pr: add function that checks and prepares PRs

common/config.go

@@ -39,6 +39,10 @@ const (
 
 	Permission_ForceMerge = "force-merge"
 	Permission_Group      = "release-engineering"
+
+	MergeModeFF      = "ff-only"
+	MergeModeReplace = "replace"
+	MergeModeDevel   = "devel"
 )
 
 type ConfigFile struct {
@@ -52,9 +56,9 @@ type ReviewGroup struct {
 }
 
 type QAConfig struct {
-	Name   string
+	Name              string
-	Origin string
+	Origin            string
-	Label  string // requires this gitea lable to be set or skipped
+	Label             string   // requires this gitea lable to be set or skipped
 	BuildDisableRepos []string // which repos to build disable in the new project
 }
 
@@ -88,7 +92,8 @@ type AutogitConfig struct {
 	Committers     []string // group in addition to Reviewers and Maintainers that can order the bot around, mostly as helper for factory-maintainers
 	Subdirs        []string // list of directories to sort submodules into. Needed b/c _manifest cannot list non-existent directories
 
-	Labels map[string]string // list of tags, if not default, to apply
+	Labels    map[string]string // list of tags, if not default, to apply
+	MergeMode string            // project merge mode
 
 	NoProjectGitPR     bool // do not automatically create project git PRs, just assign reviewers and assume somethign else creates the ProjectGit PR
 	ManualMergeOnly    bool // only merge with "Merge OK" comment by Project Maintainers and/or Package Maintainers and/or reviewers
@@ -183,6 +188,17 @@ func ReadWorkflowConfig(gitea GiteaFileContentAndRepoFetcher, git_project string
 		}
 	}
 	config.GitProjectName = config.GitProjectName + "#" + branch
+
+	// verify merge modes
+	switch config.MergeMode {
+	case MergeModeFF, MergeModeDevel, MergeModeReplace:
+		break // good results
+	case "":
+		config.MergeMode = MergeModeFF
+	default:
+		return nil, fmt.Errorf("Unsupported merge mode in %s: %s", git_project, config.MergeMode)
+	}
+
 	return config, nil
 }
 

common/config_test.go

@@ -342,3 +342,67 @@ func TestConfigPermissions(t *testing.T) {
 		})
 	}
 }
+
+func TestConfigMergeModeParser(t *testing.T) {
+	tests := []struct {
+		name      string
+		json      string
+		mergeMode string
+		wantErr   bool
+	}{
+		{
+			name:      "empty",
+			json:      "{}",
+			mergeMode: common.MergeModeFF,
+		},
+		{
+			name:      "ff-only",
+			json:      `{"MergeMode": "ff-only"}`,
+			mergeMode: common.MergeModeFF,
+		},
+		{
+			name:      "replace",
+			json:      `{"MergeMode": "replace"}`,
+			mergeMode: common.MergeModeReplace,
+		},
+		{
+			name:      "devel",
+			json:      `{"MergeMode": "devel"}`,
+			mergeMode: common.MergeModeDevel,
+		},
+		{
+			name:    "unsupported",
+			json:    `{"MergeMode": "invalid"}`,
+			wantErr: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			repo := models.Repository{
+				DefaultBranch: "master",
+			}
+
+			ctl := gomock.NewController(t)
+			gitea := mock_common.NewMockGiteaFileContentAndRepoFetcher(ctl)
+			gitea.EXPECT().GetRepositoryFileContent("foo", "bar", "", "workflow.config").Return([]byte(test.json), "abc", nil)
+			gitea.EXPECT().GetRepository("foo", "bar").Return(&repo, nil)
+
+			config, err := common.ReadWorkflowConfig(gitea, "foo/bar")
+			if test.wantErr {
+				if err == nil {
+					t.Fatal("Expected error, got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if config.MergeMode != test.mergeMode {
+				t.Errorf("Expected MergeMode %s, got %s", test.mergeMode, config.MergeMode)
+			}
+		})
+	}
+}

common/pr.go

@@ -552,6 +552,145 @@ func (rs *PRSet) IsApproved(gitea GiteaPRChecker, maintainers MaintainershipData
 	return is_manually_reviewed_ok
 }
 
