Merge pull request #30520 from rails/railties-rails-command

Run in-app rails commands via fork+load where possible

21 files changed, 339 insertions, 289 deletions

diff --git a/railties/Rakefile b/railties/Rakefile
index be7d9f96a2..74615d2358 100644
--- a/railties/Rakefile
+++ b/railties/Rakefile
@@ -45,7 +45,12 @@ namespace :test do
 
       # We could run these in parallel, but pretty much all of the
       # railties tests already run in parallel, so ¯\_(⊙︿⊙)_/¯
-      Process.waitpid fork { ARGV.clear; load file }
+      Process.waitpid fork {
+        ARGV.clear
+        Rake.application = nil
+
+        load file
+      }
 
       unless $?.success?
         failing_files << file
diff --git a/railties/test/application/asset_debugging_test.rb b/railties/test/application/asset_debugging_test.rb
index 128040262f..cb66a66175 100644
--- a/railties/test/application/asset_debugging_test.rb
+++ b/railties/test/application/asset_debugging_test.rb
@@ -44,8 +44,7 @@ module ApplicationTests
     test "assets are concatenated when debug is off and compile is off either if debug_assets param is provided" do
       # config.assets.debug and config.assets.compile are false for production environment
       ENV["RAILS_ENV"] = "production"
-      output = Dir.chdir(app_path) { `bin/rails assets:precompile --trace 2>&1` }
-      assert $?.success?, output
+      rails "assets:precompile", "--trace"
 
       # Load app env
       app "production"
diff --git a/railties/test/application/bin_setup_test.rb b/railties/test/application/bin_setup_test.rb
index a09c371033..54934dbe24 100644
--- a/railties/test/application/bin_setup_test.rb
+++ b/railties/test/application/bin_setup_test.rb
@@ -22,7 +22,7 @@ module ApplicationTests
           end
         RUBY
 
-        list_tables = lambda { `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip }
+        list_tables = lambda { rails("runner", "p ActiveRecord::Base.connection.tables").strip }
         File.write("log/test.log", "zomg!")
 
         assert_equal "[]", list_tables.call
diff --git a/railties/test/application/generators_test.rb b/railties/test/application/generators_test.rb
index 9248aec2ef..47c815d221 100644
--- a/railties/test/application/generators_test.rb
+++ b/railties/test/application/generators_test.rb
@@ -31,7 +31,7 @@ module ApplicationTests
     end
 
     test "allow running plugin new generator inside Rails app directory" do
-      FileUtils.cd(rails_root) { `ruby bin/rails plugin new vendor/plugins/bukkits` }
+      rails "plugin", "new", "vendor/plugins/bukkits"
       assert File.exist?(File.join(rails_root, "vendor/plugins/bukkits/test/dummy/config/application.rb"))
     end
 
@@ -167,7 +167,7 @@ module ApplicationTests
         config.api_only = true
       RUBY
 
-      FileUtils.cd(rails_root) { `bin/rails generate mailer notifier foo` }
+      rails "generate", "mailer", "notifier", "foo"
       assert File.exist?(File.join(rails_root, "app/views/notifier_mailer/foo.text.erb"))
       assert File.exist?(File.join(rails_root, "app/views/notifier_mailer/foo.html.erb"))
     end
@@ -190,10 +190,10 @@ module ApplicationTests
 
     test "help does not show hidden namespaces" do
       FileUtils.cd(rails_root) do
-        output = `bin/rails generate --help`
+        output = rails("generate", "--help")
         assert_no_match "active_record:migration", output
 
-        output = `bin/rails destroy --help`
+        output = rails("destroy", "--help")
         assert_no_match "active_record:migration", output
       end
     end
diff --git a/railties/test/application/help_test.rb b/railties/test/application/help_test.rb
index 3a9384b927..f728fc3b85 100644
--- a/railties/test/application/help_test.rb
+++ b/railties/test/application/help_test.rb
@@ -14,12 +14,12 @@ class HelpTest < ActiveSupport::TestCase
   end
 
   test "command works" do
-    output = Dir.chdir(app_path) { `bin/rails help` }
+    output = rails("help")
     assert_match "The most common rails commands are", output
   end
 
   test "short-cut alias works" do
-    output = Dir.chdir(app_path) { `bin/rails -h` }
+    output = rails("-h")
     assert_match "The most common rails commands are", output
   end
 end
diff --git a/railties/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index 0d02bc8a0c..d2b77bd015 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -215,20 +215,16 @@ module ApplicationTests
     end
 
     test "use schema cache dump" do
-      Dir.chdir(app_path) do
-        `rails generate model post title:string;
-         bin/rails db:migrate db:schema:cache:dump`
-      end
+      rails %w(generate model post title:string)
+      rails %w(db:migrate db:schema:cache:dump)
       require "#{app_path}/config/environment"
       ActiveRecord::Base.connection.drop_table("posts") # force drop posts table for test.
       assert ActiveRecord::Base.connection.schema_cache.data_sources("posts")
     end
 
     test "expire schema cache dump" do
-      Dir.chdir(app_path) do
-        `rails generate model post title:string;
-         bin/rails db:migrate db:schema:cache:dump db:rollback`
-      end
+      rails %w(generate model post title:string)
+      rails %w(db:migrate db:schema:cache:dump db:rollback)
       require "#{app_path}/config/environment"
       assert !ActiveRecord::Base.connection.schema_cache.data_sources("posts")
     end
diff --git a/railties/test/application/integration_test_case_test.rb b/railties/test/application/integration_test_case_test.rb
index 88b54af8c8..9edc907fce 100644
--- a/railties/test/application/integration_test_case_test.rb
+++ b/railties/test/application/integration_test_case_test.rb
@@ -15,7 +15,7 @@ module ApplicationTests
     end
 
     test "resets Action Mailer test deliveries" do
-      script("generate mailer BaseMailer welcome")
+      rails "generate", "mailer", "BaseMailer", "welcome"
 
       app_file "test/integration/mailer_integration_test.rb", <<-RUBY
         require 'test_helper'
@@ -39,8 +39,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails test 2>&1` }
-      assert_equal 0, $?.to_i, output
+      output = rails("test")
       assert_match(/0 failures, 0 errors/, output)
     end
   end
@@ -67,8 +66,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails test 2>&1` }
-      assert_equal 0, $?.to_i, output
+      output = rails("test")
       assert_match(/0 failures, 0 errors/, output)
     end
   end
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index db88eb0fd3..391676aa31 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -28,11 +28,11 @@ module ApplicationTests
 
       def db_create_and_drop(expected_database)
         Dir.chdir(app_path) do
-          output = `bin/rails db:create`
+          output = rails("db:create")
           assert_match(/Created database/, output)
           assert File.exist?(expected_database)
           assert_equal expected_database, ActiveRecord::Base.connection_config[:database]
-          output = `bin/rails db:drop`
+          output = rails("db:drop")
           assert_match(/Dropped database/, output)
           assert !File.exist?(expected_database)
         end
@@ -52,17 +52,16 @@ module ApplicationTests
       def with_database_existing
         Dir.chdir(app_path) do
           set_database_url
-          `bin/rails db:create`
+          rails "db:create"
           yield
-          `bin/rails db:drop`
+          rails "db:drop"
         end
       end
 
       test "db:create failure because database exists" do
         with_database_existing do
-          output = `bin/rails db:create 2>&1`
+          output = rails("db:create")
           assert_match(/already exists/, output)
-          assert_equal 0, $?.exitstatus
         end
       end
 
