1 files changed, 16 insertions, 0 deletions
diff --git a/Library/Homebrew/cask/spec/support/env_helper.rb b/Library/Homebrew/cask/spec/support/env_helper.rb
new file mode 100644
index 000000000..0a302ef45
--- /dev/null
+++ b/Library/Homebrew/cask/spec/support/env_helper.rb
@@ -0,0 +1,16 @@
+module EnvHelper
+  class << self
+    def with_env_var(key, val)
+      was_defined = ENV.key? "key"
+      old_value = ENV["key"]
+      ENV[key] = val
+      yield
+    ensure
+      if was_defined
+        ENV[key] = old_value
+      else
+        ENV.delete(key)
+      end
+    end
+  end
+end