compile is part of CI

Makefile

@@ -1,16 +1,20 @@
 SHELL = /bin/sh
 EMACS ?= emacs
 PROFILER =
+EMACS_BATCH_OPTS=--batch -Q -l find-file-in-project.el
+RM = @rm -rf
 
-.PHONY: test
+.PHONY: test clean test compile
 
 # Delete byte-compiled files etc.
 clean:
-	rm -f *~
-	rm -f \#*\#
-	rm -f *.elc
+	$(RM) *~
+	$(RM) \#*\#
+	$(RM) *.elc
+
+compile: clean
+	@$(EMACS) $(EMACS_BATCH_OPTS) -l tests/my-byte-compile.el 2>&1 | grep -E "([Ee]rror|[Ww]arning):" && exit 1 || exit 0
 
 # Run tests.
-test: clean
-	! $(EMACS) -Q -batch -l find-file-in-project.el --eval "(byte-compile-file \"find-file-in-project.el\")" 2>&1 | grep "Warning: the function"
-	$(EMACS) -Q -batch -l ert -l find-file-in-project.el -l tests/ffip-tests.el
+test: compile
+	@$(EMACS) $(EMACS_BATCH_OPTS) -l tests/ffip-tests.el

tests/my-byte-compile.el

@@ -0,0 +1,43 @@
+;;; my-elint.el --- syntax check the code  -*- lexical-binding: t -*-
+
+;; Copyright (C) 2022 Chen Bin
+;;
+;; Author: Chen Bin <chenbin.sh@gmail.com>
+
+;; This file is NOT part of GNU Emacs.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;  Syntax check the code.  It's used in Emacs cli.
+;;
+
+;;; Code:
+
+(require 'find-lisp)
+
+(let ((files (find-lisp-find-files-internal
+              "."
+              (lambda (file dir)
+                (and (not (file-directory-p (expand-file-name file dir)))
+                     (string-match "\\.el$" file)
+                     (not (string-match "\\.dir-locals\\.el" file))))
+              (lambda (dir parent)
+                (not (or (member dir '("." ".." ".git" ".svn" "deps" "tests"))
+                         (file-symlink-p (expand-file-name dir parent))))))))
+  (dolist (file files)
+    (byte-compile-file file)))
+
+(provide 'my-byte-compile)
+;;; my-elint.el ends here