@@ -77,7 +76,7 @@ module ApplicationTests
 
       test "db:create failure because bad permissions" do
         with_bad_permissions do
-          output = `bin/rails db:create 2>&1`
+          output = rails("db:create", allow_failure: true)
           assert_match(/Couldn't create database/, output)
           assert_equal 1, $?.exitstatus
         end
@@ -85,16 +84,15 @@ module ApplicationTests
 
       test "db:drop failure because database does not exist" do
         Dir.chdir(app_path) do
-          output = `bin/rails db:drop:_unsafe --trace 2>&1`
+          output = rails("db:drop:_unsafe", "--trace")
           assert_match(/does not exist/, output)
-          assert_equal 0, $?.exitstatus
         end
       end
 
       test "db:drop failure because bad permissions" do
         with_database_existing do
           with_bad_permissions do
-            output = `bin/rails db:drop 2>&1`
+            output = rails("db:drop", allow_failure: true)
             assert_match(/Couldn't drop/, output)
             assert_equal 1, $?.exitstatus
           end
@@ -103,9 +101,9 @@ module ApplicationTests
 
       def db_migrate_and_status(expected_database)
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate`
-          output = `bin/rails db:migrate:status`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate"
+          output = rails("db:migrate:status")
           assert_match(%r{database:\s+\S*#{Regexp.escape(expected_database)}}, output)
           assert_match(/up\s+\d{14}\s+Create books/, output)
         end
@@ -124,8 +122,8 @@ module ApplicationTests
 
       def db_schema_dump
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate db:schema:dump`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate", "db:schema:dump"
           schema_dump = File.read("db/schema.rb")
           assert_match(/create_table \"books\"/, schema_dump)
         end
@@ -142,8 +140,8 @@ module ApplicationTests
 
       def db_fixtures_load(expected_database)
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate db:fixtures:load`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate", "db:fixtures:load"
           assert_match expected_database, ActiveRecord::Base.connection_config[:database]
           require "#{app_path}/app/models/book"
           assert_equal 2, Book.count
@@ -164,8 +162,8 @@ module ApplicationTests
       test "db:fixtures:load with namespaced fixture" do
         require "#{app_path}/config/environment"
         Dir.chdir(app_path) do
-          `bin/rails generate model admin::book title:string;
-           bin/rails db:migrate db:fixtures:load`
+          rails "generate", "model", "admin::book", "title:string"
+          rails "db:migrate", "db:fixtures:load"
           require "#{app_path}/app/models/admin/book"
           assert_equal 2, Admin::Book.count
         end
@@ -173,11 +171,11 @@ module ApplicationTests
 
       def db_structure_dump_and_load(expected_database)
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate db:structure:dump`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate", "db:structure:dump"
           structure_dump = File.read("db/structure.sql")
           assert_match(/CREATE TABLE (?:IF NOT EXISTS )?\"books\"/, structure_dump)
-          `bin/rails environment db:drop db:structure:load`
+          rails "environment", "db:drop", "db:structure:load"
           assert_match expected_database, ActiveRecord::Base.connection_config[:database]
           require "#{app_path}/app/models/book"
           #if structure is not loaded correctly, exception would be raised
@@ -197,20 +195,18 @@ module ApplicationTests
       end
 
       test "db:structure:dump does not dump schema information when no migrations are used" do
-        Dir.chdir(app_path) do
-          # create table without migrations
-          `bin/rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
+        # create table without migrations
+        rails "runner", "ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }"
 
-          stderr_output = capture(:stderr) { `bin/rails db:structure:dump` }
-          assert_empty stderr_output
-          structure_dump = File.read("db/structure.sql")
-          assert_match(/CREATE TABLE (?:IF NOT EXISTS )?\"posts\"/, structure_dump)
-        end
+        stderr_output = capture(:stderr) { rails("db:structure:dump", stderr: true, allow_failure: true) }
+        assert_empty stderr_output
+        structure_dump = File.read("#{app_path}/db/structure.sql")
+        assert_match(/CREATE TABLE (?:IF NOT EXISTS )?\"posts\"/, structure_dump)
       end
 
       test "db:schema:load and db:structure:load do not purge the existing database" do
         Dir.chdir(app_path) do
-          `bin/rails runner 'ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }'`
+          rails "runner", "ActiveRecord::Base.connection.create_table(:posts) {|t| t.string :title }"
 
           app_file "db/schema.rb", <<-RUBY
             ActiveRecord::Schema.define(version: 20140423102712) do
@@ -218,17 +214,17 @@ module ApplicationTests
             end
           RUBY
 
-          list_tables = lambda { `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip }
+          list_tables = lambda { rails("runner", "p ActiveRecord::Base.connection.tables").strip }
 
           assert_equal '["posts"]', list_tables[]
-          `bin/rails db:schema:load`
+          rails "db:schema:load"
           assert_equal '["posts", "comments", "schema_migrations", "ar_internal_metadata"]', list_tables[]
 
           app_file "db/structure.sql", <<-SQL
             CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255));
           SQL
 
-          `bin/rails db:structure:load`
+          rails "db:structure:load"
           assert_equal '["posts", "comments", "schema_migrations", "ar_internal_metadata", "users"]', list_tables[]
         end
       end
@@ -251,27 +247,25 @@ module ApplicationTests
             end
           RUBY
 
-          `bin/rails db:schema:load`
+          rails "db:schema:load"
 
-          tables = `bin/rails runner 'p ActiveRecord::Base.connection.tables'`.strip
+          tables = rails("runner", "p ActiveRecord::Base.connection.tables").strip
           assert_match(/"geese"/, tables)
 
-          columns = `bin/rails runner 'p ActiveRecord::Base.connection.columns("geese").map(&:name)'`.strip
+          columns = rails("runner", "p ActiveRecord::Base.connection.columns('geese').map(&:name)").strip
           assert_equal columns, '["gooseid", "name"]'
         end
       end
 
       test "db:schema:load fails if schema.rb doesn't exist yet" do
-        Dir.chdir(app_path) do
-          stderr_output = capture(:stderr) { `bin/rails db:schema:load` }
-          assert_match(/Run `rails db:migrate` to create it/, stderr_output)
-        end
+        stderr_output = capture(:stderr) { rails("db:schema:load", stderr: true, allow_failure: true) }
+        assert_match(/Run `rails db:migrate` to create it/, stderr_output)
       end
 
       def db_test_load_structure
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate db:structure:dump db:test:load_structure`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate", "db:structure:dump", "db:test:load_structure"
           ActiveRecord::Base.configurations = Rails.application.config.database_configuration
           ActiveRecord::Base.establish_connection :test
           require "#{app_path}/app/models/book"
@@ -307,7 +301,7 @@ module ApplicationTests
           RUBY
 
