brew-cask-completion: import from homebrew/completions.

Formula/brew-cask-completion.rb

@@ -0,0 +1,19 @@
+class BrewCaskCompletion < Formula
+  desc "Bash & Fish completion for brew-cask"
+  homepage "https://github.com/xyb/homebrew-cask-completion"
+  url "https://github.com/xyb/homebrew-cask-completion/archive/v2.1.tar.gz"
+  sha256 "27c7ea3b7f7c060f5b5676a419220c4ce6ebf384237e859a61c346f61c8f7a1b"
+  head "https://github.com/xyb/homebrew-cask-completion.git"
+
+  bottle :unneeded
+
+  def install
+    bash_completion.install "homebrew-cask-completion.bash" => "brew-cask"
+    fish_completion.install "brew-cask.fish"
+  end
+
+  test do
+    assert_match "-F _brew_cask",
+      shell_output("source #{bash_completion}/brew-cask && complete -p brew-cask")
+  end
+end