+func (rs *PRSet) AddMergeCommit(git Git, remote string, pr int) bool {
+	prinfo := rs.PRs[pr]
+
+	LogDebug("Adding merge commit for %s", PRtoString(prinfo.PR))
+	if !prinfo.PR.AllowMaintainerEdit {
+		LogError(" PR is not editable by maintainer")
+		return false
+	}
+
+	repo := prinfo.PR.Base.Repo
+	head := prinfo.PR.Head
+	br := rs.Config.Branch
+	if len(br) == 0 {
+		br = prinfo.PR.Base.Name
+	}
+
+	msg := fmt.Sprintf("Merge branch '%s' into %s", br, head.Name)
+	if err := git.GitExec(repo.Name, "merge", "--no-ff", "--no-commit", "-X", "theirs", head.Sha); err != nil {
+		if err := git.GitExec(repo.Name, "merge", "--no-ff", "--no-commit", "--allow-unrelated-histories", "-X", "theirs", head.Sha); err != nil {
+			return false
+		}
+		LogError("WARNING: Merging unrelated histories")
+	}
+
+	// ensure only files that are in head.Sha are kept
+	git.GitExecOrPanic(repo.Name, "read-tree", "-m", head.Sha)
+	git.GitExecOrPanic(repo.Name, "commit", "-m", msg)
+	git.GitExecOrPanic(repo.Name, "clean", "-fxd")
+
+	if !IsDryRun {
+		git.GitExecOrPanic(repo.Name, "push", remote, "HEAD:"+head.Name)
+		prinfo.PR.Head.Sha = strings.TrimSpace(git.GitExecWithOutputOrPanic(repo.Name, "rev-list", "-1", "HEAD")) // need to update as it's pushed but pr not refetched
+	}
+
+	return true
+}
+
+func (rs *PRSet) HasMerge(git Git, pr int) bool {
+	prinfo := rs.PRs[pr]
+
+	repo := prinfo.PR.Base.Repo
+	head := prinfo.PR.Head
+	br := rs.Config.Branch
+	if len(br) == 0 {
+		br = prinfo.PR.Base.Name
+	}
+
+	parents, err := git.GitExecWithOutput(repo.Name, "show", "-s", "--format=%P", head.Sha)
+	if err == nil {
+		p := strings.Fields(strings.TrimSpace(parents))
+		if len(p) == 2 {
+			targetHead, _ := git.GitExecWithOutput(repo.Name, "rev-parse", "HEAD")
+			targetHead = strings.TrimSpace(targetHead)
+			if p[0] == targetHead || p[1] == targetHead {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func (rs *PRSet) PrepareForMerge(git Git) bool {
+	// verify that package can merge here. Checkout current target branch of each PRSet, make a temporary branch
+	// PR_#_mergetest and perform the merge based
+
+	if rs.Config.MergeMode == MergeModeDevel {
+		return true // always can merge as we set branch here, not merge anything
+	} else {
+		// make sure that all the package PRs are in mergeable state
+		for idx, prinfo := range rs.PRs {
+			if rs.IsPrjGitPR(prinfo.PR) {
+				continue
+			}
+
+			repo := prinfo.PR.Base.Repo
+			head := prinfo.PR.Head
+			br := rs.Config.Branch
+			if len(br) == 0 {
+				br = prinfo.PR.Base.Name
+			}
+
+			remote, err := git.GitClone(repo.Name, br, repo.SSHURL)
+			if err != nil {
+				return false
+			}
+			git.GitExecOrPanic(repo.Name, "fetch", remote, head.Sha)
+			switch rs.Config.MergeMode {
+			case MergeModeFF:
+				if err := git.GitExec(repo.Name, "merge-base", "--is-ancestor", "HEAD", head.Sha); err != nil {
+					return false
+				}
+			case MergeModeReplace:
+			Verify:
+				if err := git.GitExec(repo.Name, "merge-base", "--is-ancestor", "HEAD", head.Sha); err != nil {
+					if !rs.HasMerge(git, idx) {
+						forkRemote, err := git.GitClone(repo.Name, head.Name, head.Repo.SSHURL)
+						if err != nil {
+							LogError("Failed to clone head repo:", head.Name, head.Repo.SSHURL)
+							return false
+						}
+						LogDebug("Merge commit is missing and this is not FF merge possibility")
+						git.GitExecOrPanic(repo.Name, "checkout", remote+"/"+br)
+						if !rs.AddMergeCommit(git, forkRemote, idx) {
+							return false
+						}
+						if !IsDryRun {
+							goto Verify
+						}
+					}
+				}
+			}
+		}
+	}
+
+	// now we check project git if mergeable
+	prjgit_info, err := rs.GetPrjGitPR()
+	if err != nil {
+		return false
+	}
+	prjgit := prjgit_info.PR
+
+	_, _, prjgitBranch := rs.Config.GetPrjGit()
+	remote, err := git.GitClone(DefaultGitPrj, prjgitBranch, prjgit.Base.Repo.SSHURL)
+	if err != nil {
+		return false
+	}
+
+	testBranch := fmt.Sprintf("PR_%d_mergetest", prjgit.Index)
+	git.GitExecOrPanic(DefaultGitPrj, "fetch", remote, prjgit.Head.Sha)
+	if err := git.GitExec(DefaultGitPrj, "checkout", "-B", testBranch, prjgit.Base.Sha); err != nil {
+		return false
+	}
+	if err := git.GitExec(DefaultGitPrj, "merge", "--no-ff", "--no-commit", prjgit.Head.Sha); err != nil {
+		return false
+	}
+
+	return true
+}
+
 func (rs *PRSet) Merge(gitea GiteaReviewUnrequester, git Git) error {
 	prjgit_info, err := rs.GetPrjGitPR()
 	if err != nil {
@@ -690,8 +829,12 @@ func (rs *PRSet) Merge(gitea GiteaReviewUnrequester, git Git) error {
 		}
 		prinfo.RemoteName, err = git.GitClone(repo.Name, br, repo.SSHURL)
 		PanicOnError(err)
-		git.GitExecOrPanic(repo.Name, "fetch", prinfo.RemoteName, head.Sha)
+		if rs.Config.MergeMode == MergeModeDevel {
-		git.GitExecOrPanic(repo.Name, "merge", "--ff", head.Sha)
+			git.GitExecOrPanic(repo.Name, "checkout", "-B", br, head.Sha)
+		} else {
+			git.GitExecOrPanic(repo.Name, "fetch", prinfo.RemoteName, head.Sha)
+			git.GitExecOrPanic(repo.Name, "merge", "--ff", head.Sha)
+		}
 
