add constant test

src/main/scala/com/htmlism/mos6502/dsl/package.scala

@@ -34,6 +34,16 @@ package object dsl {
     definition
   }
 
+  def constant(name: String, x: Int)(implicit ctx: DefinitionGroupContext): Definition[Int] = {
+    val definition =
+      Definition(name, x)
+
+    ctx
+      .push(Definition(name, x))
+
+    definition
+  }
+
   implicit class AddressOps(n: Int) {
     def z: ZeroAddress =
       ZeroAddress(n)

src/test/scala/com/htmlism/mos6502/dsl/DslSpec.scala

@@ -26,6 +26,11 @@ class DslSpec extends AnyFlatSpec with should.Matchers {
             define("sysLastKey", 0xff.z))
         }
 
+        group("constants test") { implicit g =>
+          (constant("margin", 16),
+            constant("secret", 42))
+        }
+
         ()
       }
 
@@ -35,15 +40,22 @@ class DslSpec extends AnyFlatSpec with should.Matchers {
         Definition("snakeDirection", 0x02.z),
         Definition("snakeLength", 0x03.z)
       )),
+
       DefinitionGroup("ASCII values of keys controlling the snake", List(
         Definition("ASCII_w", 0x77.z),
         Definition("ASCII_a", 0x61.z),
         Definition("ASCII_s", 0x73.z),
         Definition("ASCII_d", 0x64.z)
       )),
+
       DefinitionGroup("System variables", List(
         Definition("sysRandom", 0xfe.z),
         Definition("sysLastKey", 0xff.z)
+      )),
+
+      DefinitionGroup("constants test", List(
+        Definition("margin", 16),
+        Definition("secret", 42)
       ))
     ))
   }