           Dir.chdir(app_path) do
-            database_path = `bin/rails db:setup`
+            database_path = rails("db:setup")
             assert_equal "development.sqlite3", File.basename(database_path.strip)
           end
         ensure
diff --git a/railties/test/application/rake/dev_test.rb b/railties/test/application/rake/dev_test.rb
index b25593ee1c..66e1ac9d99 100644
--- a/railties/test/application/rake/dev_test.rb
+++ b/railties/test/application/rake/dev_test.rb
@@ -17,7 +17,7 @@ module ApplicationTests
 
       test "dev:cache creates file and outputs message" do
         Dir.chdir(app_path) do
-          output = `rails dev:cache`
+          output = rails("dev:cache")
           assert File.exist?("tmp/caching-dev.txt")
           assert_match(/Development mode is now being cached/, output)
         end
@@ -25,8 +25,8 @@ module ApplicationTests
 
       test "dev:cache deletes file and outputs message" do
         Dir.chdir(app_path) do
-          `rails dev:cache` # Create caching file.
-          output = `rails dev:cache` # Delete caching file.
+          rails "dev:cache" # Create caching file.
+          output = rails("dev:cache") # Delete caching file.
           assert_not File.exist?("tmp/caching-dev.txt")
           assert_match(/Development mode is no longer being cached/, output)
         end
@@ -34,12 +34,12 @@ module ApplicationTests
 
       test "dev:cache touches tmp/restart.txt" do
         Dir.chdir(app_path) do
-          `rails dev:cache`
+          rails "dev:cache"
           assert File.exist?("tmp/restart.txt")
 
           prev_mtime = File.mtime("tmp/restart.txt")
           sleep(1)
-          `rails dev:cache`
+          rails "dev:cache"
           curr_mtime = File.mtime("tmp/restart.txt")
           assert_not_equal prev_mtime, curr_mtime
         end
diff --git a/railties/test/application/rake/log_test.rb b/railties/test/application/rake/log_test.rb
index c52be5f396..678f26db26 100644
--- a/railties/test/application/rake/log_test.rb
+++ b/railties/test/application/rake/log_test.rb
@@ -23,7 +23,7 @@ module ApplicationTests
           File.write("log/test.log", "test")
           File.write("log/dummy.log", "dummy")
 
-          `rails log:clear`
+          rails "log:clear"
 
           assert_equal 0, File.size("log/test.log")
           assert_equal 0, File.size("log/staging.log")
diff --git a/railties/test/application/rake/migrations_test.rb b/railties/test/application/rake/migrations_test.rb
index d130a58441..b0d51eb22e 100644
--- a/railties/test/application/rake/migrations_test.rb
+++ b/railties/test/application/rake/migrations_test.rb
@@ -16,21 +16,21 @@ module ApplicationTests
 
       test "running migrations with given scope" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string`
+          rails "generate", "model", "user", "username:string", "password:string"
 
           app_file "db/migrate/01_a_migration.bukkits.rb", <<-MIGRATION
             class AMigration < ActiveRecord::Migration::Current
             end
           MIGRATION
 
-          output = `bin/rails db:migrate SCOPE=bukkits`
+          output = rails("db:migrate", "SCOPE=bukkits")
           assert_no_match(/create_table\(:users\)/, output)
           assert_no_match(/CreateUsers/, output)
           assert_no_match(/add_column\(:users, :email, :string\)/, output)
 
           assert_match(/AMigration: migrated/, output)
 
-          output = `bin/rails db:migrate SCOPE=bukkits VERSION=0`
+          output = rails("db:migrate", "SCOPE=bukkits", "VERSION=0")
           assert_no_match(/drop_table\(:users\)/, output)
           assert_no_match(/CreateUsers/, output)
           assert_no_match(/remove_column\(:users, :email\)/, output)
@@ -41,38 +41,38 @@ module ApplicationTests
 
       test "migration with empty version" do
         Dir.chdir(app_path) do
-          output = `bin/rails db:migrate VERSION= 2>&1`
+          output = rails("db:migrate", "VERSION=", allow_failure: true)
           assert_match(/Empty VERSION provided/, output)
 
-          output = `bin/rails db:migrate:redo VERSION= 2>&1`
+          output = rails("db:migrate:redo", "VERSION=", allow_failure: true)
           assert_match(/Empty VERSION provided/, output)
 
-          output = `bin/rails db:migrate:up VERSION= 2>&1`
+          output = rails("db:migrate:up", "VERSION=", allow_failure: true)
           assert_match(/VERSION is required/, output)
 
-          output = `bin/rails db:migrate:up 2>&1`
+          output = rails("db:migrate:up", allow_failure: true)
           assert_match(/VERSION is required/, output)
 
-          output = `bin/rails db:migrate:down VERSION= 2>&1`
+          output = rails("db:migrate:down", "VERSION=", allow_failure: true)
           assert_match(/VERSION is required - To go down one migration, use db:rollback/, output)
 
-          output = `bin/rails db:migrate:down 2>&1`
+          output = rails("db:migrate:down", allow_failure: true)
           assert_match(/VERSION is required - To go down one migration, use db:rollback/, output)
         end
       end
 
       test "model and migration generator with change syntax" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
 
-          output = `bin/rails db:migrate`
+          output = rails("db:migrate")
           assert_match(/create_table\(:users\)/, output)
           assert_match(/CreateUsers: migrated/, output)
           assert_match(/add_column\(:users, :email, :string\)/, output)
           assert_match(/AddEmailToUsers: migrated/, output)
 
-          output = `bin/rails db:rollback STEP=2`
+          output = rails("db:rollback", "STEP=2")
           assert_match(/drop_table\(:users\)/, output)
           assert_match(/CreateUsers: reverted/, output)
           assert_match(/remove_column\(:users, :email, :string\)/, output)
@@ -81,23 +81,23 @@ module ApplicationTests
       end
 
       test "migration status when schema migrations table is not present" do
-        output = Dir.chdir(app_path) { `bin/rails db:migrate:status 2>&1` }
+        output = rails("db:migrate:status", allow_failure: true)
         assert_equal "Schema migrations table does not exist yet.\n", output
       end
 
       test "migration status" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
 
-          `bin/rails db:rollback STEP=1`
-          output = `bin/rails db:migrate:status`
+          rails "db:rollback", "STEP=1"
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/down\s+\d{14}\s+Add email to users/, output)
@@ -108,17 +108,17 @@ module ApplicationTests
         add_to_config("config.active_record.timestamped_migrations = false")
 
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/up\s+\d{3,}\s+Add email to users/, output)
 
-          `bin/rails db:rollback STEP=1`
-          output = `bin/rails db:migrate:status`
+          rails "db:rollback", "STEP=1"
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/down\s+\d{3,}\s+Add email to users/, output)
@@ -127,23 +127,23 @@ module ApplicationTests
 
       test "migration status after rollback and redo" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
 
-          `bin/rails db:rollback STEP=2`
-          output = `bin/rails db:migrate:status`
+          rails "db:rollback", "STEP=2"
+          output = rails("db:migrate:status")
 
           assert_match(/down\s+\d{14}\s+Create users/, output)
           assert_match(/down\s+\d{14}\s+Add email to users/, output)
 
-          `bin/rails db:migrate:redo`
-          output = `bin/rails db:migrate:status`
+          rails "db:migrate:redo"
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
@@ -152,23 +152,23 @@ module ApplicationTests
 
       test "migration status after rollback and forward" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
 
-          `bin/rails db:rollback STEP=2`
-          output = `bin/rails db:migrate:status`
+          rails "db:rollback", "STEP=2"
+          output = rails("db:migrate:status")
 
           assert_match(/down\s+\d{14}\s+Create users/, output)
           assert_match(/down\s+\d{14}\s+Add email to users/, output)
 
-          `bin/rails db:forward STEP=2`
-          output = `bin/rails db:migrate:status`
+          rails "db:forward", "STEP=2"
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+Add email to users/, output)
@@ -177,30 +177,30 @@ module ApplicationTests
 
       test "raise error on any move when current migration does not exist" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate
-           rm db/migrate/*email*.rb`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
+          `rm db/migrate/*email*.rb`
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+\** NO FILE \**/, output)
 
-          output = `bin/rails db:rollback 2>&1`
+          output = rails("db:rollback", allow_failure: true)
           assert_match(/rails aborted!/, output)
           assert_match(/ActiveRecord::UnknownMigrationVersionError:/, output)
           assert_match(/No migration with version number\s\d{14}\./, output)
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+\** NO FILE \**/, output)
 
