fix(pull): preserve squash message trailers and additional commit messages (#37954)

* Closes #37950
* Closes #37946
* Fixes https://github.com/go-gitea/gitea/issues/37529

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/pull/pull_test.go

@@ -11,28 +11,33 @@ import (
 	repo_model "gitea.dev/models/repo"
 	"gitea.dev/models/unit"
 	"gitea.dev/models/unittest"
+	"gitea.dev/modules/git"
 	"gitea.dev/modules/gitrepo"
+	"gitea.dev/modules/setting"
+	"gitea.dev/modules/test"
 
 	"github.com/stretchr/testify/assert"
 )
 
 // TODO TestPullRequest_PushToBaseRepo
 
-func TestPullRequest_CommitMessageTrailersPattern(t *testing.T) {
-	// Not a valid trailer section
-	assert.False(t, commitMessageTrailersPattern.MatchString(""))
-	assert.False(t, commitMessageTrailersPattern.MatchString("No trailer."))
-	assert.False(t, commitMessageTrailersPattern.MatchString("Signed-off-by: Bob <bob@example.com>\nNot a trailer due to following text."))
-	assert.False(t, commitMessageTrailersPattern.MatchString("Message body not correctly separated from trailer section by empty line.\nSigned-off-by: Bob <bob@example.com>"))
-	// Valid trailer section
-	assert.True(t, commitMessageTrailersPattern.MatchString("Signed-off-by: Bob <bob@example.com>"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Signed-off-by: Bob <bob@example.com>\nOther-Trailer: Value"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Message body correctly separated from trailer section by empty line.\n\nSigned-off-by: Bob <bob@example.com>"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Multiple trailers.\n\nSigned-off-by: Bob <bob@example.com>\nOther-Trailer: Value"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Newline after trailer section.\n\nSigned-off-by: Bob <bob@example.com>\n"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("No space after colon is accepted.\n\nSigned-off-by:Bob <bob@example.com>"))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Additional whitespace is accepted.\n\nSigned-off-by \t :  \tBob   <bob@example.com>   "))
-	assert.True(t, commitMessageTrailersPattern.MatchString("Folded value.\n\nFolded-trailer: This is\n a folded\n   trailer value\nOther-Trailer: Value"))
+func TestPullRequest_FormatSquashMergeCommitMessages(t *testing.T) {
+	oldest := &git.Commit{CommitMessage: git.CommitMessage{MessageRaw: "commit msg 1"}}
+	newest := &git.Commit{CommitMessage: git.CommitMessage{MessageRaw: "commit msg 2\n\nCommit description."}}
+
+	defer test.MockVariableValue(&setting.Repository.PullRequest.DefaultMergeMessageSize, 0)()
+
+	assert.Equal(t, "* commit msg 1\n\n* commit msg 2\n\nCommit description.\n\n", formatSquashMergeCommitMessages([]*git.Commit{newest, oldest}))
+
+	utf8Msg := &git.Commit{CommitMessage: git.CommitMessage{MessageRaw: "🌞"}}
+	setting.Repository.PullRequest.DefaultMergeMessageSize = 3
+	assert.Equal(t, "* ...\n\n", formatSquashMergeCommitMessages([]*git.Commit{utf8Msg}))
+	setting.Repository.PullRequest.DefaultMergeMessageSize = 4
+	assert.Equal(t, "* ...\n\n", formatSquashMergeCommitMessages([]*git.Commit{utf8Msg}))
+	setting.Repository.PullRequest.DefaultMergeMessageSize = 5
+	assert.Equal(t, "* ...\n\n", formatSquashMergeCommitMessages([]*git.Commit{utf8Msg}))
+	setting.Repository.PullRequest.DefaultMergeMessageSize = 6
+	assert.Equal(t, "* 🌞\n\n", formatSquashMergeCommitMessages([]*git.Commit{utf8Msg}))
 }
 
 func TestPullRequest_GetDefaultMergeMessage_InternalTracker(t *testing.T) {
@@ -88,3 +93,27 @@ func TestPullRequest_GetDefaultMergeMessage_ExternalTracker(t *testing.T) {
 
 	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo2:branch2 into master", mergeMessage)
 }
+
+func TestBuildSquashMergeCommitMessages(t *testing.T) {
+	cases := []struct {
+		msg       string
+		coAuthors []string
+		expected  string
+	}{
+		{"title", nil, "title"},
+		{"title", []string{"the-user"}, "title\n\n---------\n\nCo-authored-by: the-user\n"},
+		{"title\n\n", []string{"the-user"}, "title\n\n---------\n\nCo-authored-by: the-user\n"},
+		{"title\n\nKey: val", []string{"the-user"}, "title\n\nKey: val\nCo-authored-by: the-user\n"},
+		{"title\n\n----\nKey: val", []string{"the-user"}, "title\n\n----\nKey: val\nCo-authored-by: the-user\n"},
+		{"title\n\n----\nKey: val\n\n", []string{"the-user"}, "title\n\n----\nKey: val\nCo-authored-by: the-user\n"},
+
+		{"title\n\nbody", nil, "title\n\nbody"},
+		{"title\n\nbody", []string{"the-user"}, "title\n\nbody\n\n---------\n\nCo-authored-by: the-user\n"},
+		{"title\n\nbody\n\nKey: val", []string{"the-user"}, "title\n\nbody\n\nKey: val\nCo-authored-by: the-user\n"},
+		{"title\n\nbody\n\n----\nKey: val", []string{"the-user"}, "title\n\nbody\n\n----\nKey: val\nCo-authored-by: the-user\n"},
+	}
+	for _, c := range cases {
+		msg := buildSquashMergeCommitMessages(c.msg, c.coAuthors)
+		assert.Equal(t, c.expected, msg, "msg: %s", c.msg)
+	}
+}