添加 mysql redis postgres 插件

plugins/postgres/tests/hook_pre_delete.bats

@@ -0,0 +1,20 @@
+#!/usr/bin/env bats
+load test_helper
+
+setup() {
+  dokku apps:create my-app
+  dokku "$PLUGIN_COMMAND_PREFIX:create" ls
+  dokku "$PLUGIN_COMMAND_PREFIX:link" ls my-app >&2
+}
+
+teardown() {
+  dokku "$PLUGIN_COMMAND_PREFIX:unlink" ls my-app >&2
+  dokku --force "$PLUGIN_COMMAND_PREFIX:destroy" ls
+  dokku --force apps:destroy my-app || true
+}
+
+@test "($PLUGIN_COMMAND_PREFIX:hook:pre-delete) removes app from links file when destroying app" {
+  [[ -n $(<"$PLUGIN_DATA_ROOT/ls/LINKS") ]]
+  dokku --force apps:destroy my-app
+  [[ -z $(<"$PLUGIN_DATA_ROOT/ls/LINKS") ]]
+}