-          output = `bin/rails db:forward 2>&1`
+          output = rails("db:forward", allow_failure: true)
           assert_match(/rails aborted!/, output)
           assert_match(/ActiveRecord::UnknownMigrationVersionError:/, output)
           assert_match(/No migration with version number\s\d{14}\./, output)
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+\** NO FILE \**/, output)
         end
@@ -210,23 +210,23 @@ module ApplicationTests
         add_to_config("config.active_record.timestamped_migrations = false")
 
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/up\s+\d{3,}\s+Add email to users/, output)
 
-          `bin/rails db:rollback STEP=2`
-          output = `bin/rails db:migrate:status`
+          rails "db:rollback", "STEP=2"
+          output = rails("db:migrate:status")
 
           assert_match(/down\s+\d{3,}\s+Create users/, output)
           assert_match(/down\s+\d{3,}\s+Add email to users/, output)
 
-          `bin/rails db:migrate:redo`
-          output = `bin/rails db:migrate:status`
+          rails "db:migrate:redo"
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{3,}\s+Create users/, output)
           assert_match(/up\s+\d{3,}\s+Add email to users/, output)
@@ -246,9 +246,9 @@ module ApplicationTests
             end
           MIGRATION
 
-          `bin/rails db:migrate`
+          rails "db:migrate"
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+001\s+One migration/, output)
           assert_match(/up\s+002\s+Two migration/, output)
@@ -259,19 +259,19 @@ module ApplicationTests
         add_to_config("config.active_record.dump_schema_after_migration = false")
 
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string`
-          output = `bin/rails generate model author name:string`
+          rails "generate", "model", "book", "title:string"
+          output = rails("generate", "model", "author", "name:string")
           version = output =~ %r{[^/]+db/migrate/(\d+)_create_authors\.rb} && $1
 
-          `bin/rails db:migrate db:rollback db:forward db:migrate:up db:migrate:down VERSION=#{version}`
+          rails "db:migrate", "db:rollback", "db:forward", "db:migrate:up", "db:migrate:down", "VERSION=#{version}"
           assert !File.exist?("db/schema.rb"), "should not dump schema when configured not to"
         end
 
         add_to_config("config.active_record.dump_schema_after_migration = true")
 
         Dir.chdir(app_path) do
-          `bin/rails generate model reviews book_id:integer`
-          `bin/rails db:migrate`
+          rails "generate", "model", "reviews", "book_id:integer"
+          rails "db:migrate"
 
           structure_dump = File.read("db/schema.rb")
           assert_match(/create_table "reviews"/, structure_dump)
@@ -280,8 +280,8 @@ module ApplicationTests
 
       test "default schema generation after migration" do
         Dir.chdir(app_path) do
-          `bin/rails generate model book title:string;
-           bin/rails db:migrate`
+          rails "generate", "model", "book", "title:string"
+          rails "db:migrate"
 
           structure_dump = File.read("db/schema.rb")
           assert_match(/create_table "books"/, structure_dump)
@@ -290,12 +290,12 @@ module ApplicationTests
 
       test "migration status migrated file is deleted" do
         Dir.chdir(app_path) do
-          `bin/rails generate model user username:string password:string;
-           bin/rails generate migration add_email_to_users email:string;
-           bin/rails db:migrate
-           rm db/migrate/*email*.rb`
+          rails "generate", "model", "user", "username:string", "password:string"
+          rails "generate", "migration", "add_email_to_users", "email:string"
+          rails "db:migrate"
+          `rm db/migrate/*email*.rb`
 
-          output = `bin/rails db:migrate:status`
+          output = rails("db:migrate:status")
 
           assert_match(/up\s+\d{14}\s+Create users/, output)
           assert_match(/up\s+\d{14}\s+\** NO FILE \**/, output)
diff --git a/railties/test/application/rake/restart_test.rb b/railties/test/application/rake/restart_test.rb
index ed96dcb6b1..8614560bf2 100644
--- a/railties/test/application/rake/restart_test.rb
+++ b/railties/test/application/rake/restart_test.rb
@@ -17,12 +17,12 @@ module ApplicationTests
 
       test "rails restart touches tmp/restart.txt" do
         Dir.chdir(app_path) do
-          `bin/rails restart`
+          rails "restart"
           assert File.exist?("tmp/restart.txt")
 
           prev_mtime = File.mtime("tmp/restart.txt")
           sleep(1)
-          `bin/rails restart`
+          rails "restart"
           curr_mtime = File.mtime("tmp/restart.txt")
           assert_not_equal prev_mtime, curr_mtime
         end
@@ -31,7 +31,7 @@ module ApplicationTests
       test "rails restart should work even if tmp folder does not exist" do
         Dir.chdir(app_path) do
           FileUtils.remove_dir("tmp")
-          `bin/rails restart`
+          rails "restart"
           assert File.exist?("tmp/restart.txt")
         end
       end
diff --git a/railties/test/application/rake/tmp_test.rb b/railties/test/application/rake/tmp_test.rb
index 8641d140cb..048fd7adcc 100644
--- a/railties/test/application/rake/tmp_test.rb
+++ b/railties/test/application/rake/tmp_test.rb
@@ -26,7 +26,7 @@ module ApplicationTests
           FileUtils.mkdir_p("tmp/screenshots")
           FileUtils.touch("tmp/screenshots/fail.png")
 
-          `rails tmp:clear`
+          rails "tmp:clear"
 
           assert_not File.exist?("tmp/cache/cache_file")
           assert_not File.exist?("tmp/sockets/socket_file")
@@ -36,9 +36,7 @@ module ApplicationTests
 
       test "tmp:clear should work if folder missing" do
         FileUtils.remove_dir("#{app_path}/tmp")
-        errormsg = Dir.chdir(app_path) { `bin/rails tmp:clear` }
-        assert_predicate $?, :success?
-        assert_empty errormsg
+        rails "tmp:clear"
       end
     end
   end
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index fe59bed874..f9b14f98cb 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -1,11 +1,12 @@
 # frozen_string_literal: true
 
 require "isolation/abstract_unit"
+require "env_helpers"
 require "active_support/core_ext/string/strip"
 
 module ApplicationTests
   class RakeTest < ActiveSupport::TestCase
-    include ActiveSupport::Testing::Isolation
+    include ActiveSupport::Testing::Isolation, EnvHelpers
 
     def setup
       build_app
@@ -26,20 +27,20 @@ module ApplicationTests
     end
 
     test "task is protected when previous migration was production" do
-      Dir.chdir(app_path) do
-        output = `bin/rails generate model product name:string;
-         env RAILS_ENV=production bin/rails db:create db:migrate;
-         env RAILS_ENV=production bin/rails db:test:prepare test 2>&1`
+      with_rails_env "production" do
+        rails "generate", "model", "product", "name:string"
+        rails "db:create", "db:migrate"
+        output = rails("db:test:prepare", allow_failure: true)
 
         assert_match(/ActiveRecord::ProtectedEnvironmentError/, output)
       end
     end
 
     def test_not_protected_when_previous_migration_was_not_production
-      Dir.chdir(app_path) do
-        output = `bin/rails generate model product name:string;
-         env RAILS_ENV=test bin/rails db:create db:migrate;
-         env RAILS_ENV=test bin/rails db:test:prepare test 2>&1`
+      with_rails_env "test" do
+        rails "generate", "model", "product", "name:string"
+        rails "db:create", "db:migrate"
+        output = Dir.chdir(app_path) { rails("db:test:prepare", "test") }
 
         refute_match(/ActiveRecord::ProtectedEnvironmentError/, output)
       end
@@ -56,7 +57,7 @@ module ApplicationTests
         Rails.application.initialize!
       RUBY
 
