Convert Gpg test to spec.

Library/Homebrew/test/gpg_spec.rb

@@ -0,0 +1,21 @@
+require "gpg"
+
+describe Gpg do
+  subject { described_class }
+
+  describe "::create_test_key" do
+    it "creates a test key in the home directory" do
+      skip "GPG Unavailable" unless subject.available?
+
+      Dir.mktmpdir do |dir|
+        ENV["HOME"] = dir
+        dir = Pathname.new(dir)
+
+        shutup do
+          subject.create_test_key(dir)
+        end
+        expect(dir/".gnupg/secring.gpg").to exist
+      end
+    end
+  end
+end

Library/Homebrew/test/gpg_test.rb

@@ -1,18 +0,0 @@
-require "testing_env"
-require "gpg"
-
-class GpgTest < Homebrew::TestCase
-  def setup
-    super
-    skip "GPG Unavailable" unless Gpg.available?
-    @dir = Pathname.new(mktmpdir)
-  end
-
-  def test_create_test_key
-    Dir.chdir(@dir) do
-      ENV["HOME"] = @dir
-      shutup { Gpg.create_test_key(@dir) }
-      assert_predicate @dir/".gnupg/secring.gpg", :exist?
-    end
-  end
-end