From 6d637027e01f43623f4bca29c233cb7c298ebb08 Mon Sep 17 00:00:00 2001
From: Craig Jennings <c@cjennings.net>
Date: Sun, 10 May 2026 14:42:04 -0500
Subject: refactor(external-open): consolidate OS-open dispatch in
 external-open.el

Phase 4 of utility-consolidation. Three previously-overlapping helpers (system-utils' `cj/identify-external-open-command' and `cj/--open-with-is-launcher-p', plus the dirvish-only `cj/--file-manager-program-for' shipped earlier today) all answered "which OS-open program should I run?".  Pull the answer into one place: external-open.el.

Move and rename:

- `cj/--open-with-is-launcher-p' (system-utils) -> `cj/external-open-launcher-p' (external-open). Public name now matches its module.
- `cj/identify-external-open-command' (system-utils) -> `cj/external-open-command' (external-open). Returns nil for unsupported hosts instead of signaling -- callers that need a command must handle nil explicitly. The wrapper `cj/xdg-open' (also moved into external-open) converts nil to a `user-error' with a clear message, preserving the user-facing failure shape.
- Delete dirvish's `cj/--file-manager-program-for' helper. `cj/dirvish-open-file-manager-here' now calls `cj/external-open-command' directly. The shell-command fallback for nil-program preserves the previous escape hatch.

Break the system-utils <-> external-open recursive require by moving `cj/xdg-open' (the only system-utils function that external-open used) into external-open along with the dispatch.

Tests reorganized to match the move. Two new test files (`test-external-open-command.el', `test-external-open-launcher-p.el') replace the two system-utils-named test files. The dirvish file-manager-program test goes away with the helper. 11 tests covering Normal/Boundary/Error for the dispatch (plus the new "unsupported host returns nil" contract).

Add `(require \='external-open)' to system-utils.el and `(require \='system-lib)' to external-open.el (for `cj/file-from-context' which xdg-open uses).
---
 .../test-system-utils--open-with-is-launcher-p.el  | 52 ----------------------
 1 file changed, 52 deletions(-)
 delete mode 100644 tests/test-system-utils--open-with-is-launcher-p.el

(limited to 'tests/test-system-utils--open-with-is-launcher-p.el')

diff --git a/tests/test-system-utils--open-with-is-launcher-p.el b/tests/test-system-utils--open-with-is-launcher-p.el
deleted file mode 100644
index 64e9a4b6..00000000
--- a/tests/test-system-utils--open-with-is-launcher-p.el
+++ /dev/null
@@ -1,52 +0,0 @@
-;;; test-system-utils--open-with-is-launcher-p.el --- Tests for cj/--open-with-is-launcher-p -*- lexical-binding: t; -*-
-
-;;; Commentary:
-;; Unit tests for `cj/--open-with-is-launcher-p' in system-utils.el.
-;; The predicate returns t for desktop launcher commands (xdg-open,
-;; open, start) that need `call-process' with a zero buffer argument
-;; to fully detach from Emacs.  Anything else returns nil.
-
-;;; Code:
-
-(require 'ert)
-
-(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
-(require 'system-utils)
-
-;;; Normal cases
-
-(ert-deftest test-owilp-xdg-open-is-launcher ()
-  "Normal: \"xdg-open\" (Linux launcher) returns t."
-  (should (eq t (cj/--open-with-is-launcher-p "xdg-open"))))
-
-(ert-deftest test-owilp-open-is-launcher ()
-  "Normal: \"open\" (macOS launcher) returns t."
-  (should (eq t (cj/--open-with-is-launcher-p "open"))))
-
-(ert-deftest test-owilp-start-is-launcher ()
-  "Normal: \"start\" (Windows launcher) returns t."
-  (should (eq t (cj/--open-with-is-launcher-p "start"))))
-
-;;; Boundary cases
-
-(ert-deftest test-owilp-non-launcher-command-returns-nil ()
-  "Boundary: a non-launcher command (e.g. gimp) returns nil."
-  (should-not (cj/--open-with-is-launcher-p "gimp")))
-
-(ert-deftest test-owilp-empty-string-returns-nil ()
-  "Boundary: empty string is not a launcher."
-  (should-not (cj/--open-with-is-launcher-p "")))
-
-(ert-deftest test-owilp-case-sensitive ()
-  "Boundary: launcher check is case-sensitive (\"Open\" is not \"open\")."
-  (should-not (cj/--open-with-is-launcher-p "Open"))
-  (should-not (cj/--open-with-is-launcher-p "XDG-OPEN")))
-
-;;; Error cases
-
-(ert-deftest test-owilp-nil-argument-returns-nil ()
-  "Error: nil input is handled gracefully (not in the launcher list)."
-  (should-not (cj/--open-with-is-launcher-p nil)))
-
-(provide 'test-system-utils--open-with-is-launcher-p)
-;;; test-system-utils--open-with-is-launcher-p.el ends here
-- 
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