-      assert_match("SuperMiddleware", Dir.chdir(app_path) { `bin/rails middleware` })
+      assert_match("SuperMiddleware", rails("middleware"))
     end
 
     def test_initializers_are_executed_in_rake_tasks
@@ -71,7 +72,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails do_nothing` }
+      output = rails("do_nothing")
       assert_match "Doing something...", output
     end
 
@@ -92,7 +93,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails do_nothing` }
+      output = rails("do_nothing")
       assert_match "Hello world", output
     end
 
@@ -120,7 +121,7 @@ module ApplicationTests
 
     def test_code_statistics_sanity
       assert_match "Code LOC: 25     Test LOC: 0     Code to Test Ratio: 1:0.0",
-        Dir.chdir(app_path) { `bin/rails stats` }
+        rails("stats")
     end
 
     def test_rails_routes_calls_the_route_inspector
@@ -130,7 +131,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails routes` }
+      output = rails("routes")
       assert_equal <<-MESSAGE.strip_heredoc, output
                          Prefix Verb URI Pattern                                                                       Controller#Action
                            cart GET  /cart(.:format)                                                                   cart#show
@@ -158,7 +159,7 @@ module ApplicationTests
                          "          DELETE /post(.:format)      posts#destroy",
                          "          POST   /post(.:format)      posts#create\n"].join("\n")
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c PostController` }
+      output = rails("routes", "-c", "PostController")
       assert_equal expected_output, output
     end
 
@@ -171,7 +172,7 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails routes -g show` }
+      output = rails("routes", "-g", "show", allow_failure: true)
       assert_equal <<-MESSAGE.strip_heredoc, output
                          Prefix Verb URI Pattern                                                                       Controller#Action
                            cart GET  /cart(.:format)                                                                   cart#show
@@ -180,14 +181,14 @@ module ApplicationTests
              rails_disk_service GET  /rails/active_storage/disk/:encoded_key/*filename(.:format)                       active_storage/disk#show
       MESSAGE
 
-      output = Dir.chdir(app_path) { `bin/rails routes -g POST` }
+      output = rails("routes", "-g", "POST")
       assert_equal <<-MESSAGE.strip_heredoc, output
                          Prefix Verb URI Pattern                                    Controller#Action
                                 POST /cart(.:format)                                cart#create
            rails_direct_uploads POST /rails/active_storage/direct_uploads(.:format) active_storage/direct_uploads#create
       MESSAGE
 
-      output = Dir.chdir(app_path) { `bin/rails routes -g basketballs` }
+      output = rails("routes", "-g", "basketballs")
       assert_equal "     Prefix Verb URI Pattern            Controller#Action\n" \
                    "basketballs GET  /basketballs(.:format) basketball#index\n", output
     end
@@ -200,13 +201,13 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c cart` }
+      output = rails("routes", "-c", "cart")
       assert_equal "Prefix Verb URI Pattern     Controller#Action\n  cart GET  /cart(.:format) cart#show\n", output
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c Cart` }
+      output = rails("routes", "-c", "Cart")
       assert_equal "Prefix Verb URI Pattern     Controller#Action\n  cart GET  /cart(.:format) cart#show\n", output
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c CartController` }
+      output = rails("routes", "-c", "CartController")
       assert_equal "Prefix Verb URI Pattern     Controller#Action\n  cart GET  /cart(.:format) cart#show\n", output
     end
 
@@ -227,10 +228,10 @@ module ApplicationTests
                          "                DELETE /admin/post(.:format)      admin/posts#destroy",
                          "                POST   /admin/post(.:format)      admin/posts#create\n"].join("\n")
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c Admin::PostController` }
+      output = rails("routes", "-c", "Admin::PostController")
       assert_equal expected_output, output
 
-      output = Dir.chdir(app_path) { `bin/rails routes -c PostController` }
+      output = rails("routes", "-c", "PostController")
       assert_equal expected_output, output
     end
 
@@ -240,7 +241,7 @@ module ApplicationTests
         end
       RUBY
 
-      assert_equal <<-MESSAGE.strip_heredoc, Dir.chdir(app_path) { `bin/rails routes` }
+      assert_equal <<-MESSAGE.strip_heredoc, rails("routes")
                          Prefix Verb URI Pattern                                                                       Controller#Action
              rails_service_blob GET  /rails/active_storage/blobs/:signed_id/*filename(.:format)                        active_storage/blobs#show
            rails_blob_variation GET  /rails/active_storage/variants/:signed_blob_id/:variation_key/*filename(.:format) active_storage/variants#show
@@ -279,43 +280,37 @@ module ApplicationTests
         end
       RUBY
 
-      output = Dir.chdir(app_path) { `bin/rails log_something RAILS_ENV=production && cat log/production.log` }
-      assert_match "Sample log message", output
+      rails "log_something", "RAILS_ENV=production"
+      assert_match "Sample log message", File.read("#{app_path}/log/production.log")
     end
 
     def test_loading_specific_fixtures
-      Dir.chdir(app_path) do
-        `bin/rails generate model user username:string password:string;
-         bin/rails generate model product name:string;
-         bin/rails db:migrate`
-      end
+      rails "generate", "model", "user", "username:string", "password:string"
+      rails "generate", "model", "product", "name:string"
+      rails "db:migrate"
 
       require "#{rails_root}/config/environment"
 
       # loading a specific fixture
-      errormsg = Dir.chdir(app_path) { `bin/rails db:fixtures:load FIXTURES=products` }
-      assert $?.success?, errormsg
+      rails "db:fixtures:load", "FIXTURES=products"
 
       assert_equal 2, ::AppTemplate::Application::Product.count
       assert_equal 0, ::AppTemplate::Application::User.count
     end
 
     def test_loading_only_yml_fixtures
-      Dir.chdir(app_path) do
-        `bin/rails db:migrate`
-      end
+      rails "db:migrate"
 
       app_file "test/fixtures/products.csv", ""
 
       require "#{rails_root}/config/environment"
-      errormsg = Dir.chdir(app_path) { `bin/rails db:fixtures:load` }
-      assert $?.success?, errormsg
+      rails "db:fixtures:load"
     end
 
     def test_scaffold_tests_pass_by_default
+      rails "generate", "scaffold", "user", "username:string", "password:string"
       output = Dir.chdir(app_path) do
-        `bin/rails generate scaffold user username:string password:string;
-         RAILS_ENV=test bin/rails db:migrate test`
+        `RAILS_ENV=test bin/rails db:migrate test`
       end
 
       assert_match(/7 runs, 9 assertions, 0 failures, 0 errors/, output)
@@ -332,9 +327,9 @@ module ApplicationTests
         end
       RUBY
 
