style and tools test fix

tests/test_style.py

@@ -114,6 +114,15 @@ def test_add():
     assert Style().__add__("foo") == NotImplemented
 
 
+def test_iadd():
+    style = Style(color="red")
+    style += Style(bold=True)
+    assert style == Style(color="red", bold=True)
+    style += None
+    assert style == Style(color="red", bold=True)
+    assert style.__iadd__("foo") == NotImplemented
+
+
 def test_style_stack():
     stack = StyleStack(Style(color="red"))
     repr(stack)

tests/test_tools.py

@@ -34,3 +34,4 @@ def test_ratio_divide():
     assert ratio_divide(12, [1, 3]) == [3, 9]
     assert ratio_divide(0, [1, 3]) == [0, 0]
     assert ratio_divide(0, [1, 3], [1, 1]) == [1, 1]
+    assert ratio_divide(10, [1, 0]) == [10, 0]