tests: add tests to prove that Procfile tasks all work for every builder

Closes #8242

tests/unit/builder-railpack.bats

@@ -54,6 +54,43 @@ teardown() {
   assert_output_contains 'Successfully built image in'
 }
 
+@test "(builder-pack) run" {
+  run /bin/bash -c "dokku config:set $TEST_APP SECRET_KEY=fjdkslafjdk"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku builder:set $TEST_APP selected railpack"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run deploy_app python dokku@$DOKKU_DOMAIN:$TEST_APP inject_requirements_txt
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains 'create mise config'
+  assert_output_contains 'Successfully built image in'
+
+  run /bin/bash -c "dokku run $TEST_APP python task.py test"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "['task.py', 'test']"
+
+  run /bin/bash -c "dokku run $TEST_APP task"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "['task.py', 'test']"
+
+  run /bin/bash -c "dokku run $TEST_APP env"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains "SECRET_KEY=fjdkslafjdk"
+}
+
 inject_requirements_txt() {
   local APP="$1"
   local APP_REPO_DIR="$2"