Update comment message and add test case

Signed-off-by: Lukasz Gryglicki <lgryglicki@cncf.io>

Assisted by [OpenAI](https://platform.openai.com/)

Assisted by [GitHub Copilot](https://github.com/features/copilot)

Author: lukaszgryglicki

cla-backend-go/github/github_repository.go

@@ -53,6 +53,8 @@ Supported |Co-authored-by:| formats include:
 4) |Anything <other-email>| - it will locate your GitHub user by |other-email| part but only if that email was used before for any other CLA as a main commit author.
 5) |login <any-valid-email>| - it will locate your GitHub user by |login| part, note that |login| part must be at least 3 characters long.
 
+Alternatively, if the co-author should not be included, remove the |Co-authored-by:| line from the commit message.
+
 Please update your commit message(s) by doing |git commit --amend| and then |git push [--force]| and then request re-running CLA check via commenting on this pull request:
 
 |||

cla-backend-go/github/github_repository_test.go

@@ -0,0 +1,62 @@
+// Copyright The Linux Foundation and each contributor to CommunityBridge.
+// SPDX-License-Identifier: MIT
+
+package github
+
+import (
+	"testing"
+
+	gh "github.com/google/go-github/v37/github"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetCommentBodyIncludesCoAuthorRemovalGuidance(t *testing.T) {
+	signed := []*UserCommitSummary{{
+		SHA: "abc1234xyz-123",
+		CommitAuthor: &gh.User{
+			ID:    gh.Int64(1234),
+			Login: gh.String("login_value"),
+			Name:  gh.String("author name"),
+			Email: gh.String("foo@bar.com"),
+		},
+		Affiliated: true,
+		Authorized: true,
+	}}
+
+	missing := []*UserCommitSummary{{
+		SHA: "some_other_sha",
+		CommitAuthor: &gh.User{
+			ID:    gh.Int64(123456),
+			Login: gh.String("login_value2"),
+			Name:  gh.String("author name2"),
+			Email: gh.String("foo2@bar.com"),
+		},
+		Affiliated: false,
+		Authorized: false,
+	}}
+
+	body := getCommentBody("github", "https://foo.com", signed, missing, true)
+
+	assert.Contains(t, body, "One or more co-authors of this pull request were not found")
+	assert.Contains(t, body, "Alternatively, if the co-author should not be included, remove the `Co-authored-by:` line from the commit message.")
+	assert.NotContains(t, body, "|Co-authored-by:|")
+}
+
+func TestGetCommentBodyOmitsCoAuthorRemovalGuidanceWhenNoCoAuthorIsMissing(t *testing.T) {
+	missing := []*UserCommitSummary{{
+		SHA: "some_other_sha",
+		CommitAuthor: &gh.User{
+			ID:    gh.Int64(123456),
+			Login: gh.String("login_value2"),
+			Name:  gh.String("author name2"),
+			Email: gh.String("foo2@bar.com"),
+		},
+		Affiliated: false,
+		Authorized: false,
+	}}
+
+	body := getCommentBody("github", "https://foo.com", nil, missing, false)
+
+	assert.NotContains(t, body, "One or more co-authors of this pull request were not found")
+	assert.NotContains(t, body, "Alternatively, if the co-author should not be included, remove the `Co-authored-by:` line from the commit message.")
+}

cla-backend/cla/tests/unit/test_user_commit_summary.py

@@ -74,3 +74,4 @@ def test_user_commit_summary_get_comment_body_missing_co_authors(self) -> None:
         self.assertTrue(':white_check_mark:' in body)
         self.assertTrue(':x:' in body)
         self.assertTrue('One or more co-authors of this pull request were not found' in body)
+        self.assertTrue('Alternatively, if the co-author should not be included, remove the `Co-authored-by:` line from the commit message.' in body)

cla-backend/cla/utils.py

@@ -53,6 +53,8 @@
 4) `Anything <other-email>` - it will locate your GitHub user by `other-email` part but only if that email was used before for any other CLA as a main commit author.
 5) `login <any-valid-email>` - it will locate your GitHub user by `login` part, note that `login` part must be at least 3 characters long.
 
+Alternatively, if the co-author should not be included, remove the `Co-authored-by:` line from the commit message.
+
 Please update your commit message(s) by doing `git commit --amend` and then `git push [--force]` and then request re-running CLA check via commenting on this pull request:
 
 ```