[GITEA] GetScheduledMergeByPullID may involve a system user

Refs: https://codeberg.org/forgejo/forgejo/issues/1897
(cherry picked from commit ddc3c22558)
(cherry picked from commit a7fe969b93)
(cherry picked from commit 62bda95774)
(cherry picked from commit 8149a822c7)
(cherry picked from commit 9ed4e685eb)
(cherry picked from commit 4f072b4f80)

models/pull/automerge.go

@@ -74,7 +74,7 @@ func GetScheduledMergeByPullID(ctx context.Context, pullID int64) (bool, *AutoMe
 		return false, nil, err
 	}
 
-	doer, err := user_model.GetUserByID(ctx, scheduledPRM.DoerID)
+	doer, err := user_model.GetPossibleUserByID(ctx, scheduledPRM.DoerID)
 	if err != nil {
 		return false, nil, err
 	}

tests/integration/forgejo_git_test.go

@@ -0,0 +1,139 @@
+// Copyright Earl Warren <contact@earl-warren.org>
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"testing"
+	"time"
+
+	actions_model "code.gitea.io/gitea/models/actions"
+	auth_model "code.gitea.io/gitea/models/auth"
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestActionsUserGit(t *testing.T) {
+	onGiteaRun(t, testActionsUserGit)
+}
+
+func NewActionsUserTestContext(t *testing.T, username, reponame string) APITestContext {
+	t.Helper()
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{Name: reponame})
+	repoOwner := unittest.AssertExistsAndLoadBean(t, &user_model.User{Name: username})
+
+	task := unittest.AssertExistsAndLoadBean(t, &actions_model.ActionTask{ID: 47})
+	task.RepoID = repo.ID
+	task.OwnerID = repoOwner.ID
+	task.GenerateToken()
+
+	actions_model.UpdateTask(db.DefaultContext, task)
+	return APITestContext{
+		Session:  emptyTestSession(t),
+		Token:    task.Token,
+		Username: username,
+		Reponame: reponame,
+	}
+}
+
+func testActionsUserGit(t *testing.T, u *url.URL) {
+	username := "user2"
+	reponame := "repo1"
+	httpContext := NewAPITestContext(t, username, reponame, auth_model.AccessTokenScopeWriteRepository, auth_model.AccessTokenScopeWriteUser)
+
+	for _, testCase := range []struct {
+		name string
+		head string
+		ctx  APITestContext
+	}{
+		{
+			name: "UserTypeIndividual",
+			head: "individualhead",
+			ctx:  httpContext,
+		},
+		{
+			name: "ActionsUser",
+			head: "actionsuserhead",
+			ctx:  NewActionsUserTestContext(t, username, reponame),
+		},
+	} {
+		t.Run("CreatePR "+testCase.name, func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			dstPath := t.TempDir()
+			u.Path = httpContext.GitPath()
+			u.User = url.UserPassword(httpContext.Username, userPassword)
+			t.Run("Clone", doGitClone(dstPath, u))
+			t.Run("PopulateBranch", doActionsUserPopulateBranch(dstPath, &httpContext, "master", testCase.head))
+			t.Run("CreatePR", doActionsUserPR(httpContext, testCase.ctx, "master", testCase.head))
+		})
+	}
+}
+
+func doActionsUserPopulateBranch(dstPath string, ctx *APITestContext, baseBranch, headBranch string) func(t *testing.T) {
+	return func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		t.Run("CreateHeadBranch", doGitCreateBranch(dstPath, headBranch))
+
+		t.Run("AddCommit", func(t *testing.T) {
+			err := os.WriteFile(path.Join(dstPath, "test_file"), []byte("## test content"), 0o666)
+			if !assert.NoError(t, err) {
+				return
+			}
+
+			err = git.AddChanges(dstPath, true)
+			assert.NoError(t, err)
+
+			err = git.CommitChanges(dstPath, git.CommitChangesOptions{
+				Committer: &git.Signature{
+					Email: "user2@example.com",
+					Name:  "user2",
+					When:  time.Now(),
+				},
+				Author: &git.Signature{
+					Email: "user2@example.com",
+					Name:  "user2",
+					When:  time.Now(),
+				},
+				Message: "Testing commit 1",
+			})
+			assert.NoError(t, err)
+		})
+
+		t.Run("Push", func(t *testing.T) {
+			err := git.NewCommand(git.DefaultContext, "push", "origin").AddDynamicArguments("HEAD:refs/heads/" + headBranch).Run(&git.RunOpts{Dir: dstPath})
+			assert.NoError(t, err)
+		})
+	}
+}
+
+func doActionsUserPR(ctx, doerCtx APITestContext, baseBranch, headBranch string) func(t *testing.T) {
+	return func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		var pr api.PullRequest
+		var err error
+
+		// Create a test pullrequest
+		t.Run("CreatePullRequest", func(t *testing.T) {
+			pr, err = doAPICreatePullRequest(doerCtx, ctx.Username, ctx.Reponame, baseBranch, headBranch)(t)
+			assert.NoError(t, err)
+		})
+		doerCtx.ExpectedCode = http.StatusCreated
+		t.Run("AutoMergePR", doAPIAutoMergePullRequest(doerCtx, ctx.Username, ctx.Reponame, pr.Index))
+		// Ensure the PR page works
+		t.Run("EnsureCanSeePull", doEnsureCanSeePull(ctx, pr))
+	}
+}