Impl rake build_envs

Author: sue445

_gem/lib/go_gem/rake_task.rb

@@ -86,6 +86,7 @@ def initialize(gem_name)
         define_go_test_task
         define_go_testrace_task
         define_go_fmt_task
+        define_go_build_envs_task
       end
     end
 
@@ -168,5 +169,19 @@ def define_go_fmt_task
         end
       end
     end
+
+    def define_go_build_envs_task
+      desc "Print build envs for `go build`"
+      task(:build_envs, [:env_name]) do |_, args|
+        if args[:env_name]
+          value = RakeTask.build_env_vars[args[:env_name]]
+          puts "#{args[:env_name]}=#{value}"
+        else
+          RakeTask.build_env_vars.each do |name, value|
+            puts "#{name}=#{value}"
+          end
+        end
+      end
+    end
   end
 end

_gem/sig/go_gem/rake_task.rbs

@@ -38,6 +38,8 @@ module GoGem
 
     def define_go_fmt_task: () -> void
 
+    def define_go_build_envs_task: () -> void
+
     def within_target_dir: () { () -> void } -> void
 
     def ext_dir: () -> String

_gem/spec/go_gem/rake_task_spec.rb

@@ -17,6 +17,7 @@
       it { should be_task_defined("go:test") }
       it { should be_task_defined("go:testrace") }
       it { should be_task_defined("go:fmt") }
+      it { should be_task_defined("go:build_envs") }
 
       describe "Add additional tasks" do
         include Rake::DSL