test(prog): cover formatter wiring for python, go, shell, typescript

Four test files plus a shared testutil that locks in the formatter
bindings on C-; f across the four languages. Each test file checks:

- the format command is fboundp after the relevant package loads
- the C-; f binding resolves to that command (in the relevant
  mode-map, or in the buffer-local map for hook-based wiring)
- the underlying executable is on PATH (skipped via ert-skip if
  not installed)

No production change. The bindings were already at C-; f via two
mechanisms. Use-package :bind handles python and shell. The other
two install via local-set-key inside a hook. This regression net
catches silent breakage if any of those wirings get reshaped later.

The shared tests/testutil-format-wiring.el carries
format-test--ensure-packages-init, which calls package-initialize
once per batch run, since make test runs Emacs with --no-site-file
--no-site-lisp. Without it, use-package can't find blacken / shfmt
/ go-mode in elpa/. Also format-test--skip-unless-executable wraps
ert-skip with a clear "not on PATH" message so missing tools fail
informatively.

Per-language wiring inventory (no changes, just locked in):
- Python: blacken-buffer in python-ts-mode-map (use-package :bind)
- Shell: shfmt-buffer in sh-mode-map and bash-ts-mode-map
  (use-package :bind, gated on :if executable-find)
- Go: gofmt via cj/go-mode-keybindings hook
- TS/JS/Web: cj/webdev-format-buffer via cj/webdev-keybindings hook

13 tests across 4 files, all passing.

1 files changed, 38 insertions, 0 deletions

diff --git a/tests/testutil-format-wiring.el b/tests/testutil-format-wiring.el
new file mode 100644
index 00000000..eba57564
--- /dev/null
+++ b/tests/testutil-format-wiring.el
@@ -0,0 +1,38 @@
+;;; testutil-format-wiring.el --- Shared helpers for formatter wiring tests -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Helpers used by the per-language formatter-wiring tests.  Two pieces:
+;;
+;; - `format-test--ensure-packages-init' bootstraps `package' once per
+;;   batch run so use-package forms in the prog-* modules can find
+;;   their packages in elpa.  The Makefile's test target invokes Emacs
+;;   with --no-site-file --no-site-lisp, which skips the implicit
+;;   `package-initialize' that an interactive session would do at
+;;   startup.
+;;
+;; - `format-test--skip-unless-executable' is a thin wrapper around
+;;   `ert-skip' for the "formatter not installed on this machine" path.
+;;   Tests that need the underlying binary on PATH call this first.
+
+;;; Code:
+
+(require 'ert)
+(require 'package)
+
+(defvar format-test--packages-initialized nil
+  "Non-nil once `package-initialize' has run in this batch process.")
+
+(defun format-test--ensure-packages-init ()
+  "Initialise `package' the first time this is called in a batch run."
+  (unless format-test--packages-initialized
+    (package-initialize)
+    (setq format-test--packages-initialized t)))
+
+(defun format-test--skip-unless-executable (program)
+  "Skip the current ERT test unless PROGRAM is on PATH."
+  (unless (executable-find program)
+    (ert-skip (format "%s not on PATH; skipping installation-dependent assertion"
+                      program))))
+
+(provide 'testutil-format-wiring)
+;;; testutil-format-wiring.el ends here