-page "https://hexdocs.pm/credo/")
+    (license license:expat)))
+
 ;;;
 ;;; Avoid adding new packages to the end of this file. To reduce the chances
 ;;; of a merge conflict, place them above by existing packages with similar