feat(wpcarro/emacs): Package al, list, set, struct

Originally I set-out to package `al.el`, but as I started traversing the
dependencies, I needed to package increasingly more packages. I refactored some
of these to prune their dependencies to slay this hydra before it turned into a
never-ending project. I have mixed feelings about this.

I also introduced `ert` and unit tests into my Elisp packaging, so it'll be nice
to have build-time tests that run when Emacs updates land in depot.

Change-Id: I2756dc60888b80255a495e08ae61bd547e6b3db2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5998
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

users/wpcarro/emacs/pkgs/al/tests.el

@@ -0,0 +1,34 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 'ert)
+(require 'al)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Tests
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(ert-deftest al-has-key? ()
+  (and
+   (al-has-key? 'fname '((fname . "William")))
+   (not (al-has-key? 'lname '((fname . "William"))))))
+
+(ert-deftest al-has-value? ()
+  (and
+   (al-has-value? "William" '((fname . "William")))
+   (not (al-has-key? "John" '((fname . "William"))))))
+
+(ert-deftest al-map-keys ()
+  (equal '((2 . one)
+           (3 . two))
+         (al-map-keys #'1+
+                      '((1 . one)
+                        (2 . two)))))
+
+(ert-deftest al-map-values ()
+  (equal '((one . 2)
+           (two . 3))
+         (al-map-values #'1+
+                        '((one . 1)
+                          (two . 2)))))