 	}
 
@@ -708,7 +851,12 @@ func (rs *PRSet) Merge(gitea GiteaReviewUnrequester, git Git) error {
 		repo := prinfo.PR.Base.Repo
 
 		if !IsDryRun {
-			git.GitExecOrPanic(repo.Name, "push", prinfo.RemoteName)
+			params := []string{"push"}
+			if rs.Config.MergeMode == MergeModeDevel {
+				params = append(params, "-f")
+			}
+			params = append(params, prinfo.RemoteName)
+			git.GitExecOrPanic(repo.Name, params...)
 		} else {
 			LogInfo("*** WOULD push", repo.Name, "to", prinfo.RemoteName)
 		}

common/pr_test.go

@@ -2,6 +2,7 @@ package common_test
 
 import (
 	"errors"
+	"fmt"
 	"os"
 	"os/exec"
 	"path"
@@ -1228,7 +1229,7 @@ func TestPRMerge(t *testing.T) {
 						Owner: &models.User{
 							UserName: "org",
 						},
-						SSHURL: "file://" + path.Join(repoDir, "prjgit"),
+						SSHURL: "ssh://git@src.opensuse.org/org/prj.git",
 					},
 				},
 				Head: &models.PRBranchInfo{
@@ -1248,7 +1249,7 @@ func TestPRMerge(t *testing.T) {
 						Owner: &models.User{
 							UserName: "org",
 						},
-						SSHURL: "file://" + path.Join(cmd.Dir, "prjgit"),
+						SSHURL: "ssh://git@src.opensuse.org/org/prj.git",
 					},
 				},
 				Head: &models.PRBranchInfo{
@@ -1338,3 +1339,346 @@ func TestPRChanges(t *testing.T) {
 		})
 	}
 }
+
+func TestPRPrepareForMerge(t *testing.T) {
+	tests := []struct {
+		name     string
+		setup    func(*mock_common.MockGit, *models.PullRequest, *models.PullRequest)
+		config   *common.AutogitConfig
+		expected bool
+		editable bool
+	}{
+		{
+			name: "Success Devel",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeDevel,
+			},
+			setup:    func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {},
+			expected: true,
+		},
+		{
+			name: "Success FF",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeFF,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin", pkgPR.Head.Sha)
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", pkgPR.Head.Sha).Return(nil)
+
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "checkout", "-B", "PR_1_mergetest", prjPR.Base.Sha).Return(nil)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "--no-commit", prjPR.Head.Sha).Return(nil)
+			},
+			expected: true,
+		},
+		{
+			name: "Success Replace MergeCommit",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeReplace,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin", pkgPR.Head.Sha)
+				// merge-base fails initially
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", pkgPR.Head.Sha).Return(fmt.Errorf("not ancestor"))
+				// HasMerge returns true
+				m.EXPECT().GitExecWithOutput("pkg", "show", "-s", "--format=%P", pkgPR.Head.Sha).Return("parent1 target_head", nil)
+				m.EXPECT().GitExecWithOutput("pkg", "rev-parse", "HEAD").Return("target_head", nil)
+
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "checkout", "-B", "PR_1_mergetest", prjPR.Base.Sha).Return(nil)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "--no-commit", prjPR.Head.Sha).Return(nil)
+			},
+			expected: true,
+		},
+		{
+			name: "Merge Conflict in PrjGit",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeFF,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin", pkgPR.Head.Sha)
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", pkgPR.Head.Sha).Return(nil)
+
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "checkout", "-B", "PR_1_mergetest", prjPR.Base.Sha).Return(nil)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "--no-commit", prjPR.Head.Sha).Return(fmt.Errorf("conflict"))
+			},
+			expected: false,
+		},
+		{
+			name: "Not FF in PkgGit",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeFF,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin", pkgPR.Head.Sha)
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", pkgPR.Head.Sha).Return(fmt.Errorf("not ancestor"))
