diff --git a/spec/shakapacker/dev_server_runner_spec.rb b/spec/shakapacker/dev_server_runner_spec.rb
index 935b44f2..22aa0e71 100644
--- a/spec/shakapacker/dev_server_runner_spec.rb
+++ b/spec/shakapacker/dev_server_runner_spec.rb
@@ -1,12 +1,6 @@
 require_relative "spec_helper_initializer"
 require "shakapacker/dev_server_runner"
 
-def within_temp_directory(tmpdir = nil, &block)
-  Dir.mktmpdir("shakapacker-", tmpdir) do |dir|
-    Dir.chdir(dir, &block)
-  end
-end
-
 describe "DevServerRunner" do
   around do |example|
     within_temp_directory do
diff --git a/spec/shakapacker/manager_checker_spec.rb b/spec/shakapacker/manager_checker_spec.rb
index 604194bd..2671f5ba 100644
--- a/spec/shakapacker/manager_checker_spec.rb
+++ b/spec/shakapacker/manager_checker_spec.rb
@@ -11,12 +11,6 @@ def exitstatus
   end
 end
 
-def within_temp_directory(tmpdir = nil, &block)
-  Dir.mktmpdir("shakapacker-", tmpdir) do |dir|
-    Dir.chdir(dir, &block)
-  end
-end
-
 describe "ManagerChecker" do
   around do |example|
     within_temp_directory { example.run }
diff --git a/spec/shakapacker/webpack_runner_spec.rb b/spec/shakapacker/webpack_runner_spec.rb
index 7505035b..e9086bef 100644
--- a/spec/shakapacker/webpack_runner_spec.rb
+++ b/spec/shakapacker/webpack_runner_spec.rb
@@ -1,12 +1,6 @@
 require_relative "spec_helper_initializer"
 require "shakapacker/webpack_runner"
 
-def within_temp_directory(tmpdir = nil, &block)
-  Dir.mktmpdir("shakapacker-", tmpdir) do |dir|
-    Dir.chdir(dir, &block)
-  end
-end
-
 describe "WebpackRunner" do
   around do |example|
     within_temp_directory do
diff --git a/spec/support/package_json_helpers.rb b/spec/support/package_json_helpers.rb
index 8a7b190b..35ca3a60 100644
--- a/spec/support/package_json_helpers.rb
+++ b/spec/support/package_json_helpers.rb
@@ -11,3 +11,9 @@ def with_package_json_fallback_manager(fallback_manager)
     ENV["PACKAGE_JSON_FALLBACK_MANAGER"] = old_package_json_fallback_manager_value
   end
 end
+
+def within_temp_directory(tmpdir = nil, &block)
+  Dir.mktmpdir("shakapacker-", tmpdir) do |dir|
+    Dir.chdir(dir, &block)
+  end
+end