Fix GetPluginStatus in a non-cluster environment (#15363)

app/plugin_api_tests/test_get_plugin_status_plugin/main.go

@@ -0,0 +1,39 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package main
+
+import (
+	"github.com/mattermost/mattermost-server/v5/app/plugin_api_tests"
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/plugin"
+)
+
+type MyPlugin struct {
+	plugin.MattermostPlugin
+	configuration plugin_api_tests.BasicConfig
+}
+
+func (p *MyPlugin) OnConfigurationChange() error {
+	if err := p.API.LoadPluginConfiguration(&p.configuration); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (p *MyPlugin) MessageWillBePosted(c *plugin.Context, post *model.Post) (*model.Post, string) {
+	status, err := p.API.GetPluginStatus("test_get_plugin_status_plugin")
+	if err != nil {
+		return nil, err.Error()
+	}
+
+	if status.State != model.PluginStateRunning {
+		return nil, "State is not running"
+	}
+
+	return nil, "OK"
+}
+
+func main() {
+	plugin.ClientMain(&MyPlugin{})
+}