write unit tests for functions in utils package.

The tests are only for functions which do not require valide access tokens and
Id's for DNSimple or Telegram. I'm under the impression, the functions which
require valid access tokens and Id's will be better served by testing them
manually. I don't want to run the risk of including personal secret tokens with
the repositories commit history.

tests/tests.lisp

@@ -4,3 +4,92 @@
               #:parachute)
   (:documentation "Test suite for ddns-updater."))
 (in-package #:tests)
+
+(defparameter *application-root* (asdf:system-source-directory :ddns-updater))
+(defparameter *test-directory* (merge-pathnames "tests/" *application-root*))
+(defparameter *test-config-filename* "test-config.json")
+(defparameter *test-config-file-path*
+  (merge-pathnames *test-config-filename* *test-directory*))
+
+(define-test "Can make test configuration file."
+  (utils:make-config-file *test-config-file-path*)
+  (true (uiop:file-exists-p *test-config-file-path*)))
+
+(define-test "Back-Up file is created when configuration file already exists."
+  (utils:make-config-file *test-config-file-path*)
+  (is = 2 (count-if
+        (lambda (file) (search *test-config-filename* (namestring file)))
+        (uiop:directory-files *test-directory*))))
+
+(define-test "Configuration file matches expected schema."
+  (let ((data (utils:read-config-file *test-config-file-path*)))
+    (skip "Not ready yet.")))
+
+(define-test "Can add timestamp pre-fix to configuration filename."
+  ;; And example of what the timestamped string should look like:
+  ;; 20231217_14298_config.json If the date is the 2nd (for example) of the
+  ;; month, the the '0' is ommitted. So, 5th Feb. 2024 will look like '202425'
+  ;; instead of '20240205'.
+  (let ((regex "^\\d*_\\d*_")
+        (test-text (utils::add-filename-safe-timestamp *test-config-filename*)))
+    ;; '0' denotes start of matched string.`NIL' returned if no substring found.
+    (is = 0 (cl-ppcre:scan regex test-text))))
+
+(define-test "Can get IP address."
+  (let ((regex "^\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}$")
+        (test-text (utils::get-ip-address)))
+    ;; '0' denotes start of matched string.`NIL' returned if no substring found.
+    (is = 0 (cl-ppcre:scan regex test-text))))
+
+(define-test "Can update IP address in configuration file."
+  (let* ((conf-file (utils:read-config-file *test-config-file-path*))
+         (conf-old-ip (gethash "last-recorded-ip" conf-file))
+         (test-data-new-ip "192.168.1.1")) ; Use (utils::get-ip-address) typically.
+    (utils::update-conf-file-to-latest-ip
+     conf-file test-data-new-ip *test-config-file-path*)
+    (isnt string= conf-old-ip
+          (gethash "last-recorded-ip"
+                   (utils:read-config-file *test-config-file-path*)))))
+
+(define-test "Clean-up of test run is valid."
+  ;; This doesn't test the system, it just deletes temporary files used when
+  ;; running the unit tests. The test part is for verification.
+  (mapc
+   (lambda (file)
+     (when (search *test-config-filename* (namestring file))
+       (delete-file file)))
+   (uiop:directory-files *test-directory*))
+  (is = 0 (count-if
+        (lambda (file)
+          (search *test-config-filename* (namestring file)))
+        (uiop:directory-files *test-directory*))))
+
+#| Manual Testing Required
+================================================================================
+
+Unfortunately, there are some tests which cannot be ran without valid DNSimple
+and/or Telegram accounts. Because of this, the test suite cannot test all the
+functionality provided by this program, in an automated fashion.
+
+Once you have entered you valid DNSimple and/or Telegram account details in the
+config.json file, you can test the following functions below (in the utils
+package). The most likely way you'll do that is via SLIME/SLY in Emacs or via
+something like SBCL, using your CLI.
+
+Non-Exported (private) functions:
+
+- (get-accounts(conf-data path)
+- (get-domain-zones (conf-data path)
+- (get-records-in-zone (conf-data path)
+
+Exported (public) functions:
+
+- (send-notification (api-token chat-id message)
+- (update-ip-addresses (conf-data conf-path)
+
+The same applies to the CLI (binary) part of the program. You can't test it
+without valid DNSimple and/or Telegram accounts. Unfortunately, those details
+are specific to you and can't be included here (in a generalised, for everyone
+kinda way).
+
+|#