test(ai-config): cover gptel switch/add/toggle commands + small helpers

Second pass on ai-config. First batch covered the auth-source, API-key caching, file-context, clear-buffer, context-clear, and model-heading helpers. This batch covers the gptel command wrappers and a couple of small helpers:

- `cj/gptel--refresh-org-prefix`: refreshes the org-mode entry in `gptel-prompt-prefix-alist`.
- `cj/gptel-backend-and-model`: formats a vector-backend's name + the current model + a timestamp; falls back to "AI:" when no backend is bound.
- `cj/gptel-switch-backend`: picks a backend and one of its models, updates both gptel vars; errors on an invalid backend choice.
- `cj/gptel-add-buffer-file`: hands the visited file off to `cj/gptel--add-file-to-context`, messages otherwise.
- `cj/gptel-add-this-buffer`: calls `gptel-add` with the (4) prefix-arg.
- `cj/toggle-gptel`: deletes the window when *AI-Assistant* is already shown.

gptel and projectile primitives are stubbed throughout.

1 files changed, 152 insertions, 0 deletions

diff --git a/tests/test-ai-config-gptel-commands.el b/tests/test-ai-config-gptel-commands.el
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+;;; test-ai-config-gptel-commands.el --- Tests for ai-config gptel command wrappers -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Second pass on ai-config.  The first batch covered the helpers
+;; (auth-source, api-key caching, add-file, clear-buffer, context-
+;; clear, insert-model-heading).  This file covers the gptel command
+;; wrappers and a few small pure helpers:
+;;
+;;   cj/gptel--refresh-org-prefix
+;;   cj/gptel-backend-and-model
+;;   cj/gptel-switch-backend
+;;   cj/gptel-add-buffer-file
+;;   cj/gptel-add-this-buffer
+;;   cj/toggle-gptel
+;;
+;; The gptel/projectile primitives are stubbed throughout.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'ai-config)
+
+;; Dynamic vars gptel would normally own.
+(defvar gptel-backend nil)
+(defvar gptel-model nil)
+(defvar gptel-prompt-prefix-alist nil)
+
+;;; cj/gptel--refresh-org-prefix
+
+(ert-deftest test-ai-config-refresh-org-prefix-updates-alist-entry ()
+  "Normal: the advice refreshes the org-mode entry in the prefix alist."
+  (let ((gptel-prompt-prefix-alist '((org-mode . "stale\n"))))
+    (cj/gptel--refresh-org-prefix)
+    (let ((entry (alist-get 'org-mode gptel-prompt-prefix-alist)))
+      (should (stringp entry))
+      ;; Fresh prefix includes the user-login-name + a timestamp bracket.
+      (should (string-match-p "\\[" entry)))))
+
+;;; cj/gptel-backend-and-model
+
+(ert-deftest test-ai-config-backend-and-model-formats-with-vector-backend ()
+  "Normal: a vector backend's name element comes through formatted."
+  (let ((gptel-backend [unused-slot "Claude" other])
+        (gptel-model 'claude-opus-4-6))
+    (let ((s (cj/gptel-backend-and-model)))
+      (should (string-match-p "Claude" s))
+      (should (string-match-p "claude-opus-4-6" s)))))
+
+(ert-deftest test-ai-config-backend-and-model-falls-back-to-ai-when-no-backend ()
+  "Boundary: with no backend bound, the string starts with the AI fallback."
+  (let ((gptel-backend nil)
+        (gptel-model nil))
+    (should (string-prefix-p "AI:" (cj/gptel-backend-and-model)))))
+
+;;; cj/gptel-switch-backend
+
+(ert-deftest test-ai-config-switch-backend-sets-backend-and-model ()
+  "Normal: switch picks a backend + model, then updates the gptel vars."
+  (let ((gptel-backend nil)
+        (gptel-model nil)
+        (msg nil))
+    (cl-letf (((symbol-function 'cj/gptel--available-backends)
+               (lambda ()
+                 '(("Anthropic - Claude" . anthropic-backend))))
+              ((symbol-function 'gptel-backend-models)
