Be sure check is usable even if flycheck-modules is deactivated

see #1804

elpy.el

@@ -572,6 +572,8 @@ virtualenv.
     (error "Please enable Elpy with `(elpy-enable)` before using it"))
   (when (boundp 'xref-backend-functions)
     (add-hook 'xref-backend-functions #'elpy--xref-backend nil t))
+  ;; Set this for `elpy-check' command
+  (setq-local python-check-command elpy-syntax-check-command)
   (cond
    (elpy-mode
     (elpy-modules-buffer-init))
@@ -3603,8 +3605,6 @@ If a region is selected, fold that region."
               elpy-folding-fringe-indicators)
          (setq-local flymake-fringe-indicator-position 'right-fringe)
        (setq-local flymake-fringe-indicator-position 'left-fringe))
-     ;; Set this for `elpy-check' command
-     (setq-local python-check-command elpy-syntax-check-command)
      ;; For emacs > 26.1, python.el natively supports flymake,
      ;; so we just tell python.el to use the wanted syntax checker
      (when (version<= "26.1" emacs-version)

test/elpy-mode-test.el

@@ -33,3 +33,13 @@
       (elpy-mode -1)
 
       (should buffer-stop-called))))
+
+
+(ert-deftest elpy-mode-should-set-python-check-command ()
+  (elpy-testcase ()
+    (mletf* ((executable-find (name) (equal name "flake8")))
+      (elpy-enable)
+      (python-mode)
+      (should (equal python-check-command "flake8"))
+      (if (version<= "26.1" emacs-version)
+          (should (equal python-flymake-command '("flake8" "-")))))))

test/elpy-module-flymake-test.el

@@ -1,12 +1,3 @@
-(ert-deftest elpy-module-flymake-global-init-should-use-flake8 ()
-  (elpy-testcase ()
-    (mletf* ((executable-find (name) (equal name "flake8")))
-      (elpy-module-flymake 'global-init)
-      (elpy-module-flymake 'buffer-init)
-      (should (equal python-check-command "flake8"))
-      (if (version<= "26.1" emacs-version)
-          (should (equal python-flymake-command '("flake8" "-")))))))
-
 (ert-deftest elpy-module-flymake-global-init ()
   (elpy-testcase ()
     (elpy-module-flymake 'global-init)