Added stepping to debugger

tests.scm

@@ -144,4 +144,19 @@
     (stack-pop my-data)
     (stack-push my-data 1)
     (debugger-continue my-debugger)
-    (assert-equal 1 (vm-memory-ref my-vm 1))))
+    (assert-equal 1 (vm-memory-ref my-vm 1)))
+  (define-test "stepping"
+    (define my-debugger (make-debugger fib-program-asm))
+    (define my-vm (debugger-vm my-debugger))
+    (vm-memory-set! my-vm 1 10)
+    (vm-pc-set! my-vm 5)
+    (debugger-breakpoint-add! my-debugger 'fib)
+    (debugger-continue my-debugger)
+    (assert-equal 23 (vm-pc my-vm))
+    (debugger-step my-debugger)
+    (assert-equal 24 (vm-pc my-vm)) ;; dup is a 1 byte instruction
+    (debugger-step my-debugger)
+    (assert-equal 29 (vm-pc my-vm)) ;; push is a 5 byte instruction
+    (debugger-continue my-debugger)
+    (assert-equal 23 (vm-pc my-vm)) ;; continue stops stepping
+    ))