Add unit tests to cover bitplane 0 edge cases.

test/test_chip8screen.py

@@ -44,6 +44,14 @@ def test_all_pixels_off_on_screen_init(self):
                 self.assertEqual(0, self.screen.get_pixel(x_pos, y_pos, 1))
                 self.assertEqual(0, self.screen.get_pixel(x_pos, y_pos, 2))
 
+    def test_get_pixel_on_bitplane_0_returns_false(self):
+        self.screen.init_display()
+        for xpos in range(64):
+            for ypos in range(32):
+                self.screen.draw_pixel(xpos, ypos, 1, 1)
+                self.screen.draw_pixel(xpos, ypos, 1, 2)
+                self.assertFalse(self.screen.get_pixel(xpos, ypos, 0))
+
     def test_write_pixel_turns_on_pixel_on_bitplane(self):
         self.screen.init_display()
         for xpos in range(64):
@@ -60,6 +68,14 @@ def test_write_pixel_turns_on_pixel_on_both_bitplanes(self):
                 self.assertTrue(self.screen.get_pixel(xpos, ypos, 1))
                 self.assertTrue(self.screen.get_pixel(xpos, ypos, 2))
 
+    def test_write_pixel_does_nothing_on_bitplane_0(self):
+        self.screen.init_display()
+        for xpos in range(64):
+            for ypos in range(32):
+                self.screen.draw_pixel(xpos, ypos, 1, 0)
+                self.assertFalse(self.screen.get_pixel(xpos, ypos, 1))
+                self.assertFalse(self.screen.get_pixel(xpos, ypos, 2))
+
     def test_clear_screen_clears_pixels_on_bitplane_1(self):
         self.screen.init_display()
         for x_pos in range(64):
@@ -83,6 +99,30 @@ def test_clear_screen_clears_pixels_on_bitplane_1_only_when_both_set(self):
                 self.assertFalse(self.screen.get_pixel(x_pos, y_pos, 1))
                 self.assertTrue(self.screen.get_pixel(x_pos, y_pos, 2))
 
+    def test_clear_screen_on_bitplane_0_does_nothing(self):
+        self.screen.init_display()
+        for xpos in range(64):
+            for ypos in range(32):
+                self.screen.draw_pixel(xpos, ypos, 1, 1)
+                self.screen.draw_pixel(xpos, ypos, 1, 2)
+        self.screen.clear_screen(0)
+        for xpos in range(64):
+            for ypos in range(32):
+                self.assertTrue(self.screen.get_pixel(xpos, ypos, 1))
+                self.assertTrue(self.screen.get_pixel(xpos, ypos, 2))
+
+    def test_scroll_down_bitplane_0_does_nothing(self):
+        self.screen.init_display()
+        self.screen.draw_pixel(0, 0, 1, 1)
+        self.screen.draw_pixel(0, 0, 1, 2)
+        self.assertTrue(self.screen.get_pixel(0, 0, 1))
+        self.assertTrue(self.screen.get_pixel(0, 0, 2))
+        self.screen.scroll_down(1, 0)
+        self.assertTrue(self.screen.get_pixel(0, 0, 1))
+        self.assertTrue(self.screen.get_pixel(0, 0, 2))
+        self.assertFalse(self.screen.get_pixel(0, 1, 1))
+        self.assertFalse(self.screen.get_pixel(0, 1, 2))
+
     def test_scroll_down_bitplane_1(self):
         self.screen.init_display()
         self.screen.draw_pixel(0, 0, 1, 1)
@@ -118,6 +158,24 @@ def test_scroll_down_bitplane_3_both_pixels_active(self):
         self.assertTrue(self.screen.get_pixel(0, 1, 1))
         self.assertTrue(self.screen.get_pixel(0, 1, 2))
 
+    def test_scroll_right_bitplane_0_does_nothing(self):
+        self.screen.init_display()
+        self.screen.draw_pixel(0, 0, 1, 1)
+        self.screen.draw_pixel(0, 0, 1, 2)
+        self.assertTrue(self.screen.get_pixel(0, 0, 1))
+        self.assertTrue(self.screen.get_pixel(0, 0, 2))
+        self.screen.scroll_right(0)
+        self.assertTrue(self.screen.get_pixel(0, 0, 1))
+        self.assertFalse(self.screen.get_pixel(1, 0, 1))
+        self.assertFalse(self.screen.get_pixel(2, 0, 1))
+        self.assertFalse(self.screen.get_pixel(3, 0, 1))
+        self.assertFalse(self.screen.get_pixel(4, 0, 1))
+        self.assertTrue(self.screen.get_pixel(0, 0, 2))
+        self.assertFalse(self.screen.get_pixel(1, 0, 2))
+        self.assertFalse(self.screen.get_pixel(2, 0, 2))
+        self.assertFalse(self.screen.get_pixel(3, 0, 2))
+        self.assertFalse(self.screen.get_pixel(4, 0, 2))
+
     def test_scroll_right_bitplane_1(self):
         self.screen.init_display()
         self.screen.draw_pixel(0, 0, 1, 1)
@@ -171,6 +229,24 @@ def test_scroll_right_bitplane_3_both_pixels_active(self):
         self.assertFalse(self.screen.get_pixel(3, 0, 2))
         self.assertTrue(self.screen.get_pixel(4, 0, 2))
 
+    def test_scroll_left_bitplane_0_does_nothing(self):
+        self.screen.init_display()
+        self.screen.draw_pixel(63, 0, 1, 1)
+        self.screen.draw_pixel(63, 0, 1, 2)
+        self.assertTrue(self.screen.get_pixel(63, 0, 1))
+        self.assertTrue(self.screen.get_pixel(63, 0, 2))
+        self.screen.scroll_left(0)
+        self.assertTrue(self.screen.get_pixel(63, 0, 1))
+        self.assertFalse(self.screen.get_pixel(62, 0, 1))
+        self.assertFalse(self.screen.get_pixel(61, 0, 1))
+        self.assertFalse(self.screen.get_pixel(60, 0, 1))
+        self.assertFalse(self.screen.get_pixel(59, 0, 1))
+        self.assertTrue(self.screen.get_pixel(63, 0, 2))
+        self.assertFalse(self.screen.get_pixel(62, 0, 2))
+        self.assertFalse(self.screen.get_pixel(61, 0, 2))
+        self.assertFalse(self.screen.get_pixel(60, 0, 2))
+        self.assertFalse(self.screen.get_pixel(59, 0, 2))
+
     def test_scroll_left_bitplane_1(self):
         self.screen.init_display()
         self.screen.draw_pixel(63, 0, 1, 1)