Add tests for every implemented command

tests/service_destroy.bats

@@ -0,0 +1,27 @@
+#!/usr/bin/env bats
+load test_helper
+
+@test "($PLUGIN_COMMAND_PREFIX:destroy) success with --force" {
+  dokku "$PLUGIN_COMMAND_PREFIX:create" l
+  run dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" l
+  assert_contains "${lines[*]}" "container deleted: l"
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:destroy) error when there are no arguments" {
+  run dokku "$PLUGIN_COMMAND_PREFIX:destroy"
+  assert_contains "${lines[*]}" "Please specify a name for the service"
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:destroy) error when container does not exist" {
+  run dokku "$PLUGIN_COMMAND_PREFIX:destroy" non_existing_container
+  assert_contains "${lines[*]}" "service non_existing_container does not exist"
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:destroy) error when container is linked to an app" {
+  dokku "$PLUGIN_COMMAND_PREFIX:create" l
+  dokku apps:create app
+  dokku "$PLUGIN_COMMAND_PREFIX:link" l app
+  run dokku "$PLUGIN_COMMAND_PREFIX:destroy" l
+  assert_contains "${lines[*]}" "Cannot delete linked service"
+  rm "$DOKKU_ROOT/app" -rf
+}