feat: properly export env vars for cnb apps

They are not baked into the image like they are for herokuish, so we need to manually set them via --env. Additionally, due to newline constraints in docker, we need to use `--env=key` format to correctly pull the values into place.

tests/unit/ps-cnb.bats

@@ -0,0 +1,31 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+setup() {
+  global_setup
+  create_app
+}
+
+teardown() {
+  destroy_app
+  global_teardown
+}
+
+@test "(ps) cnb env vars" {
+  run /bin/bash -c "dokku config:set $TEST_APP DOKKU_CNB_EXPERIMENTAL=1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run deploy_app python dokku@dokku.me:$TEST_APP add_requirements_txt
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "curl $(dokku url $TEST_APP)/env"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains '"DOKKU_CNB_EXPERIMENTAL": "1"'
+}

tests/unit/test_helper.bash

@@ -513,6 +513,13 @@ add_release_command() {
   echo "release: touch /app/release.test" >> "$APP_REPO_DIR/Procfile"
 }
 
+add_requirements_txt() {
+  local APP="$1"
+  local APP_REPO_DIR="$2"
+  [[ -z "$APP" ]] && local APP="$TEST_APP"
+  echo "flask" >> "$APP_REPO_DIR/requirements.txt"
+}
+
 build_nginx_config() {
   # simulate nginx post-deploy
   dokku domains:setup "$TEST_APP"