retrieve sha from pull head when pull request branch deleted and fix tests

Author: lunny

modules/convert/pull.go

@@ -22,7 +22,6 @@ func ToAPIPullRequest(pr *models.PullRequest) *api.PullRequest {
 		baseBranch *git.Branch
 		headBranch *git.Branch
 		baseCommit *git.Commit
-		headCommit *git.Commit
 		err        error
 	)
 
@@ -99,22 +98,37 @@ func ToAPIPullRequest(pr *models.PullRequest) *api.PullRequest {
 		apiPullRequest.Head.RepoID = pr.HeadRepo.ID
 		apiPullRequest.Head.Repository = pr.HeadRepo.APIFormat(models.AccessModeNone)
 
-		headBranch, err = repo_module.GetBranch(pr.HeadRepo, pr.HeadBranch)
+		headGitRepo, err := git.OpenRepository(pr.HeadRepo.RepoPath())
+		if err != nil {
+			log.Error("OpenRepository[%s]: %v", pr.HeadRepo.RepoPath(), err)
+			return nil
+		}
+		defer headGitRepo.Close()
+
+		headBranch, err = headGitRepo.GetBranch(pr.HeadBranch)
 		if err != nil && !git.IsErrBranchNotExist(err) {
 			log.Error("GetBranch[%s]: %v", pr.HeadBranch, err)
 			return nil
 		}
 
-		if err == nil {
-			headCommit, err = headBranch.GetCommit()
+		if git.IsErrBranchNotExist(err) {
+			headCommitID, err := headGitRepo.GetRefCommitID(apiPullRequest.Head.Ref)
+			if err != nil && !git.IsErrNotExist(err) {
+				log.Error("GetCommit[%s]: %v", headBranch.Name, err)
+				return nil
+			}
+			if err == nil {
+				apiPullRequest.Head.Sha = headCommitID
+			}
+		} else {
+			commit, err := headBranch.GetCommit()
 			if err != nil && !git.IsErrNotExist(err) {
 				log.Error("GetCommit[%s]: %v", headBranch.Name, err)
 				return nil
 			}
-
 			if err == nil {
 				apiPullRequest.Head.Ref = pr.HeadBranch
-				apiPullRequest.Head.Sha = headCommit.ID.String()
+				apiPullRequest.Head.Sha = commit.ID.String()
 			}
 		}
 	}

modules/convert/pull_test.go

@@ -8,19 +8,26 @@ import (
 	"testing"
 
 	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/structs"
 
 	"github.com/stretchr/testify/assert"
 )
 
 func TestPullRequest_APIFormat(t *testing.T) {
 	//with HeadRepo
 	assert.NoError(t, models.PrepareTestDatabase())
+	headRepo := models.AssertExistsAndLoadBean(t, &models.Repository{ID: 1}).(*models.Repository)
 	pr := models.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 1}).(*models.PullRequest)
 	assert.NoError(t, pr.LoadAttributes())
 	assert.NoError(t, pr.LoadIssue())
 	apiPullRequest := ToAPIPullRequest(pr)
 	assert.NotNil(t, apiPullRequest)
-	assert.Nil(t, apiPullRequest.Head)
+	assert.EqualValues(t, &structs.PRBranchInfo{
+		Name:       "branch1",
+		Ref:        "refs/pull/2/head",
+		RepoID:     1,
+		Repository: headRepo.APIFormat(models.AccessModeNone),
+	}, apiPullRequest.Head)
 
 	//withOut HeadRepo
 	pr = models.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 1}).(*models.PullRequest)