+			},
+			expected: false,
+		},
+		{
+			name: "Success Replace with AddMergeCommit",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeReplace,
+			},
+			editable: true,
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin", pkgPR.Head.Sha)
+				// First merge-base fails
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", pkgPR.Head.Sha).Return(fmt.Errorf("not ancestor"))
+				// HasMerge returns false
+				m.EXPECT().GitExecWithOutput("pkg", "show", "-s", "--format=%P", pkgPR.Head.Sha).Return("parent1", nil)
+				m.EXPECT().GitClone("pkg", pkgPR.Head.Name, pkgPR.Base.Repo.SSHURL).Return("origin_fork", nil)
+				// AddMergeCommit is called
+				m.EXPECT().GitExecOrPanic("pkg", "checkout", "origin/master")
+				m.EXPECT().GitExec("pkg", "merge", "--no-ff", "--no-commit", "-X", "theirs", pkgPR.Head.Sha).Return(nil)
+				m.EXPECT().GitExecOrPanic("pkg", "read-tree", "-m", pkgPR.Head.Sha)
+				m.EXPECT().GitExecOrPanic("pkg", "commit", "-m", gomock.Any())
+				m.EXPECT().GitExecOrPanic("pkg", "clean", "-fxd")
+				m.EXPECT().GitExecOrPanic("pkg", "push", "origin_fork", "HEAD:"+pkgPR.Head.Name)
+				m.EXPECT().GitExecWithOutputOrPanic("pkg", "rev-list", "-1", "HEAD").Return("new_pkg_head_sha")
+				// Second merge-base succeeds (after goto Verify)
+				m.EXPECT().GitExec("pkg", "merge-base", "--is-ancestor", "HEAD", "new_pkg_head_sha").Return(nil)
+
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "checkout", "-B", "PR_1_mergetest", prjPR.Base.Sha).Return(nil)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "--no-commit", prjPR.Head.Sha).Return(nil)
+			},
+			expected: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			prjPR := &models.PullRequest{
+				Index: 1,
+				Base: &models.PRBranchInfo{
+					Name: "master",
+					Sha:  "base_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "_ObsPrj",
+						SSHURL: "ssh://git@src.opensuse.org/org/_ObsPrj.git",
+					},
+				},
+				Head: &models.PRBranchInfo{
+					Sha: "head_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "_ObsPrj",
+						SSHURL: "ssh://git@src.opensuse.org/org/_ObsPrj.git",
+					},
+				},
+			}
+
+			pkgPR := &models.PullRequest{
+				Index: 2,
+				Base: &models.PRBranchInfo{
+					Name: "master",
+					Sha:  "pkg_base_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "pkg",
+						SSHURL: "ssh://git@src.opensuse.org/org/pkg.git",
+					},
+				},
+				Head: &models.PRBranchInfo{
+					Name: "branch_name",
+					Sha:  "pkg_head_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "pkg",
+						SSHURL: "ssh://git@src.opensuse.org/org/pkg.git",
+					},
+				},
+				AllowMaintainerEdit: test.editable,
+			}
+
+			ctl := gomock.NewController(t)
+			git := mock_common.NewMockGit(ctl)
+			test.setup(git, prjPR, pkgPR)
+
+			prset := &common.PRSet{
+				Config: test.config,
+				PRs: []*common.PRInfo{
+					{PR: prjPR},
+					{PR: pkgPR},
+				},
+			}
+
+			if res := prset.PrepareForMerge(git); res != test.expected {
+				t.Errorf("Expected %v, got %v", test.expected, res)
+			}
+		})
+	}
+}
+
+func TestPRMergeMock(t *testing.T) {
+	tests := []struct {
+		name   string
+		setup  func(*mock_common.MockGit, *models.PullRequest, *models.PullRequest)
+		config *common.AutogitConfig
+	}{
+		{
+			name: "Success FF",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeFF,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "-m", gomock.Any(), prjPR.Head.Sha).Return(nil)
+
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin_pkg", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "fetch", "origin_pkg", pkgPR.Head.Sha)
+				m.EXPECT().GitExecOrPanic("pkg", "merge", "--ff", pkgPR.Head.Sha)
+				m.EXPECT().GitExecOrPanic("pkg", "push", "origin_pkg")
