Merge pull request #504 from bkeepers/autorestore-stubbed

Fix: "can't modify frozen Hash" when stubbing ENV

Author: bkeepers

lib/dotenv/diff.rb

@@ -50,7 +50,10 @@ def any?
     private
 
     def snapshot
-      ENV.to_h.freeze
+      # `dup` should not be required here, but some people use `stub_const` to replace ENV with
+      # a `Hash`. This ensures that we get a frozen copy of that instead of freezing the original.
+      # https://github.com/bkeepers/dotenv/issues/482
+      ENV.to_h.dup.freeze
     end
   end
 end

spec/dotenv_spec.rb

@@ -336,6 +336,15 @@
       Dotenv.instance_variable_set(:@diff, nil)
       expect { Dotenv.restore }.not_to raise_error
     end
+
+    it "can save and restore stubbed ENV" do
+      stub_const("ENV", ENV.to_h.merge("STUBBED" => "1"))
+      Dotenv.save
+      ENV["MODIFIED"] = "1"
+      Dotenv.restore
+      expect(ENV["STUBBED"]).to eq("1")
+      expect(ENV["MODIFED"]).to be(nil)
+    end
   end
 
   describe "modify" do