feat: introduce global merge message templates (#8347)

Allow for a directory `default_merge_message` in the `CustomPath` to be used as a fallback if no merge template is specified by the repository. Effectively being a global merge message template feature.

Resolves #6648

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8347
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: kochklops <kochklops@noreply.codeberg.org>
Co-committed-by: kochklops <kochklops@noreply.codeberg.org>

models/repo/git.go

@@ -29,6 +29,8 @@ const (
 	MergeStyleRebaseUpdate MergeStyle = "rebase-update-only"
 )
 
+var MergeStyles = []MergeStyle{MergeStyleMerge, MergeStyleRebase, MergeStyleRebaseMerge, MergeStyleSquash, MergeStyleFastForwardOnly, MergeStyleManuallyMerged, MergeStyleRebaseUpdate}
+
 type UpdateStyle string
 
 const (

modules/git/tests/repos/templates_repo/COMMIT_EDITMSG

@@ -0,0 +1 @@
+Initial

modules/git/tests/repos/templates_repo/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

modules/git/tests/repos/templates_repo/config

@@ -0,0 +1,5 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true
+	logallrefupdates = true

modules/git/tests/repos/templates_repo/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

modules/git/tests/repos/templates_repo/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

modules/git/tests/repos/templates_repo/info/refs

@@ -0,0 +1 @@
+45697427ce0595075c5c8efa42567f050208510d	refs/heads/master

modules/git/tests/repos/templates_repo/objects/info/packs

@@ -0,0 +1,2 @@
+P pack-abb44544ae19d590e95822e963f78d069d27ba9e.pack
+

modules/git/tests/repos/templates_repo/packed-refs

@@ -0,0 +1,2 @@
+# pack-refs with: peeled fully-peeled sorted 
+45697427ce0595075c5c8efa42567f050208510d refs/heads/master

services/pull/check.go

@@ -404,6 +404,10 @@ func CheckPRsForBaseBranch(ctx context.Context, baseRepo *repo_model.Repository,
 
 // Init runs the task queue to test all the checking status pull requests
 func Init() error {
+	if err := LoadMergeMessageTemplates(); err != nil {
+		return err
+	}
+
 	prPatchCheckerQueue = queue.CreateUniqueQueue(graceful.GetManager().ShutdownContext(), "pr_patch_checker", handler)
 
 	if prPatchCheckerQueue == nil {

services/pull/merge.go

@@ -35,6 +35,30 @@ import (
 	notify_service "forgejo.org/services/notify"
 )
 
+var mergeMessageTemplates = make(map[repo_model.MergeStyle]string, len(repo_model.MergeStyles))
+
+func LoadMergeMessageTemplates() error {
+	// Load templates for all known merge styles
+	for _, mergeStyle := range repo_model.MergeStyles {
+		templateFilename := filepath.Join(
+			setting.CustomPath,
+			"default_merge_message",
+			fmt.Sprintf("%s_TEMPLATE.md", strings.ToUpper(string(mergeStyle))),
+		)
+
+		content, err := os.ReadFile(templateFilename)
+		if err == nil {
+			mergeMessageTemplates[mergeStyle] = string(content)
+		} else if os.IsNotExist(err) {
+			// The file no longer exists, so delete any previous content
+			delete(mergeMessageTemplates, mergeStyle)
+		} else {
+			return err
+		}
+	}
+	return nil
+}
+
 // getMergeMessage composes the message used when merging a pull request.
 func getMergeMessage(ctx context.Context, baseGitRepo *git.Repository, pr *issues_model.PullRequest, mergeStyle repo_model.MergeStyle, extraVars map[string]string) (message, body string, err error) {
 	if err := pr.LoadBaseRepo(ctx); err != nil {
@@ -79,6 +103,13 @@ func getMergeMessage(ctx context.Context, baseGitRepo *git.Repository, pr *issue
 		if _, ok := err.(git.ErrNotExist); ok {
 			templateContent, err = commit.GetFileContent(templateFilepathGitea, setting.Repository.PullRequest.DefaultMergeMessageSize)
 		}
+
+		if _, ok := err.(git.ErrNotExist); ok {
+			if preloadedContent, ok := mergeMessageTemplates[mergeStyle]; ok {
+				templateContent, err = preloadedContent, nil
+			}
+		}
+
 		if err != nil {
 			if !git.IsErrNotExist(err) {
 				return "", "", err

services/pull/merge_test.go

@@ -4,9 +4,17 @@
 package pull
 
 import (
+	"os"
+	"path"
+	"strings"
 	"testing"
 
