Support elastic search for code search (#10273)

* Support elastic search for code search

* Finished elastic search implementation and add some tests

* Enable test on drone and added docs

* Add new fields to elastic search

* Fix bug

* remove unused changes

* Use indexer alias to keep the gitea indexer version

* Improve codes

* Some code improvements

* The real indexer name changed to xxx.v1

Co-authored-by: zeripath <art27@cantab.net>

modules/indexer/code/indexer_test.go

@@ -0,0 +1,83 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package code
+
+import (
+	"path/filepath"
+	"testing"
+
+	"code.gitea.io/gitea/models"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMain(m *testing.M) {
+	models.MainTest(m, filepath.Join("..", "..", ".."))
+}
+
+func testIndexer(name string, t *testing.T, indexer Indexer) {
+	t.Run(name, func(t *testing.T) {
+		var repoID int64 = 1
+		err := index(indexer, repoID)
+		assert.NoError(t, err)
+		var (
+			keywords = []struct {
+				RepoIDs []int64
+				Keyword string
+				IDs     []int64
+				Langs   int
+			}{
+				{
+					RepoIDs: nil,
+					Keyword: "Description",
+					IDs:     []int64{repoID},
+					Langs:   1,
+				},
+				{
+					RepoIDs: []int64{2},
+					Keyword: "Description",
+					IDs:     []int64{},
+					Langs:   0,
+				},
+				{
+					RepoIDs: nil,
+					Keyword: "repo1",
+					IDs:     []int64{repoID},
+					Langs:   1,
+				},
+				{
+					RepoIDs: []int64{2},
+					Keyword: "repo1",
+					IDs:     []int64{},
+					Langs:   0,
+				},
+				{
+					RepoIDs: nil,
+					Keyword: "non-exist",
+					IDs:     []int64{},
+					Langs:   0,
+				},
+			}
+		)
+
+		for _, kw := range keywords {
+			t.Run(kw.Keyword, func(t *testing.T) {
+				total, res, langs, err := indexer.Search(kw.RepoIDs, "", kw.Keyword, 1, 10)
+				assert.NoError(t, err)
+				assert.EqualValues(t, len(kw.IDs), total)
+				assert.EqualValues(t, kw.Langs, len(langs))
+
+				var ids = make([]int64, 0, len(res))
+				for _, hit := range res {
+					ids = append(ids, hit.RepoID)
+					assert.EqualValues(t, "# repo1\n\nDescription for repo1", hit.Content)
+				}
+				assert.EqualValues(t, kw.IDs, ids)
+			})
+		}
+
+		assert.NoError(t, indexer.Delete(repoID))
+	})
+}