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "push", "origin")
+			},
+		},
+		{
+			name: "Success Devel",
+			config: &common.AutogitConfig{
+				Organization:   "org",
+				GitProjectName: "org/_ObsPrj#master",
+				MergeMode:      common.MergeModeDevel,
+			},
+			setup: func(m *mock_common.MockGit, prjPR, pkgPR *models.PullRequest) {
+				m.EXPECT().GitClone("_ObsPrj", "master", prjPR.Base.Repo.SSHURL).Return("origin", nil)
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "fetch", "origin", prjPR.Head.Sha)
+				m.EXPECT().GitExec("_ObsPrj", "merge", "--no-ff", "-m", gomock.Any(), prjPR.Head.Sha).Return(nil)
+
+				m.EXPECT().GitClone("pkg", "master", pkgPR.Base.Repo.SSHURL).Return("origin_pkg", nil)
+				m.EXPECT().GitExecOrPanic("pkg", "checkout", "-B", "master", pkgPR.Head.Sha)
+				m.EXPECT().GitExecOrPanic("pkg", "push", "-f", "origin_pkg")
+				m.EXPECT().GitExecOrPanic("_ObsPrj", "push", "origin")
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			prjPR := &models.PullRequest{
+				Index: 1,
+				Base: &models.PRBranchInfo{
+					Name: "master",
+					Sha:  "prj_base_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "_ObsPrj",
+						SSHURL: "ssh://git@src.opensuse.org/org/_ObsPrj.git",
+					},
+				},
+				Head: &models.PRBranchInfo{
+					Sha: "prj_head_sha",
+				},
+			}
+			pkgPR := &models.PullRequest{
+				Index: 2,
+				Base: &models.PRBranchInfo{
+					Name: "master",
+					Sha:  "pkg_base_sha",
+					Repo: &models.Repository{
+						Owner:  &models.User{UserName: "org"},
+						Name:   "pkg",
+						SSHURL: "ssh://git@src.opensuse.org/org/pkg.git",
+					},
+				},
+				Head: &models.PRBranchInfo{
+					Sha: "pkg_head_sha",
+				},
+			}
+
+			ctl := gomock.NewController(t)
+			git := mock_common.NewMockGit(ctl)
+			reviewUnrequestMock := mock_common.NewMockGiteaReviewUnrequester(ctl)
+			reviewUnrequestMock.EXPECT().UnrequestReview(gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any()).AnyTimes().Return(nil)
+
+			test.setup(git, prjPR, pkgPR)
+
+			prset := &common.PRSet{
+				Config: test.config,
+				PRs: []*common.PRInfo{
+					{PR: prjPR},
+					{PR: pkgPR},
+				},
+			}
+
+			if err := prset.Merge(reviewUnrequestMock, git); err != nil {
+				t.Errorf("Unexpected error: %v", err)
+			}
+		})
+	}
+}
+
+func TestPRAddMergeCommit(t *testing.T) {
+	pkgPR := &models.PullRequest{
+		Index: 2,
+		Base: &models.PRBranchInfo{
+			Name: "master",
+			Sha:  "pkg_base_sha",
+			Repo: &models.Repository{
+				Owner:  &models.User{UserName: "org"},
+				Name:   "pkg",
+				SSHURL: "ssh://git@src.opensuse.org/org/pkg.git",
+			},
+		},
+		Head: &models.PRBranchInfo{
+			Name: "branch_name",
+			Sha:  "pkg_head_sha",
+		},
+		AllowMaintainerEdit: true,
+	}
+
+	config := &common.AutogitConfig{
+		Organization:   "org",
+		GitProjectName: "org/_ObsPrj#master",
+		MergeMode:      common.MergeModeReplace,
+	}
+
+	ctl := gomock.NewController(t)
+	git := mock_common.NewMockGit(ctl)
+
+	git.EXPECT().GitExec("pkg", "merge", "--no-ff", "--no-commit", "-X", "theirs", pkgPR.Head.Sha).Return(nil)
+	git.EXPECT().GitExecOrPanic("pkg", "read-tree", "-m", pkgPR.Head.Sha)
+	git.EXPECT().GitExecOrPanic("pkg", "commit", "-m", gomock.Any())
+	git.EXPECT().GitExecOrPanic("pkg", "clean", "-fxd")
+	git.EXPECT().GitExecOrPanic("pkg", "push", "origin", "HEAD:branch_name")
+	git.EXPECT().GitExecWithOutputOrPanic("pkg", "rev-list", "-1", "HEAD").Return("new_head_sha")
+
+	prset := &common.PRSet{
+		Config: config,
+		PRs: []*common.PRInfo{
+			{PR: &models.PullRequest{}}, // prjgit at index 0
+			{PR: pkgPR},                 // pkg at index 1
+		},
+	}
+
+	if res := prset.AddMergeCommit(git, "origin", 1); !res {
+		t.Errorf("Expected true, got %v", res)
+	}
+}
+