+      rails "generate", "scaffold", "user", "username:string", "password:string"
       output = Dir.chdir(app_path) do
-        `bin/rails generate scaffold user username:string password:string;
-         RAILS_ENV=test bin/rails db:migrate test`
+        `RAILS_ENV=test bin/rails db:migrate test`
       end
 
       assert_match(/5 runs, 7 assertions, 0 failures, 0 errors/, output)
@@ -342,11 +337,11 @@ module ApplicationTests
     end
 
     def test_scaffold_with_references_columns_tests_pass_by_default
+      rails "generate", "model", "Product"
+      rails "generate", "model", "Cart"
+      rails "generate", "scaffold", "LineItems", "product:references", "cart:belongs_to"
       output = Dir.chdir(app_path) do
-        `bin/rails generate model Product;
-         bin/rails generate model Cart;
-         bin/rails generate scaffold LineItems product:references cart:belongs_to;
-         RAILS_ENV=test bin/rails db:migrate test`
+        `RAILS_ENV=test bin/rails db:migrate test`
       end
 
       assert_match(/7 runs, 9 assertions, 0 failures, 0 errors/, output)
@@ -355,53 +350,45 @@ module ApplicationTests
 
     def test_db_test_prepare_when_using_sql_format
       add_to_config "config.active_record.schema_format = :sql"
-      output = Dir.chdir(app_path) do
-        `bin/rails generate scaffold user username:string;
-         bin/rails db:migrate;
-         bin/rails db:test:prepare 2>&1 --trace`
+      rails "generate", "scaffold", "user", "username:string"
+      rails "db:migrate"
+      output = with_rails_env("test") do
+        rails "db:test:prepare", "--trace"
       end
       assert_match(/Execute db:test:load_structure/, output)
     end
 
     def test_rake_dump_structure_should_respect_db_structure_env_variable
-      Dir.chdir(app_path) do
-        # ensure we have a schema_migrations table to dump
-        `bin/rails db:migrate db:structure:dump SCHEMA=db/my_structure.sql`
-      end
+      # ensure we have a schema_migrations table to dump
+      rails "db:migrate", "db:structure:dump", "SCHEMA=db/my_structure.sql"
       assert File.exist?(File.join(app_path, "db", "my_structure.sql"))
     end
 
     def test_rake_dump_structure_should_be_called_twice_when_migrate_redo
       add_to_config "config.active_record.schema_format = :sql"
 
-      output = Dir.chdir(app_path) do
-        `bin/rails g model post title:string;
-         bin/rails db:migrate:redo 2>&1 --trace;`
-      end
+      rails "g", "model", "post", "title:string"
+      output = rails("db:migrate:redo", "--trace")
 
       # expect only Invoke db:structure:dump (first_time)
       assert_no_match(/^\*\* Invoke db:structure:dump\s+$/, output)
     end
 
     def test_rake_dump_schema_cache
-      Dir.chdir(app_path) do
-        `bin/rails generate model post title:string;
-         bin/rails generate model product name:string;
-         bin/rails db:migrate db:schema:cache:dump`
-      end
+      rails "generate", "model", "post", "title:string"
+      rails "generate", "model", "product", "name:string"
+      rails "db:migrate", "db:schema:cache:dump"
       assert File.exist?(File.join(app_path, "db", "schema_cache.yml"))
     end
 
     def test_rake_clear_schema_cache
-      Dir.chdir(app_path) do
-        `bin/rails db:schema:cache:dump db:schema:cache:clear`
-      end
+      rails "db:schema:cache:dump", "db:schema:cache:clear"
       assert !File.exist?(File.join(app_path, "db", "schema_cache.yml"))
     end
 
     def test_copy_templates
       Dir.chdir(app_path) do
-        `bin/rails app:templates:copy`
+        rails "app:templates:copy"
         %w(controller mailer scaffold).each do |dir|
           assert File.exist?(File.join(app_path, "lib", "templates", "erb", dir))
         end
@@ -415,10 +402,7 @@ module ApplicationTests
       app_file "config/initializers/dummy.rb", "puts 'Hello, World!'"
       app_file "template.rb", ""
 
-      output = Dir.chdir(app_path) do
-        `bin/rails app:template LOCATION=template.rb`
-      end
-
+      output = rails("app:template", "LOCATION=template.rb")
       assert_match(/Hello, World!/, output)
     end
   end
diff --git a/railties/test/application/runner_test.rb b/railties/test/application/runner_test.rb
index a66f288795..64c46c4b45 100644
--- a/railties/test/application/runner_test.rb
+++ b/railties/test/application/runner_test.rb
@@ -26,22 +26,19 @@ module ApplicationTests
     end
 
     def test_should_include_runner_in_shebang_line_in_help_without_option
-      assert_match "/rails runner", Dir.chdir(app_path) { `bin/rails runner` }
+      assert_match "/rails runner", rails("runner", allow_failure: true)
     end
 
     def test_should_include_runner_in_shebang_line_in_help
-      assert_match "/rails runner", Dir.chdir(app_path) { `bin/rails runner --help` }
+      assert_match "/rails runner", rails("runner", "--help")
     end
 
     def test_should_run_ruby_statement
-      assert_match "42", Dir.chdir(app_path) { `bin/rails runner "puts User.count"` }
+      assert_match "42", rails("runner", "puts User.count")
     end
 
     def test_should_set_argv_when_running_code
-      output = Dir.chdir(app_path) {
-        # Both long and short args, at start and end of ARGV
-        `bin/rails runner "puts ARGV.join(',')" --foo a1 -b a2 a3 --moo`
-      }
+      output = rails("runner", "puts ARGV.join(',')", "--foo", "a1", "-b", "a2", "a3", "--moo")
       assert_equal "--foo,a1,-b,a2,a3,--moo", output.chomp
     end
 
@@ -50,7 +47,7 @@ module ApplicationTests
       puts User.count
       SCRIPT
 
-      assert_match "42", Dir.chdir(app_path) { `bin/rails runner "bin/count_users.rb"` }
+      assert_match "42", rails("runner", "bin/count_users.rb")
     end
 
     def test_no_minitest_loaded_in_production_mode
@@ -67,7 +64,7 @@ module ApplicationTests
       puts $0
       SCRIPT
 
-      assert_match "bin/dollar0.rb", Dir.chdir(app_path) { `bin/rails runner "bin/dollar0.rb"` }
+      assert_match "bin/dollar0.rb", rails("runner", "bin/dollar0.rb")
     end
 
     def test_should_set_dollar_program_name_to_file
@@ -75,7 +72,7 @@ module ApplicationTests
       puts $PROGRAM_NAME
       SCRIPT
 
-      assert_match "bin/program_name.rb", Dir.chdir(app_path) { `bin/rails runner "bin/program_name.rb"` }
+      assert_match "bin/program_name.rb", rails("runner", "bin/program_name.rb")
     end
 
     def test_passes_extra_args_to_file
@@ -83,7 +80,7 @@ module ApplicationTests
       p ARGV
       SCRIPT
 
-      assert_match %w( a b ).to_s, Dir.chdir(app_path) { `bin/rails runner "bin/program_name.rb" a b` }
+      assert_match %w( a b ).to_s, rails("runner", "bin/program_name.rb", "a", "b")
     end
 
     def test_should_run_stdin
@@ -101,34 +98,34 @@ module ApplicationTests
         end
       RUBY
 
-      assert_match "true", Dir.chdir(app_path) { `bin/rails runner "puts Rails.application.config.ran"` }
+      assert_match "true", rails("runner", "puts Rails.application.config.ran")
     end
 
     def test_default_environment
-      assert_match "development", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
+      assert_match "development", rails("runner", "puts Rails.env")
     end
 
     def test_runner_detects_syntax_errors
-      output = Dir.chdir(app_path) { `bin/rails runner "puts 'hello world" 2>&1` }
+      output = rails("runner", "puts 'hello world", allow_failure: true)
       assert_not $?.success?
       assert_match "unterminated string meets end of file", output
     end
 
     def test_runner_detects_bad_script_name
-      output = Dir.chdir(app_path) { `bin/rails runner "iuiqwiourowe" 2>&1` }
+      output = rails("runner", "iuiqwiourowe", allow_failure: true)
       assert_not $?.success?
       assert_match "undefined local variable or method `iuiqwiourowe' for", output
     end
 
     def test_environment_with_rails_env
       with_rails_env "production" do
-        assert_match "production", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
+        assert_match "production", rails("runner", "puts Rails.env")
       end
     end
 
     def test_environment_with_rack_env
       with_rack_env "production" do
-        assert_match "production", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
+        assert_match "production", rails("runner", "puts Rails.env")
       end
     end
   end
diff --git a/railties/test/application/test_runner_test.rb b/railties/test/application/test_runner_test.rb
index 1eda2a5eaf..e92a0466dd 100644
--- a/railties/test/application/test_runner_test.rb
+++ b/railties/test/application/test_runner_test.rb
@@ -59,7 +59,7 @@ module ApplicationTests
         def; end
       RUBY
 
