feat(tests): set up unit tests

Using FiveAM, and followed this tutorial:
https://turtleware.eu/posts/Tutorial-Working-with-FiveAM.html

homestead.asd

@@ -1,5 +1,22 @@
-(asdf:defsystem #:homestead
-  :serial t
-  :description "A static site generator"
-  :author "Gosha Tcherednitchenko"
-  :license "MIT")
+(defsystem "homestead"
+  :version "0.0.1"
+  :author "Gosha Tcherednitchenko <mail@gosha.net>"
+  :license "MIT License"
+  :depends-on (#:cl-markdown)
+  :components ((:module "src"
+                :components
+                ((:file "main"))))
+  :description "A static website generator"
+  :in-order-to ((test-op (test-op "homestead/tests"))))
+
+(defsystem "homestead/tests"
+  :author "Gosha Tcherednitchenko <mail@gosha.net>"
+  :license "MIT License"
+  :depends-on ("homestead"
+               "fiveam")
+  :components ((:module "tests"
+                :components
+                ((:file "main"))))
+  :description "Test system for homestead"
+  :perform (test-op (o s)
+            (uiop:symbol-call :fiveam :run! 'homestead/tests/main:all-tests)))

src/main.lisp

@@ -0,0 +1,5 @@
+(defpackage homestead
+  (:use :cl))
+(in-package :homestead)
+
+;; blah blah blah.

tests/main.lisp

@@ -0,0 +1,21 @@
+(defpackage homestead/tests/main
+  (:use :cl
+        :homestead
+        :fiveam)
+  (:export #:run! #:all-tests))
+(in-package #:homestead/tests/main)
+
+;; NOTE: To run this test file, execute `(asdf:test-system :homestead)' in your Lisp.
+
+(def-suite all-tests
+  :description "Global test suite")
+
+(in-suite all-tests)
+
+(defun test-homestead ()
+  (run! 'all-tests))
+
+(test dummy-tests
+  "Just a placeholder."
+  (is (listp (list 1 2)))
+  (is (= 5 (+ 2 3))))