Merge pull request #1087 from davep/add-node-list-tests

Add unit tests for the NodeList class

tests/test_node_list.py

@@ -0,0 +1,72 @@
+from textual.widget import Widget
+from textual._node_list import NodeList
+
+def test_empty_list():
+    """Does an empty node list report as being empty?"""
+    assert len(NodeList())==0
+
+def test_add_one():
+    """Does adding a node to the node list report as having one item?"""
+    nodes = NodeList()
+    nodes._append(Widget())
+    assert len(nodes)==1
+
+def test_repeat_add_one():
+    """Does adding the same item to the node list ignore the additional adds?"""
+    nodes = NodeList()
+    widget = Widget()
+    for _ in range(1000):
+        nodes._append(widget)
+    assert len(nodes)==1
+
+def test_truthy():
+    """Does a node list act as a truthy object?"""
+    nodes = NodeList()
+    assert not bool(nodes)
+    nodes._append(Widget())
+    assert bool(nodes)
+
+def test_contains():
+    """Can we check if a widget is (not) within the list?"""
+    widget = Widget()
+    nodes = NodeList()
+    assert widget not in nodes
+    nodes._append(widget)
+    assert widget in nodes
+    assert Widget() not in nodes
+
+def test_remove():
+    """Can we remove a widget we've added?"""
+    widget = Widget()
+    nodes = NodeList()
+    nodes._append(widget)
+    assert widget in nodes
+    nodes._remove(widget)
+    assert widget not in nodes
+
+def test_clear():
+    """Can we clear the list?"""
+    nodes = NodeList()
+    assert len(nodes)==0
+    widgets = [Widget() for _ in range(1000)]
+    for widget in widgets:
+        nodes._append(widget)
+    assert len(nodes)==1000
+    for widget in widgets:
+        assert widget in nodes
+    nodes._clear()
+    assert len(nodes)==0
+    for widget in widgets:
+        assert widget not in nodes
+
+def test_listy():
+    nodes = NodeList()
+    widget1 = Widget()
+    widget2 = Widget()
+    nodes._append(widget1)
+    nodes._append(widget2)
+    assert list(nodes)==[widget1, widget2]
+    assert list(reversed(nodes))==[widget2, widget1]
+    assert nodes[0]==widget1
+    assert nodes[1]==widget2
+    assert nodes[0:2]==[widget1, widget2]