workflow-pr/README.md

@@ -94,6 +94,19 @@ Package Deletion Requests
   If you wish to re-add a package, create a new PrjGit PR which adds again the submodule on the branch that has the "-removed" suffix. The bot will automatically remove this suffix from the project branch in the pool.
 
 
+Merge Modes
+-----------
+
+| Merge Mode | Description
+|------------|--------------------------------------------------------------------------------
+| ff-only    | Only allow --ff-only merges in the package branch. This is best suited for
+|            | devel projects and openSUSE Tumbleweed development, where history should be linear
+| replace    | Merge is done via `-X theirs` strategy and old files are removed in the merge.
+|            | This works well for downstream codestreams, like Leap, that would update their branch
+|            | using latest version.
+| devel      | No merge, just set the project branch to PR HEAD. This is suitable for downstream
+|            | projects like Leap during development cycle, where keeping maintenance history is not important
+
 Labels
 ------
 

workflow-pr/pr_processor.go

@@ -406,6 +406,12 @@ func (pr *PRProcessor) Process(req *models.PullRequest) error {
 	}
 	common.LogInfo("fetched PRSet of size:", len(prset.PRs))
 
+	if !prset.PrepareForMerge(git) {
+		common.LogError("PRs are NOT mergeable.")
+	} else {
+		common.LogInfo("PRs are in mergeable state.")
+	}
+
 	prjGitPRbranch := prGitBranchNameForPR(prRepo, prNo)
 	prjGitPR, err := prset.GetPrjGitPR()
 	if err == common.PRSet_PrjGitMissing {