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diff --git a/tests/test-system-utils--file-from-context.el b/tests/test-system-utils--file-from-context.el
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+;;; test-system-utils--file-from-context.el --- Tests for cj/--file-from-context -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Unit tests for `cj/--file-from-context' in system-utils.el.  The
+;; helper returns a file path from the current context, resolving in
+;; priority order: explicit argument, `buffer-file-name', dired file
+;; at point.  Returns nil when none of these yield a file.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'system-utils)
+
+(defmacro test-ffc--with-context (buffer-file in-dired dired-file &rest body)
+  "Run BODY with context stubbed for testing `cj/--file-from-context'.
+BUFFER-FILE becomes the value of `buffer-file-name'.
+IN-DIRED controls `derived-mode-p' (t to simulate dired-mode).
+DIRED-FILE becomes the return value of `dired-file-name-at-point'."
+  (declare (indent 3))
+  `(let ((buffer-file-name ,buffer-file))
+	 (cl-letf (((symbol-function 'derived-mode-p)
+				(lambda (&rest modes)
+				  (and ,in-dired (memq 'dired-mode modes))))
+			   ((symbol-function 'dired-file-name-at-point)
+				(lambda () ,dired-file)))
+	   ,@body)))
+
+;;; Normal cases
+
+(ert-deftest test-ffc-explicit-wins-over-buffer-file ()
+  "Normal: an explicit filename argument wins over `buffer-file-name'."
+  (test-ffc--with-context "/from-buffer.el" nil nil
+	(should (string= "/explicit.el"
+					 (cj/--file-from-context "/explicit.el")))))
+
+(ert-deftest test-ffc-explicit-wins-over-dired ()
+  "Normal: an explicit filename argument wins over dired file at point."
+  (test-ffc--with-context nil t "/from-dired.el"
+	(should (string= "/explicit.el"
+					 (cj/--file-from-context "/explicit.el")))))
+
+(ert-deftest test-ffc-buffer-file-used-when-no-explicit ()
+  "Normal: falls back to `buffer-file-name' when no explicit arg."
+  (test-ffc--with-context "/from-buffer.el" nil nil
+	(should (string= "/from-buffer.el"
+					 (cj/--file-from-context)))))
+
+(ert-deftest test-ffc-dired-used-when-no-explicit-no-buffer-file ()
+  "Normal: in a dired buffer, falls back to dired file at point."
+  (test-ffc--with-context nil t "/from-dired.el"
+	(should (string= "/from-dired.el"
+					 (cj/--file-from-context)))))
+
+;;; Boundary cases
+
+(ert-deftest test-ffc-all-sources-nil-returns-nil ()
+  "Boundary: no explicit, no buffer-file, not in dired → nil."
+  (test-ffc--with-context nil nil nil
+	(should-not (cj/--file-from-context))))
+
+(ert-deftest test-ffc-explicit-nil-uses-fallback-chain ()
+  "Boundary: explicitly passing nil as the arg still uses the fallback chain."
+  (test-ffc--with-context "/from-buffer.el" nil nil
+	(should (string= "/from-buffer.el"
+					 (cj/--file-from-context nil)))))
+
+(ert-deftest test-ffc-dired-mode-but-no-file-at-point ()
+  "Boundary: in dired but nothing at point returns nil (buffer-file also nil)."
+  (test-ffc--with-context nil t nil
+	(should-not (cj/--file-from-context))))
+
+(provide 'test-system-utils--file-from-context)
+;;; test-system-utils--file-from-context.el ends here