refactor(transcription): extract cj/--build-process-environment

Pull the per-backend env-var assembly out of cj/--start-transcription-process
into a standalone pure function. 9 tests cover: the three backends, parent-env
preservation, non-mutation, missing-key user-error, unknown-backend error.

1 files changed, 94 insertions, 0 deletions

diff --git a/tests/test-transcription-process-environment.el b/tests/test-transcription-process-environment.el
new file mode 100644
index 00000000..95f26e13
--- /dev/null
+++ b/tests/test-transcription-process-environment.el
@@ -0,0 +1,94 @@
+;;; test-transcription-process-environment.el --- Tests for env-var assembly -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for `cj/--build-process-environment', which returns a
+;; `process-environment'-compatible list augmented with the API-key env
+;; var for the active backend (or unchanged for local backends).
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(defvar cj/custom-keymap (make-sparse-keymap))
+
+(unless (fboundp 'notifications-notify)
+  (defun notifications-notify (&rest _args) nil))
+
+(require 'transcription-config)
+
+(defmacro test-env-with-api-key (key-value &rest body)
+  "Run BODY with `cj/--auth-source-password' returning KEY-VALUE."
+  (declare (indent 1))
+  `(cl-letf (((symbol-function 'cj/--auth-source-password)
+              (lambda (&rest _) ,key-value)))
+     ,@body))
+
+;;; Normal Cases
+
+(ert-deftest test-build-env-normal-openai-prepends-key-var ()
+  "openai-api backend prepends OPENAI_API_KEY=<key>."
+  (test-env-with-api-key "sk-abc"
+    (let ((process-environment '("PATH=/usr/bin")))
+      (let ((result (cj/--build-process-environment 'openai-api)))
+        (should (equal "OPENAI_API_KEY=sk-abc" (car result)))
+        (should (member "PATH=/usr/bin" result))))))
+
+(ert-deftest test-build-env-normal-assemblyai-prepends-key-var ()
+  "assemblyai backend prepends ASSEMBLYAI_API_KEY=<key>."
+  (test-env-with-api-key "aai-xyz"
+    (let ((process-environment '("PATH=/usr/bin")))
+      (let ((result (cj/--build-process-environment 'assemblyai)))
+        (should (equal "ASSEMBLYAI_API_KEY=aai-xyz" (car result)))
+        (should (member "PATH=/usr/bin" result))))))
+
+(ert-deftest test-build-env-normal-local-whisper-unchanged ()
+  "local-whisper has no API key; environment is returned unchanged."
+  (let ((process-environment '("PATH=/usr/bin" "HOME=/tmp")))
+    (let ((result (cj/--build-process-environment 'local-whisper)))
+      (should (equal '("PATH=/usr/bin" "HOME=/tmp") result)))))
+
+(ert-deftest test-build-env-normal-preserves-parent-environment ()
+  "Every entry in the parent `process-environment' remains present."
+  (test-env-with-api-key "k"
+    (let ((process-environment '("A=1" "B=2" "C=3")))
+      (let ((result (cj/--build-process-environment 'openai-api)))
+        (should (member "A=1" result))
+        (should (member "B=2" result))
+        (should (member "C=3" result))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-build-env-boundary-empty-parent-env ()
+  "Empty parent `process-environment' yields a list with just the API-key var."
+  (test-env-with-api-key "k"
+    (let ((process-environment '()))
+      (let ((result (cj/--build-process-environment 'openai-api)))
+        (should (equal '("OPENAI_API_KEY=k") result))))))
+
+(ert-deftest test-build-env-boundary-does-not-mutate-input ()
+  "Parent `process-environment' is not destructively modified."
+  (test-env-with-api-key "k"
+    (let* ((parent '("PATH=/usr/bin"))
+           (process-environment parent))
+      (cj/--build-process-environment 'openai-api)
+      (should (equal '("PATH=/usr/bin") parent)))))
+
+;;; Error Cases
+
+(ert-deftest test-build-env-error-openai-missing-key ()
+  "openai-api with no key configured signals user-error."
+  (test-env-with-api-key nil
+    (should-error (cj/--build-process-environment 'openai-api) :type 'user-error)))
+
+(ert-deftest test-build-env-error-assemblyai-missing-key ()
+  "assemblyai with no key configured signals user-error."
+  (test-env-with-api-key nil
+    (should-error (cj/--build-process-environment 'assemblyai) :type 'user-error)))
+
+(ert-deftest test-build-env-error-unknown-backend ()
+  "Unknown backend bubbles up user-error from cj/--backend-plist."
+  (should-error (cj/--build-process-environment 'nonexistent) :type 'user-error))
+
+(provide 'test-transcription-process-environment)
+;;; test-transcription-process-environment.el ends here