From 676610b43954b644c05823371df6daf87caafdad Mon Sep 17 00:00:00 2001
From: Sergei Lebedev <s.lebedev@criteo.com>
Date: Sun, 8 Apr 2018 20:11:13 +0200
Subject: [PATCH] Yet another fix of ``Screen.set_margins``

for the case of CSI with no arguments. See #61.
---
 CHANGES              | 4 ++++
 pyte/screens.py      | 3 ++-
 tests/test_screen.py | 9 +++++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index 2d452d3..6173b30 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,10 @@ Here you can see the full list of changes between each pyte release.
 Version 0.8.1-dev
 -----------------
 
+- Yet another fix of ``Screen.set_margins`` for the case of CSI
+  with no arguments. See issue #61 on GitHub.
+
+
 Version 0.8.0
 -------------
 
diff --git a/pyte/screens.py b/pyte/screens.py
index 648358f..e9adef0 100644
--- a/pyte/screens.py
+++ b/pyte/screens.py
@@ -331,7 +331,8 @@ def set_margins(self, top=None, bottom=None):
         :param int top: the smallest line number that is scrolled.
         :param int bottom: the biggest line number that is scrolled.
         """
-        if top is None and bottom is None:
+        # XXX 0 corresponds to the CSI with no parameters.
+        if (top is None or top == 0) and bottom is None:
             self.margins = None
             return
 
diff --git a/tests/test_screen.py b/tests/test_screen.py
index 6ff062a..5351c9e 100644
--- a/tests/test_screen.py
+++ b/tests/test_screen.py
@@ -1457,6 +1457,15 @@ def test_set_margins():
     assert screen.margins is None
 
 
+def test_set_margins_zero():
+    # See https://github.com/selectel/pyte/issues/61
+    screen = pyte.Screen(80, 24)
+    screen.set_margins(1, 5)
+    assert screen.margins == (0, 4)
+    screen.set_margins(0)
+    assert screen.margins is None
+
+
 def test_hide_cursor():
     screen = pyte.Screen(10, 10)