+               (lambda (_b) '(claude-opus claude-sonnet)))
+              ((symbol-function 'completing-read)
+               (lambda (prompt collection &rest _)
+                 ;; First call -> backend choice; second -> model.
+                 (cond
+                  ((string-match-p "backend" prompt) "Anthropic - Claude")
+                  (t "claude-opus"))))
+              ((symbol-function 'message)
+               (lambda (fmt &rest args) (setq msg (apply #'format fmt args)))))
+      (cj/gptel-switch-backend))
+    (should (eq gptel-backend 'anthropic-backend))
+    (should (equal gptel-model "claude-opus"))
+    (should (string-match-p "Anthropic - Claude" msg))))
+
+(ert-deftest test-ai-config-switch-backend-error-invalid-choice ()
+  "Error: an unrecognized backend name signals user-error."
+  (cl-letf (((symbol-function 'cj/gptel--available-backends)
+             (lambda () '(("Anthropic - Claude" . backend-a))))
+            ((symbol-function 'completing-read)
+             (lambda (&rest _) "Something Else")))
+    (should-error (cj/gptel-switch-backend) :type 'user-error)))
+
+;;; cj/gptel-add-buffer-file
+
+(ert-deftest test-ai-config-add-buffer-file-adds-when-buffer-has-file ()
+  "Normal: a buffer that visits a file -> the file is added to context."
+  (let ((added nil))
+    (with-temp-buffer
+      (setq buffer-file-name "/tmp/sample.org")
+      (cl-letf (((symbol-function 'completing-read)
+                 (lambda (&rest _) (buffer-name)))
+                ((symbol-function 'cj/gptel--add-file-to-context)
+                 (lambda (f) (setq added f) t))
+                ((symbol-function 'message) #'ignore))
+        (cj/gptel-add-buffer-file))
+      (setq buffer-file-name nil))
+    (should (equal added "/tmp/sample.org"))))
+
+(ert-deftest test-ai-config-add-buffer-file-messages-when-no-file ()
+  "Boundary: a buffer not visiting a file -> message, no add call."
+  (let ((added nil)
+        (msg nil))
+    (with-temp-buffer
+      (cl-letf (((symbol-function 'completing-read)
+                 (lambda (&rest _) (buffer-name)))
+                ((symbol-function 'cj/gptel--add-file-to-context)
+                 (lambda (f) (setq added f) t))
+                ((symbol-function 'message)
+                 (lambda (fmt &rest args)
+                   (setq msg (apply #'format fmt args)))))
+        (cj/gptel-add-buffer-file)))
+    (should-not added)
+    (should (string-match-p "not visiting" msg))))
+
+;;; cj/gptel-add-this-buffer
+
+(ert-deftest test-ai-config-add-this-buffer-calls-gptel-add-with-prefix ()
+  "Normal: `cj/gptel-add-this-buffer' calls `gptel-add' with the (4) prefix arg."
+  (let ((arg nil))
+    (cl-letf (((symbol-function 'featurep) (lambda (_) t))
+              ((symbol-function 'gptel-add)
+               (lambda (a) (setq arg a)))
+              ((symbol-function 'message) #'ignore))
+      (with-temp-buffer
+        (cj/gptel-add-this-buffer)))
+    (should (equal arg '(4)))))
+
+;;; cj/toggle-gptel
+
+(ert-deftest test-ai-config-toggle-gptel-closes-when-window-shown ()
+  "Normal: with a window already displaying *AI-Assistant*, toggle deletes it."
+  (let* ((buf (generate-new-buffer "*AI-Assistant*"))
+         (deleted nil))
+    (unwind-protect
+        (cl-letf (((symbol-function 'get-buffer-window)
+                   (lambda (_b) 'fake-window))
+                  ((symbol-function 'delete-window)
+                   (lambda (w) (setq deleted w))))
+          (cj/toggle-gptel))
+      (when (buffer-live-p buf) (kill-buffer buf)))
+    (should (eq deleted 'fake-window))))
+
+(provide 'test-ai-config-gptel-commands)
+;;; test-ai-config-gptel-commands.el ends here