From da804769c659ac290fa00d34123ffe50101d38d3 Mon Sep 17 00:00:00 2001
From: Jairinho <t4ngz3r0@gmail.com>
Date: Wed, 23 Feb 2022 16:28:17 -0300
Subject: [PATCH] some checks to ensure stack consistency

---
 chip8/stack_test.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/chip8/stack_test.go b/chip8/stack_test.go
index f0fd33b..77313de 100644
--- a/chip8/stack_test.go
+++ b/chip8/stack_test.go
@@ -18,6 +18,17 @@ func TestEmulator_StackPush(t *testing.T) {
 	assert.Equal(t, chip8.StackAddress+2, emulator.SP)
 }
 
+func TestEmulator_StackPush_Overflow(t *testing.T) {
+	emulator := chip8.NewEmulator()
+
+	defer func() {
+		assert.Equal(t, "chip8: stack overflow", recover())
+	}()
+
+	emulator.SP = chip8.StackAddress + chip8.StackSize*2
+	emulator.StackPush()
+}
+
 func TestEmulator_StackPop(t *testing.T) {
 	emulator := chip8.NewEmulator()
 
@@ -29,3 +40,13 @@ func TestEmulator_StackPop(t *testing.T) {
 	assert.Equal(t, uint16(0xEEFF), emulator.PC)
 	assert.Equal(t, chip8.StackAddress+30, emulator.SP)
 }
+
+func TestEmulator_StackPop_Empty(t *testing.T) {
+	emulator := chip8.NewEmulator()
+
+	defer func() {
+		assert.Equal(t, "chip8: nothing to pop from stack", recover())
+	}()
+
+	emulator.StackPop()
+}