feat: Real docker-based testing

This pull request switches testing to use an actual docker daemon, vs mocking everything out.

It may also catch actual breaking issues in our tests, which is great!

tests/service_clone.bats

@@ -2,34 +2,37 @@
 load test_helper
 
 setup() {
-  export ECHO_DOCKER_COMMAND="false"
-  dokku "$PLUGIN_COMMAND_PREFIX:create" l >&2
+  dokku "$PLUGIN_COMMAND_PREFIX:create" l
 }
 
 teardown() {
-  export ECHO_DOCKER_COMMAND="false"
-  dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" l >&2
+  dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" l
 }
 
 @test "($PLUGIN_COMMAND_PREFIX:clone) error when there are no arguments" {
   run dokku "$PLUGIN_COMMAND_PREFIX:clone"
   assert_contains "${lines[*]}" "Please specify a valid name for the service"
+  assert_failure
 }
 
 @test "($PLUGIN_COMMAND_PREFIX:clone) error when service does not exist" {
   run dokku "$PLUGIN_COMMAND_PREFIX:clone" not_existing_service new_service
   assert_contains "${lines[*]}" "service not_existing_service does not exist"
+  assert_failure
 }
 
 @test "($PLUGIN_COMMAND_PREFIX:clone) error when new service isn't provided" {
   run dokku "$PLUGIN_COMMAND_PREFIX:clone" l
   assert_contains "${lines[*]}" "Please specify a name for the new service"
+  assert_failure
 }
 
 @test "($PLUGIN_COMMAND_PREFIX:clone) error when new service already exists" {
   dokku "$PLUGIN_COMMAND_PREFIX:create" new_service
   run dokku "$PLUGIN_COMMAND_PREFIX:clone" l new_service
   assert_contains "${lines[*]}" "service new_service already exists"
+  assert_failure
+
   dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" new_service
 }
 
@@ -38,5 +41,7 @@ teardown() {
   [[ -f $PLUGIN_DATA_ROOT/new_service/ID ]]
   assert_contains "${lines[*]}" "Copying data from l to new_service"
   assert_contains "${lines[*]}" "Done"
-}
+  assert_success
 
+  dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" new_service
+}