+	repo_model "forgejo.org/models/repo"
+	"forgejo.org/modules/setting"
+	"forgejo.org/modules/test"
+
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func Test_expandDefaultMergeMessage(t *testing.T) {
@@ -90,3 +98,51 @@ func TestAddCommitMessageTailer(t *testing.T) {
 	assert.Equal(t, "title\n\nTest-tailer: v1\nTest-tailer: v2", AddCommitMessageTrailer("title\n\nTest-tailer: v1", "Test-tailer", "v2"))
 	assert.Equal(t, "title\n\nTest-tailer: v1\nTest-tailer: v2", AddCommitMessageTrailer("title\n\nTest-tailer: v1\n", "Test-tailer", "v2"))
 }
+
+func prepareLoadMergeMessageTemplates(targetDir string) error {
+	for _, template := range []string{"MERGE", "REBASE", "REBASE-MERGE", "SQUASH", "MANUALLY-MERGED", "REBASE-UPDATE-ONLY"} {
+		file, err := os.Create(path.Join(targetDir, template+"_TEMPLATE.md"))
+		defer file.Close()
+
+		if err == nil {
+			_, err = file.WriteString("Contents for " + template)
+		}
+
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func TestLoadMergeMessageTemplates(t *testing.T) {
+	defer test.MockVariableValue(&setting.CustomPath, t.TempDir())()
+	templateTemp := path.Join(setting.CustomPath, "default_merge_message")
+
+	require.NoError(t, os.MkdirAll(templateTemp, 0o755))
+	require.NoError(t, prepareLoadMergeMessageTemplates(templateTemp))
+
+	testStyles := []repo_model.MergeStyle{
+		repo_model.MergeStyleMerge,
+		repo_model.MergeStyleRebase,
+		repo_model.MergeStyleRebaseMerge,
+		repo_model.MergeStyleSquash,
+		repo_model.MergeStyleManuallyMerged,
+		repo_model.MergeStyleRebaseUpdate,
+	}
+
+	// Load all templates
+	require.NoError(t, LoadMergeMessageTemplates())
+
+	// Check their correctness
+	assert.Len(t, mergeMessageTemplates, len(testStyles))
+	for _, mergeStyle := range testStyles {
+		assert.Equal(t, "Contents for "+strings.ToUpper(string(mergeStyle)), mergeMessageTemplates[mergeStyle])
+	}
+
+	// Unload all templates
+	require.NoError(t, os.RemoveAll(templateTemp))
+	require.NoError(t, LoadMergeMessageTemplates())
+	assert.Empty(t, mergeMessageTemplates)
+}

services/pull/pull_test.go

@@ -92,3 +92,39 @@ func TestPullRequest_GetDefaultMergeMessage_ExternalTracker(t *testing.T) {
 
 	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo2:branch2 into master", mergeMessage)
 }
+
+func TestPullRequest_GetDefaultMergeMessage_GlobalTemplate(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	pr := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{ID: 2})
+
+	require.NoError(t, pr.LoadBaseRepo(t.Context()))
+	gitRepo, err := gitrepo.OpenRepository(t.Context(), pr.BaseRepo)
+	require.NoError(t, err)
+	defer gitRepo.Close()
+
+	templateRepo, err := git.OpenRepository(t.Context(), "./../../modules/git/tests/repos/templates_repo")
+	require.NoError(t, err)
+	defer templateRepo.Close()
+
+	mergeMessageTemplates[repo_model.MergeStyleMerge] = "${PullRequestTitle} (${PullRequestReference})\n${PullRequestDescription}"
+
+	// Check template is used for Merge...
+	mergeMessage, body, err := GetDefaultMergeMessage(t.Context(), gitRepo, pr, repo_model.MergeStyleMerge)
+	require.NoError(t, err)
+
+	assert.Equal(t, "issue3 (#3)", mergeMessage)
+	assert.Equal(t, "content for the third issue", body)
+
+	// ...but not for RebaseMerge
+	mergeMessage, _, err = GetDefaultMergeMessage(t.Context(), gitRepo, pr, repo_model.MergeStyleRebaseMerge)
+	require.NoError(t, err)
+
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from branch2 into master", mergeMessage)
+
+	// ...and that custom Merge template takes priority
+	mergeMessage, body, err = GetDefaultMergeMessage(t.Context(), templateRepo, pr, repo_model.MergeStyleMerge)
+	require.NoError(t, err)
+
+	assert.Equal(t, "Default merge message template", mergeMessage)
+	assert.Equal(t, "This line was read from .forgejo/default_merge_message/MERGE_TEMPLATE.md", body)
+}