refactor(dirvish): extract cj/--dired-line-is-directory-p

`cj/dired-mark-all-visible-files' classified the current line as a directory via `(looking-at "^. d")' inline.  Lift the classification into `cj/--dired-line-is-directory-p', a string predicate that takes a line and returns non-nil when it's a directory listing.  The wrapper still walks the dired buffer line by line and calls `dired-mark' -- that iteration is dired-coupled and stays untested -- but the format-aware predicate is now isolated and verified.

Six Normal/Boundary tests cover unmarked directories, marked directories (`*' prefix), regular files (`-' instead of `d'), symlinks (`l'), empty lines, and dired header lines (`  /path:' and `  total N').

2 files changed, 71 insertions, 2 deletions

diff --git a/modules/dirvish-config.el b/modules/dirvish-config.el
index ad2227e8..f032b1a0 100644
--- a/modules/dirvish-config.el
+++ b/modules/dirvish-config.el
@@ -180,14 +180,27 @@ used by `cj/dirvish-open-html-in-eww'."
 
 ;;; ------------------------ Dired Mark All Visible Files -----------------------
 
+(defun cj/--dired-line-is-directory-p (line)
+  "Return non-nil when LINE is a Dired listing of a directory.
+
+Dired prefixes each file line with a one-character mark column followed
+by `ls -l' output, so a directory line reads as `<mark> drwx...' (mark,
+space, `d').  Header lines (`  /path/to:'), `total N' lines, and empty
+lines all fail this match.
+
+Pure helper used by `cj/dired-mark-all-visible-files'."
+  (and line (string-match-p "\\`. d" line)))
+
 (defun cj/dired-mark-all-visible-files ()
   "Mark all visible files in Dired mode."
   (interactive)
   (save-excursion
     (goto-char (point-min))
     (while (not (eobp))
-      (if (not (looking-at "^. d"))
-          (dired-mark 1))
+      (let ((line (buffer-substring-no-properties
+                   (line-beginning-position) (line-end-position))))
+        (unless (cj/--dired-line-is-directory-p line)
+          (dired-mark 1)))
       (forward-line 1))))
 
 ;;; ------------------------ Dirvish Duplicate File Copy ------------------------
diff --git a/tests/test-dirvish-config-dired-line-directory.el b/tests/test-dirvish-config-dired-line-directory.el
new file mode 100644
index 00000000..7f344c7c
--- /dev/null
+++ b/tests/test-dirvish-config-dired-line-directory.el
@@ -0,0 +1,56 @@
+;;; test-dirvish-config-dired-line-directory.el --- Tests for the directory-line predicate -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; `cj/--dired-line-is-directory-p' is the testable predicate behind
+;; `cj/dired-mark-all-visible-files'.  Dired buffers prefix each file
+;; line with a one-char mark column followed by the `ls -l' output, so
+;; column 2 is the file-type letter (`d' for directory, `-' for regular
+;; file).  The wrapper iterates the buffer and skips lines this
+;; predicate returns t for; the iteration stays dired-coupled and
+;; untested, but the line-classification logic is now isolated.
+
+;;; Code:
+
+(require 'ert)
+(require 'package)
+
+(setq package-user-dir (expand-file-name "elpa" user-emacs-directory))
+(package-initialize)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(add-to-list 'load-path (expand-file-name "elpa/dirvish-2.3.0/extensions"
+                                          user-emacs-directory))
+(require 'user-constants)
+(require 'keybindings)
+(require 'dirvish-config)
+
+(ert-deftest test-cj--dired-line-is-directory-p-unmarked-directory ()
+  "Normal: an unmarked directory line (`  drwx...') matches."
+  (should (cj/--dired-line-is-directory-p
+           "  drwxr-xr-x 1 me me 4096 May 10 13:00 subdir/")))
+
+(ert-deftest test-cj--dired-line-is-directory-p-marked-directory ()
+  "Normal: a star-marked directory line (`* drwx...') matches."
+  (should (cj/--dired-line-is-directory-p
+           "* drwxr-xr-x 1 me me 4096 May 10 13:00 subdir/")))
+
+(ert-deftest test-cj--dired-line-is-directory-p-regular-file ()
+  "Normal: a regular file line (`  -rw...') does not match."
+  (should-not (cj/--dired-line-is-directory-p
+               "  -rw-r--r-- 1 me me 42 May 10 13:00 notes.txt")))
+
+(ert-deftest test-cj--dired-line-is-directory-p-symlink-line ()
+  "Boundary: a symlink line (`  lrwx...') does not match -- only `d' is a dir."
+  (should-not (cj/--dired-line-is-directory-p
+               "  lrwxrwxrwx 1 me me 12 May 10 13:00 link -> target")))
+
+(ert-deftest test-cj--dired-line-is-directory-p-empty-line ()
+  "Boundary: an empty string does not match."
+  (should-not (cj/--dired-line-is-directory-p "")))
+
+(ert-deftest test-cj--dired-line-is-directory-p-header-line ()
+  "Boundary: a dired header (`  /path/to:') or `total' line does not match."
+  (should-not (cj/--dired-line-is-directory-p "  /home/me/projects:"))
+  (should-not (cj/--dired-line-is-directory-p "  total 24")))
+
+(provide 'test-dirvish-config-dired-line-directory)
+;;; test-dirvish-config-dired-line-directory.el ends here