-      error = capture(:stderr) { run_test_command("test/models/error_test.rb") }
+      error = capture(:stderr) { run_test_command("test/models/error_test.rb", stderr: true) }
       assert_match "syntax error", error
     end
 
@@ -91,13 +91,11 @@ module ApplicationTests
       create_test_file :unit, "baz_unit"
       create_test_file :controllers, "foobar_controller"
 
-      Dir.chdir(app_path) do
-        `bin/rails test:units`.tap do |output|
-          assert_match "FooTest", output
-          assert_match "BarHelperTest", output
-          assert_match "BazUnitTest", output
-          assert_match "3 runs, 3 assertions, 0 failures", output
-        end
+      rails("test:units").tap do |output|
+        assert_match "FooTest", output
+        assert_match "BarHelperTest", output
+        assert_match "BazUnitTest", output
+        assert_match "3 runs, 3 assertions, 0 failures", output
       end
     end
 
@@ -140,13 +138,11 @@ module ApplicationTests
       create_test_file :functional, "baz_functional"
       create_test_file :models, "foo"
 
-      Dir.chdir(app_path) do
-        `bin/rails test:functionals`.tap do |output|
-          assert_match "FooMailerTest", output
-          assert_match "BarControllerTest", output
-          assert_match "BazFunctionalTest", output
-          assert_match "3 runs, 3 assertions, 0 failures", output
-        end
+      rails("test:functionals").tap do |output|
+        assert_match "FooMailerTest", output
+        assert_match "BarControllerTest", output
+        assert_match "BazFunctionalTest", output
+        assert_match "3 runs, 3 assertions, 0 failures", output
       end
     end
 
@@ -524,11 +520,11 @@ module ApplicationTests
       create_test_file :models, "post", pass: false
 
       assert_match(/Interrupt/,
-        capture(:stderr) { run_test_command("test/models/post_test.rb --fail-fast") })
+        capture(:stderr) { run_test_command("test/models/post_test.rb --fail-fast", stderr: true) })
     end
 
     def test_raise_error_when_specified_file_does_not_exist
-      error = capture(:stderr) { run_test_command("test/not_exists.rb") }
+      error = capture(:stderr) { run_test_command("test/not_exists.rb", stderr: true) }
       assert_match(%r{cannot load such file.+test/not_exists\.rb}, error)
     end
 
@@ -554,14 +550,16 @@ module ApplicationTests
 
     def test_rails_db_create_all_restores_db_connection
       create_test_file :models, "account"
-      output = Dir.chdir(app_path) { `bin/rails db:create:all db:migrate && echo ".tables" | rails dbconsole` }
+      rails "db:create:all", "db:migrate"
+      output = Dir.chdir(app_path) { `echo ".tables" | rails dbconsole` }
       assert_match "ar_internal_metadata", output, "tables should be dumped"
     end
 
     def test_rails_db_create_all_restores_db_connection_after_drop
       create_test_file :models, "account"
-      Dir.chdir(app_path) { `bin/rails db:create:all` } # create all to avoid warnings
-      output = Dir.chdir(app_path) { `bin/rails db:drop:all db:create:all db:migrate && echo ".tables" | rails dbconsole` }
+      rails "db:create:all" # create all to avoid warnings
+      rails "db:drop:all", "db:create:all", "db:migrate"
+      output = Dir.chdir(app_path) { `echo ".tables" | rails dbconsole` }
       assert_match "ar_internal_metadata", output, "tables should be dumped"
     end
 
@@ -601,7 +599,7 @@ module ApplicationTests
         end
       RUBY
       assert_match(/warning: assigned but unused variable/,
-        capture(:stderr) { run_test_command("test/models/warnings_test.rb -w") })
+        capture(:stderr) { run_test_command("test/models/warnings_test.rb -w", stderr: true) })
     end
 
     def test_reset_sessions_before_rollback_on_system_tests
@@ -679,12 +677,12 @@ module ApplicationTests
     end
 
     private
-      def run_test_command(arguments = "test/unit/test_test.rb")
-        Dir.chdir(app_path) { `bin/rails t #{arguments}` }
+      def run_test_command(arguments = "test/unit/test_test.rb", **opts)
+        rails "t", *Shellwords.split(arguments), allow_failure: true, **opts
       end
 
       def create_model_with_fixture
-        script "generate model user name:string"
+        rails "generate", "model", "user", "name:string"
 
         app_file "test/fixtures/users.yml", <<-YAML.strip_heredoc
           vampire:
@@ -755,17 +753,17 @@ module ApplicationTests
       end
 
       def create_scaffold
-        script "generate scaffold user name:string"
-        Dir.chdir(app_path) { File.exist?("app/models/user.rb") }
+        rails "generate", "scaffold", "user", "name:string"
+        assert File.exist?("#{app_path}/app/models/user.rb")
         run_migration
       end
 
       def create_controller
-        script "generate controller admin/dashboard index"
+        rails "generate", "controller", "admin/dashboard", "index"
       end
 
       def run_migration
-        Dir.chdir(app_path) { `bin/rails db:migrate` }
+        rails "db:migrate"
       end
   end
 end
diff --git a/railties/test/application/test_test.rb b/railties/test/application/test_test.rb
index 7e2364c0a6..0a51e98656 100644
--- a/railties/test/application/test_test.rb
+++ b/railties/test/application/test_test.rb
@@ -102,7 +102,7 @@ module ApplicationTests
     end
 
     test "ruby schema migrations" do
-      output  = script("generate model user name:string")
+      output  = rails("generate", "model", "user", "name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
       app_file "test/models/user_test.rb", <<-RUBY
@@ -139,7 +139,7 @@ module ApplicationTests
     end
 
     test "sql structure migrations" do
-      output  = script("generate model user name:string")
+      output  = rails("generate", "model", "user", "name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
       app_file "test/models/user_test.rb", <<-RUBY
@@ -178,7 +178,7 @@ module ApplicationTests
     end
 
     test "sql structure migrations when adding column to existing table" do
-      output_1  = script("generate model user name:string")
+      output_1  = rails("generate", "model", "user", "name:string")
       version_1 = output_1.match(/(\d+)_create_users\.rb/)[1]
 
       app_file "test/models/user_test.rb", <<-RUBY
@@ -203,7 +203,7 @@ module ApplicationTests
 
       assert_successful_test_run("models/user_test.rb")
 
-      output_2  = script("generate migration add_email_to_users")
+      output_2  = rails("generate", "migration", "add_email_to_users")
       version_2 = output_2.match(/(\d+)_add_email_to_users\.rb/)[1]
 
       app_file "test/models/user_test.rb", <<-RUBY
@@ -231,7 +231,7 @@ module ApplicationTests
     # For now, the user has to synchronize the schema manually.
     # This test-case serves as a reminder for this use-case.
     test "manually synchronize test schema after rollback" do
-      output  = script("generate model user name:string")
+      output  = rails("generate", "model", "user", "name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
       app_file "test/models/user_test.rb", <<-RUBY
@@ -265,7 +265,7 @@ module ApplicationTests
 
       assert_successful_test_run "models/user_test.rb"
 
