Append to existing trailers in generated squash commit message (#15980)

* Remove superfluous newline before Co-authored-by trailers

* Append to existing PR description trailer section

If the existing PR description message already contains a trailer section (e.g. Signed-off-by: ),
append to it instead of creating a new trailer section.

* Reuse compiled regexp

* Simplify regex and deal with trailing \n in PR description

* Add tests for CommitMessageTrailersPattern

- add support for Key:Value (no space after colon)
- add support for whitespace "folding"

* Update services/pull/pull_test.go

Co-authored-by: Norwin <noerw@users.noreply.github.com>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Norwin <noerw@users.noreply.github.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

1 files changed, 23 insertions, 0 deletions

diff --git a/services/pull/pull_test.go b/services/pull/pull_test.go
index 64920e3550..81627ebb77 100644
--- a/services/pull/pull_test.go
+++ b/services/pull/pull_test.go
@@ -5,4 +5,27 @@
 
 package pull
 
+import (
+	"testing"
+
+	"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"))
+}