test(font-config): smoke-cover the install check and daemon-frame applier

font-config.el had no direct tests. I added four: cj/font-installed-p returns t or nil depending on find-font, and cj/apply-font-settings-to-frame is a no-op on a non-GUI frame and applies the preset exactly once per frame, so reopening a daemon frame doesn't restack it.

find-font, env-gui-p, and fontaine-set-preset are stubbed so the run stays headless. The module :demand's fontaine and all-the-icons, so a skip-unless on those packages keeps a bare checkout green while the tests still run wherever the fonts are installed.

1 files changed, 74 insertions, 0 deletions

diff --git a/tests/test-font-config.el b/tests/test-font-config.el
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+++ b/tests/test-font-config.el
@@ -0,0 +1,74 @@
+;;; test-font-config.el --- Smoke tests for font-config -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;; font-config.el is mostly top-level font/package setup.  These smoke tests
+;; cover the logic that should stay correct regardless of which fonts are
+;; installed: the install check, and the daemon-frame font applier (env-gui-p
+;; guard plus idempotency).  The module :demand's fontaine and all-the-icons,
+;; so the tests skip when those packages are absent rather than failing on a
+;; bare checkout.  GUI and font lookups are stubbed so the run stays headless.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+
+;; font-config :demand's external packages, so make the installed packages
+;; reachable; the test runners do not package-initialize themselves.
+(package-initialize)
+
+(defconst test-font-config--available
+  (and (locate-library "fontaine")
+       (locate-library "all-the-icons")
+       (locate-library "all-the-icons-nerd-fonts"))
+  "Non-nil when the packages font-config :demand's are loadable.")
+
+;;; cj/font-installed-p
+
+(ert-deftest test-font-config-font-installed-p-true-when-found ()
+  "Normal: the install check returns t when the font is found."
+  (skip-unless test-font-config--available)
+  (require 'font-config)
+  (cl-letf (((symbol-function 'find-font) (lambda (&rest _) t)))
+    (should (eq t (cj/font-installed-p "BerkeleyMono Nerd Font")))))
+
+(ert-deftest test-font-config-font-installed-p-nil-when-absent ()
+  "Error: the install check returns nil when the font is missing."
+  (skip-unless test-font-config--available)
+  (require 'font-config)
+  (cl-letf (((symbol-function 'find-font) (lambda (&rest _) nil)))
+    (should (null (cj/font-installed-p "No Such Font 12345")))))
+
+;;; cj/apply-font-settings-to-frame
+
+(ert-deftest test-font-config-apply-font-settings-noop-without-gui ()
+  "Boundary: on a non-GUI frame the applier does nothing and does not error."
+  (skip-unless test-font-config--available)
+  (require 'font-config)
+  (let ((cj/fontaine-configured-frames nil)
+        (applied nil))
+    (cl-letf (((symbol-function 'env-gui-p) (lambda (&rest _) nil))
+              ((symbol-function 'fontaine-set-preset)
+               (lambda (&rest _) (setq applied t))))
+      (cj/apply-font-settings-to-frame (selected-frame))
+      (should-not applied)
+      (should-not cj/fontaine-configured-frames))))
+
+(ert-deftest test-font-config-apply-font-settings-applies-once-per-frame ()
+  "Normal: on a GUI frame the applier sets the preset once and is idempotent."
+  (skip-unless test-font-config--available)
+  (require 'font-config)
+  (let ((cj/fontaine-configured-frames nil)
+        (calls 0))
+    (cl-letf (((symbol-function 'env-gui-p) (lambda (&rest _) t))
+              ((symbol-function 'fontaine-set-preset)
+               (lambda (&rest _) (setq calls (1+ calls)))))
+      (cj/apply-font-settings-to-frame (selected-frame))
+      (cj/apply-font-settings-to-frame (selected-frame))
+      (should (= calls 1))
+      (should (memq (selected-frame) cj/fontaine-configured-frames)))))
+
+(provide 'test-font-config)
+;;; test-font-config.el ends here