fix json unmarshal error when list plguins (#888)

pkg/apisix/cluster.go

@@ -750,10 +750,15 @@ func (c *cluster) getList(ctx context.Context, url, resource string) ([]string,
 		return nil, err
 	}
 
-	var listResponse []string
+	var listResponse map[string]interface{}
 	dec := json.NewDecoder(resp.Body)
 	if err := dec.Decode(&listResponse); err != nil {
 		return nil, err
 	}
-	return listResponse, nil
+	res := make([]string, 0, len(listResponse))
+
+	for name := range listResponse {
+		res = append(res, name)
+	}
+	return res, nil
 }

pkg/apisix/plugin_test.go

@@ -19,6 +19,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"net/url"
+	"sort"
 	"strings"
 	"testing"
 
@@ -46,8 +47,13 @@ func (srv *fakeAPISIXPluginSrv) ServeHTTP(w http.ResponseWriter, r *http.Request
 		return
 	}
 
+	fakePluginsResp := make(map[string]interface{}, len(srv.plugins))
+	for _, fp := range srv.plugins {
+		fakePluginsResp[fp] = struct{}{}
+	}
+
 	if r.Method == http.MethodGet {
-		data, _ := json.Marshal(srv.plugins)
+		data, _ := json.Marshal(fakePluginsResp)
 		_, _ = w.Write(data)
 		w.WriteHeader(http.StatusOK)
 		return
@@ -101,6 +107,8 @@ func TestPluginClient(t *testing.T) {
 	objs, err := cli.List(context.Background())
 	assert.Nil(t, err)
 	assert.Len(t, objs, len(fakePluginNames))
+	sort.Strings(fakePluginNames)
+	sort.Strings(objs)
 	for i := range fakePluginNames {
 		assert.Equal(t, fakePluginNames[i], objs[i])
 	}