-      Dir.chdir(app_path) { `bin/rails db:test:prepare` }
+      rails "db:test:prepare"
 
       assert_unsuccessful_run "models/user_test.rb", <<-ASSERTION
 Expected: ["id", "name"]
@@ -274,7 +274,7 @@ Expected: ["id", "name"]
     end
 
     test "hooks for plugins" do
-      output  = script("generate model user name:string")
+      output  = rails("generate", "model", "user", "name:string")
       version = output.match(/(\d+)_create_users\.rb/)[1]
 
       app_file "lib/tasks/hooks.rake", <<-RUBY
@@ -334,7 +334,7 @@ Expected: ["id", "name"]
       end
 
       def run_test_file(name, options = {})
-        Dir.chdir(app_path) { `bin/rails test "#{app_path}/test/#{name}" 2>&1` }
+        rails "test", "#{app_path}/test/#{name}", allow_failure: true
       end
   end
 end
diff --git a/railties/test/application/version_test.rb b/railties/test/application/version_test.rb
index 62d3c7b254..ae85cf8f05 100644
--- a/railties/test/application/version_test.rb
+++ b/railties/test/application/version_test.rb
@@ -15,12 +15,12 @@ class VersionTest < ActiveSupport::TestCase
   end
 
   test "command works" do
-    output = Dir.chdir(app_path) { `bin/rails version` }
+    output = rails("version")
     assert_equal "Rails #{Rails.gem_version}\n", output
   end
 
   test "short-cut alias works" do
-    output = Dir.chdir(app_path) { `bin/rails -v` }
+    output = rails("-v")
     assert_equal "Rails #{Rails.gem_version}\n", output
   end
 end
diff --git a/railties/test/commands/secrets_test.rb b/railties/test/commands/secrets_test.rb
index a1213a57f8..66a81826e3 100644
--- a/railties/test/commands/secrets_test.rb
+++ b/railties/test/commands/secrets_test.rb
@@ -1,11 +1,12 @@
 # frozen_string_literal: true
 
 require "isolation/abstract_unit"
+require "env_helpers"
 require "rails/command"
 require "rails/commands/secrets/secrets_command"
 
 class Rails::Command::SecretsCommandTest < ActiveSupport::TestCase
-  include ActiveSupport::Testing::Isolation
+  include ActiveSupport::Testing::Isolation, EnvHelpers
 
   def setup
     build_app
@@ -36,14 +37,16 @@ class Rails::Command::SecretsCommandTest < ActiveSupport::TestCase
 
   private
     def run_edit_command(editor: "cat")
-      Dir.chdir(app_path) { `EDITOR="#{editor}" bin/rails secrets:edit` }
+      switch_env("EDITOR", editor) do
+        rails "secrets:edit"
+      end
     end
 
     def run_show_command
-      Dir.chdir(app_path) { `bin/rails secrets:show` }
+      rails "secrets:show"
     end
 
     def run_setup_command
-      Dir.chdir(app_path) { `bin/rails secrets:setup` }
+      rails "secrets:setup"
     end
 end
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 90c366ba17..a4c6fc4e68 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -236,10 +236,88 @@ module TestHelpers
       end
     end
 
-    def script(script)
-      Dir.chdir(app_path) do
-        `#{Gem.ruby} #{app_path}/bin/rails #{script}`
+    # Invoke a bin/rails command inside the app
+    #
+    # allow_failures:: true to return normally if the command exits with
+    #   a non-zero status. By default, this method will raise.
+    # stderr:: true to pass STDERR output straight to the "real" STDERR.
+    #   By default, the STDERR and STDOUT of the process will be
+    #   combined in the returned string.
+    # fork:: false to not use fork even when it's available. By default,
+    #   when possible, the command is executed in a fork of the current
+    #   process, avoiding the need to load core Rails libraries anew.
+    def rails(*args, allow_failure: false, stderr: false, fork: true)
+      args = args.flatten
+
+      command = "bin/rails #{Shellwords.join args}#{' 2>&1' unless stderr}"
+
+      # Don't fork if the environment has disabled it
+      fork = false if ENV["NO_FORK"]
+
+      # Don't fork if the runtime isn't able to
+      fork = false if !Process.respond_to?(:fork)
+
+      # Don't fork if we're re-invoking minitest
+      fork = false if args.first == "t" || args.grep(/\Atest(:|\z)/).any?
+
+      if fork
+        out_read, out_write = IO.pipe
+        if stderr
+          err_read, err_write = IO.pipe
+        else
+          err_write = out_write
+        end
+
+        pid = fork do
+          out_read.close
+          err_read.close if err_read
+
+          $stdin.reopen(File::NULL, "r")
+          $stdout.reopen(out_write)
+          $stderr.reopen(err_write)
+
+          at_exit do
+            case $!
+            when SystemExit
+              exit! $!.status
+            when nil
+              exit! 0
+            else
+              err_write.puts "#{$!.class}: #{$!}"
+              exit! 1
+            end
+          end
+
+          Rails.instance_variable_set :@_env, nil
+
+          $-v = $-w = false
+          Dir.chdir app_path unless Dir.pwd == app_path
+
+          ARGV.replace(args)
+          load "./bin/rails"
+
+          exit! 0
+        end
+
+        out_write.close
+
+        if err_read
+          err_write.close
+
+          $stderr.write err_read.read
+        end
+
+        output = out_read.read
+
+        Process.waitpid pid
+
+      else
+        output = `cd #{app_path}; #{command}`
       end
+
+      raise "rails command failed (#{$?.exitstatus}): #{command}\n#{output}" unless allow_failure || $?.success?
+
+      output
     end
 
     def add_to_top_of_config(str)
diff --git a/railties/test/secrets_test.rb b/railties/test/secrets_test.rb
index ff6f955a78..631c6a13fe 100644
--- a/railties/test/secrets_test.rb
+++ b/railties/test/secrets_test.rb
@@ -108,7 +108,7 @@ class Rails::SecretsTest < ActiveSupport::TestCase
         config.dereferenced_secret = Rails.application.secrets.some_secret
       end_of_config
 
-      assert_equal "yeah yeah\n", `bin/rails runner -e production "puts Rails.application.config.dereferenced_secret"`
+      assert_equal "yeah yeah\n", rails("runner", "-e", "production", "puts Rails.application.config.dereferenced_secret", fork: false)
     end
   end
 
@@ -141,7 +141,7 @@ class Rails::SecretsTest < ActiveSupport::TestCase
         assert_match(/production:\n\s*api_key: 00112233445566778899aabbccddeeff…\n/, File.read(tmp_path))
       end
 
-      assert_equal "00112233445566778899aabbccddeeff…\n", `bin/rails runner -e production "puts Rails.application.secrets.api_key"`
+      assert_equal "00112233445566778899aabbccddeeff…\n", rails("runner", "-e", "production", "puts Rails.application.secrets.api_key", fork: false)
     end
   end
 
@@ -158,7 +158,7 @@ class Rails::SecretsTest < ActiveSupport::TestCase
         assert_equal(secrets.dup.force_encoding(Encoding::ASCII_8BIT), IO.binread(tmp_path))
       end
 
-      assert_equal "00112233445566778899aabbccddeeff…\n", `bin/rails runner -e production "puts Rails.application.secrets.api_key"`
+      assert_equal "00112233445566778899aabbccddeeff…\n", rails("runner", "-e", "production", "puts Rails.application.secrets.api_key", fork: false)
     end
   end