Refactor and ease the usage of temporary env variables in test

Author: ahangarha

spec/shakapacker/compiler_spec.rb

@@ -50,10 +50,14 @@
     expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_ASSET_HOST"]).to be nil
     expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_RELATIVE_URL_ROOT"]).to be nil
 
-    ENV["SHAKAPACKER_ASSET_HOST"] = "foo.bar"
-    ENV["SHAKAPACKER_RELATIVE_URL_ROOT"] = "/baz"
-
-    expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_ASSET_HOST"]).to eq "foo.bar"
-    expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_RELATIVE_URL_ROOT"]).to eq "/baz"
+    custom_env_variables = {
+      "WEBPACKER_ASSET_HOST" => "foo.bar",
+      "WEBPACKER_RELATIVE_URL_ROOT" => "/baz"
+    }
+
+    with_env_variable(custom_env_variables) do
+      expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_ASSET_HOST"]).to eq "foo.bar"
+      expect(Shakapacker.compiler.send(:webpack_env)["SHAKAPACKER_RELATIVE_URL_ROOT"]).to eq "/baz"
+    end
   end
 end

spec/shakapacker/configuration_spec.rb

@@ -341,24 +341,17 @@
     end
 
     it "returns the value of SHAKAPACKER_ASSET_HOST if set" do
-      original_env_value = ENV["SHAKAPACKER_ASSET_HOST"]
-      ENV["SHAKAPACKER_ASSET_HOST"] = "custom_host.abc"
-
-      expect(config.asset_host).to eq "custom_host.abc"
-
-    ensure
-      ENV["SHAKAPACKER_ASSET_HOST"] = original_env_value
+      with_env_variable("SHAKAPACKER_ASSET_HOST" => "custom_host.abc") do
+        expect(config.asset_host).to eq "custom_host.abc"
+      end
     end
 
     it "returns ActionController::Base.helpers.compute_asset_host if SHAKAPACKER_ASSET_HOST is not set" do
-      original_env_value = ENV["SHAKAPACKER_ASSET_HOST"]
-      ENV["SHAKAPACKER_ASSET_HOST"] = nil
-
       allow(ActionController::Base.helpers).to receive(:compute_asset_host).and_return("domain.abc")
 
-      expect(config.asset_host).to eq "domain.abc"
-    ensure
-      ENV["SHAKAPACKER_ASSET_HOST"] = original_env_value
+      with_env_variable("SHAKAPACKER_ASSET_HOST" => nil) do
+        expect(config.asset_host).to eq "domain.abc"
+      end
     end
   end
 
@@ -372,25 +365,17 @@
     end
 
     it "returns the value of SHAKAPACKER_RELATIVE_URL_ROOT if set" do
-      original_env_value = ENV["SHAKAPACKER_RELATIVE_URL_ROOT"]
-      ENV["SHAKAPACKER_RELATIVE_URL_ROOT"] = "custom_value"
-
-      expect(config.relative_url_root).to eq "custom_value"
-
-    ensure
-      ENV["SHAKAPACKER_RELATIVE_URL_ROOT"] = original_env_value
+      with_env_variable("SHAKAPACKER_RELATIVE_URL_ROOT" => "custom_value") do
+        expect(config.relative_url_root).to eq "custom_value"
+      end
     end
 
     it "returns ActionController::Base.helpers.compute_asset_host if SHAKAPACKER_RELATIVE_URL_ROOT is not set" do
-      original_env_value = ENV["SHAKAPACKER_RELATIVE_URL_ROOT"]
-      ENV["SHAKAPACKER_RELATIVE_URL_ROOT"] = nil
-
       allow(ActionController::Base).to receive(:relative_url_root).and_return("abcd")
 
-      expect(config.relative_url_root).to eq "abcd"
-
-    ensure
-      ENV["SHAKAPACKER_RELATIVE_URL_ROOT"] = original_env_value
+      with_env_variable("SHAKAPACKER_RELATIVE_URL_ROOT" => nil) do
+        expect(config.relative_url_root).to eq "abcd"
+      end
     end
   end
 end

spec/shakapacker/spec_helper_initializer.rb

@@ -22,3 +22,21 @@ def with_rails_env(env)
   Rails.env = ActiveSupport::StringInquirer.new(original)
   reloaded_config
 end
+
+# Temportarily set env variables to a custom value
+# arg: a hash with key:value for each custom env
+#      Keys could be string or symbol
+def with_env_variable(custom_env_hash)
+  original_env = {}
+  custom_env_hash.each do |key, new_value|
+    upcased_key = key.to_s.upcase
+    original_env[upcased_key] = new_value
+    ENV[upcased_key] = new_value
+  end
+
+  yield
+ensure
+  original_env.each do |key, original_value|
+    ENV[key] = original_value
+  end
+end