Fix defect with bot users when 'delete_previous_comments' is enabled

Indeed, in order to delete the correct comments, the golang code makes sure
that comment's `Author.Login` is the same as current `Viewer.Login`. But with
bot users, viewer's login is "githubApp[bot]" and author login is "githubApp".

As a consequence, for the comparison to succeed, we need to remove any
trailing "[bot]" suffix from both parties, and compare the resulting prefixes.

This isue was originally submitted as telia-oss#245 and
fixed later in monzo#4.

github.go

@@ -435,7 +435,7 @@ func (m *GithubClient) DeletePreviousComments(prNumber string) error {
 	}
 
 	for _, e := range getComments.Repository.PullRequest.Comments.Edges {
-		if e.Node.Author.Login == getComments.Viewer.Login {
+		if cleanBotUserName(e.Node.Author.Login) == cleanBotUserName(getComments.Viewer.Login) {
 			_, err := m.V3.Issues.DeleteComment(context.TODO(), m.Owner, m.Repository, e.Node.DatabaseId)
 			if err != nil {
 				return err
@@ -453,3 +453,10 @@ func parseRepository(s string) (string, string, error) {
 	}
 	return parts[0], parts[1], nil
 }
+
+func cleanBotUserName(username string) string {
+	if strings.HasSuffix(username, "[bot]") {
+		return strings.TrimSuffix(username, "[bot]")
+	}
+	return username
+}

github_test.go

@@ -25,3 +25,50 @@ func TestListTeamMembers(t *testing.T) {
 
 	require.Contains(t, val, "thelinuxfoundation")
 }
+
+func Test_cleanBotUserName(t *testing.T) {
+	type args struct {
+		username string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "Main Test Case",
+			args: args{
+				username: "infratest[bot]",
+			},
+			want: "infratest",
+		},
+		{
+			name: "Without suffix bot",
+			args: args{
+				username: "infratest",
+			},
+			want: "infratest",
+		},
+		{
+			name: "Bot only",
+			args: args{
+				username: "[bot]",
+			},
+			want: "",
+		},
+		{
+			name: "Bot at start",
+			args: args{
+				username: "[bot]infratest",
+			},
+			want: "[bot]infratest",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := cleanBotUserName(tt.args.username); got != tt.want {
+				t.Errorf("cleanBotUserName() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}