PLT-7111 Add groupmsg command (#7419)

* Coping command_msg to use as command_groupmsg base

* Changing msg to groupmsg names in groumsg command

* Add groupmsg command

app/command_groupmsg_test.go

@@ -0,0 +1,37 @@
+package app
+
+import (
+	"testing"
+)
+
+func TestGroupMsgUsernames(t *testing.T) {
+	if users, parsedMessage := groupMsgUsernames(""); len(users) != 0 || parsedMessage != "" {
+		t.Fatal("error parsing empty message")
+	}
+	if users, parsedMessage := groupMsgUsernames("test"); len(users) != 1 || parsedMessage != "" {
+		t.Fatal("error parsing simple user")
+	}
+	if users, parsedMessage := groupMsgUsernames("test1, test2, test3 , test4"); len(users) != 4 || parsedMessage != "" {
+		t.Fatal("error parsing various users")
+	}
+
+	if users, parsedMessage := groupMsgUsernames("test1, test2 message with spaces"); len(users) != 2 || parsedMessage != "message with spaces" {
+		t.Fatal("error parsing message")
+	}
+
+	if users, parsedMessage := groupMsgUsernames("test1, test2 message with, comma"); len(users) != 2 || parsedMessage != "message with, comma" {
+		t.Fatal("error parsing messages with comma")
+	}
+
+	if users, parsedMessage := groupMsgUsernames("test1,,,test2"); len(users) != 2 || parsedMessage != "" {
+		t.Fatal("error parsing multiple commas in username ")
+	}
+
+	if users, parsedMessage := groupMsgUsernames("    test1,       test2     other message         "); len(users) != 2 || parsedMessage != "other message" {
+		t.Fatal("error parsing strange usage of spaces")
+	}
+
+	if users, _ := groupMsgUsernames("    test1,       test2,,123,@321,+123"); len(users) != 5 || users[0] != "test1" || users[1] != "test2" || users[2] != "123" || users[3] != "321" || users[4] != "+123" {
+		t.Fatal("error parsing different types of users")
+	}
+}