Call system test driver per-instance rather than globally

Previously the system test subclasses would call `driven_by` when the
app booted and not again when the test was initialized which resulted in
the driver from whichever class was called last to be used in tests.

In rails/rails#28144 the `driven_by` method was changed to run `use` on
setup and `reset` on teardown. While this was a viable fix this really
pointed to the problem that system test `driven_by` was a global
setting, rather than a per-class setting.

To alieviate this problem calling the driver should be done on an
instance level, rather than on the global level. I added an `initialize`
method to `SystemTestCase` which will call `use` on the superclass
driver. Running the server has been moved to `start_application` so that
it only needs to be called once on boot and no options from `driven_by`
were being passed to it.

This required a largish rewrite of the tests. Each test needs to utilize
the subclass so that it can properly test the drivers.
`ActionDispatch::SystemTestCase` shouldn't be called directly anymore.

1 files changed, 3 insertions, 3 deletions

diff --git a/actionpack/test/dispatch/system_testing/driver_test.rb b/actionpack/test/dispatch/system_testing/driver_test.rb
index 96d598a7a3..8f8777b19f 100644
--- a/actionpack/test/dispatch/system_testing/driver_test.rb
+++ b/actionpack/test/dispatch/system_testing/driver_test.rb
@@ -8,10 +8,10 @@ class DriverTest < ActiveSupport::TestCase
   end
 
   test "initializing the driver with a browser" do
-    driver = ActionDispatch::SystemTesting::Driver.new(:selenium, using: :chrome, screen_size: [ 1400, 1400 ])
+    driver = ActionDispatch::SystemTesting::Driver.new(:selenium, using: :chrome, screen_size: [1400, 1400])
     assert_equal :selenium, driver.instance_variable_get(:@name)
-    assert_equal :chrome, driver.instance_variable_get(:@using)
-    assert_equal [ 1400, 1400 ], driver.instance_variable_get(:@screen_size)
+    assert_equal :chrome, driver.instance_variable_get(:@browser)
+    assert_equal [1400, 1400], driver.instance_variable_get(:@screen_size)
   end
 
   test "selenium? returns false if driver is poltergeist" do