create configuration from options only once in the boot process (#5487)

Merge pull request 5487

lib/jekyll/command.rb

@@ -37,6 +37,7 @@ module Jekyll
       #
       # Returns a full Jekyll configuration
       def configuration_from_options(options)
+        return options if options.is_a?(Jekyll::Configuration)
         Jekyll.configuration(options)
       end
 

lib/jekyll/commands/serve.rb

@@ -32,11 +32,12 @@ module Jekyll
             cmd.action do |_, opts|
               opts["serving"] = true
               opts["watch"  ] = true unless opts.key?("watch")
-              config = opts["config"]
-              opts["url"] = default_url(opts) if Jekyll.env == "development"
-              Build.process(opts)
-              opts["config"] = config
-              Serve.process(opts)
+
+              config = configuration_from_options(opts)
+              if Jekyll.env == "development"
+                config["url"] = default_url(config)
+              end
+              [Build, Serve].each { |klass| klass.process(config) }
             end
           end
         end

test/test_commands_serve.rb

@@ -82,16 +82,26 @@ class TestCommandsServe < JekyllUnitTest
       end
 
       should "keep config between build and serve" do
-        custom_options = {
+        options = {
           "config"  => %w(_config.yml _development.yml),
           "serving" => true,
           "watch"   => false, # for not having guard output when running the tests
           "url"     => "http://localhost:4000",
         }
+        config = Jekyll::Configuration.from(options)
 
-        expect(Jekyll::Commands::Serve).to receive(:process).with(custom_options)
-        @merc.execute(:serve, { "config" => %w(_config.yml _development.yml),
-                                "watch"  => false, })
+        allow(Jekyll::Command).to(
+          receive(:configuration_from_options).with(options).and_return(config)
+        )
+        allow(Jekyll::Command).to(
+          receive(:configuration_from_options).with(config).and_return(config)
+        )
+
+        expect(Jekyll::Commands::Build).to(
+          receive(:process).with(config).and_call_original
+        )
+        expect(Jekyll::Commands::Serve).to receive(:process).with(config)
+        @merc.execute(:serve, options)
       end
 
       context "in development environment" do
@@ -175,5 +185,12 @@ class TestCommandsServe < JekyllUnitTest
         end
       end
     end
+
+    should "read `configuration` only once" do
+      allow(Jekyll::Commands::Serve).to receive(:start_up_webrick)
+
+      expect(Jekyll).to receive(:configuration).once.and_call_original
+      @merc.execute(:serve, { "watch" => false })
+    end
   end
 end