[widget audit] toga.Button

android/src/toga_android/widgets/button.py

@@ -25,9 +25,6 @@ def create(self):
         self.native.setOnClickListener(TogaOnClickListener(button_impl=self))
         self.cache_textview_defaults()
 
-    def get_text(self):
-        return str(self.native.getText())
-
     def set_text(self, text):
         self.native.setText(text)
 

cocoa/src/toga_cocoa/widgets/button.py

@@ -66,9 +66,6 @@ def set_font(self, font):
         # Button style is sensitive to font changes
         self._set_button_style()
 
-    def get_text(self):
-        return str(self.native.title)
-
     def set_text(self, text):
         self.native.title = text
 

core/src/toga/widgets/button.py

@@ -37,19 +37,26 @@ def __init__(
 
     @property
     def text(self):
-        """The text displayed on the button."""
-        return self._impl.get_text()
+        """The text displayed on the button.
+
+        ``None`` will be displayed as an empty string. Any other object will be converted
+        to a string using ``str()``.
+
+        Only one line of text can be displayed. Any content after the first newline will
+        be ignored.
+        """
+        return self._text
 
     @text.setter
     def text(self, value):
-        if not value:
-            raise ValueError("Button must have a label")
-
-        # Button text can't include line breaks. Strip any content
-        # after a line break (if provided)
-        value = str(value).split("\n")[0]
+        if value is None:
+            self._text = ""
+        else:
+            # Button text can't include line breaks. Strip any content
+            # after a line break (if provided)
+            self._text = str(value).split("\n")[0]
 
-        self._impl.set_text(value)
+        self._impl.set_text(self._text)
         self.refresh()
 
     @property

core/tests/widgets/test_button.py

@@ -3,10 +3,8 @@
 import toga
 from toga_dummy.utils import (
     EventLog,
-    assert_action_not_performed,
     assert_action_performed,
     assert_action_performed_with,
-    assert_attribute_not_set,
     attribute_value,
 )
 
@@ -27,6 +25,8 @@ def test_widget_created(button):
     "value, expected",
     [
         ("New Text", "New Text"),
+        ("", ""),
+        (None, ""),
         (12345, "12345"),
         ("Contains\nnewline", "Contains"),
     ],
@@ -48,30 +48,6 @@ def test_button_text(button, value, expected):
     assert_action_performed(button, "refresh")
 
 
-@pytest.mark.parametrize(
-    "value",
-    [
-        None,
-        "",
-    ],
-)
-def test_empty_button_text(button, value):
-    """The button label cannot be set to empty text."""
-    assert button.text == "Test Button"
-
-    # Clear the event log
-    EventLog.reset()
-
-    with pytest.raises(ValueError, match=r"Button must have a label"):
-        button.text = value
-
-    # test backend has not changed value
-    assert_attribute_not_set(button, "text")
-
-    # No refresh was performed
-    assert_action_not_performed(button, "refresh")
-
-
 def test_button_on_press(button):
     """The on_press handler can be invoked."""
     # No handler initially

docs/reference/api/widgets/button.rst

@@ -29,14 +29,8 @@ A button has a text label. A handler can be associated with button press events.
 
     button = toga.Button('Click me', on_press=my_callback)
 
-Notes
------
-* Any "truthy" object (i.e, object that evaluates as ``True``) can be provided
-  as the text for the button; if the object is not a string, it will be
-  automatically converted to a string using ``str()``.
-
-* The button text cannot contain newlines. Any content after the first newline
-  will be ignored.
+Styles
+------
 
 * A background color of ``TRANSPARENT`` will be treated as a reset of the button
   to the default system color.

docs/reference/api/widgets/label.rst

@@ -22,8 +22,8 @@ Usage
 
     label = toga.Label('Hello world')
 
-Notes
------
+Styles
+------
 
 * Winforms does not support an alignment value of ``JUSTIFIED``. If this
   alignment value is used, the label will default to left alignment.

dummy/src/toga_dummy/widgets/button.py

@@ -8,8 +8,5 @@ def create(self):
     def set_text(self, text):
         self._set_value("text", text)
 
-    def get_text(self):
-        return self._get_value("text")
-
     def set_on_press(self, handler):
         self._set_value("on_press", handler)

gtk/src/toga_gtk/widgets/button.py

@@ -16,9 +16,6 @@ def create(self):
         self.native.connect("show", lambda event: self.refresh())
         self.native.connect("clicked", self.gtk_on_press)
 
-    def get_text(self):
-        return self.native.get_label()
-
     def set_text(self, text):
         self.native.set_label(text)
 

iOS/src/toga_iOS/widgets/button.py

@@ -40,9 +40,6 @@ def create(self):
         # Add the layout constraints
         self.add_constraints()
 
-    def get_text(self):
-        return str(self.native.titleForState(UIControlStateNormal))
-
     def set_text(self, text):
         self.native.setTitle(text, forState=UIControlStateNormal)
 

testbed/tests/data.py

@@ -1,6 +1,6 @@
 from toga.colors import rgba
 
-TEXTS = [" ", "a", "ab", "abc", "hello world", "hello\nworld", "你好, wørłd!"]
+TEXTS = ["", " ", "a", "ab", "abc", "hello world", "hello\nworld", "你好, wørłd!"]
 
 
 COLORS = [

testbed/tests/widgets/properties.py

@@ -15,30 +15,6 @@ async def test_text(widget, probe):
         assert probe.text == text
 
 
-async def test_text_empty(widget, probe):
-    "The text displayed on a widget can be empty"
-    # Set the text to the empty string
-    widget.text = ""
-    await probe.redraw()
-
-    assert widget.text == ""
-    assert probe.text == ""
-
-    # Reset back to "actual" content
-    widget.text = "Hello"
-    await probe.redraw()
-
-    assert widget.text == "Hello"
-    assert probe.text == "Hello"
-
-    # Set the text to None; renders as an empty string
-    widget.text = None
-    await probe.redraw()
-
-    assert widget.text == ""
-    assert probe.text == ""
-
-
 async def test_text_width_change(widget, probe):
     "If the widget text is changed, the width of the widget changes"
     orig_width = probe.width

testbed/tests/widgets/test_button.py

@@ -33,8 +33,17 @@ async def test_text(widget, probe):
         await probe.redraw()
 
         # Text after a newline will be stripped.
-        assert widget.text == text.split("\n")[0]
-        assert probe.text == text.split("\n")[0]
+        expected = text.split("\n")[0]
+        assert widget.text == expected
+        try:
+            assert probe.text == expected
+        except AssertionError:
+            if probe.text == " " and expected == "":
+                # The Winforms backend avoids empty labels to prevent the widget height
+                # from collapsing.
+                pass
+            else:
+                raise
 
         assert probe.height == initial_height
 

testbed/tests/widgets/test_label.py

@@ -13,7 +13,6 @@
     test_font,
     test_font_attrs,
     test_text,
-    test_text_empty,
     test_text_width_change,
 )
 

web/src/toga_web/widgets/button.py

@@ -13,9 +13,6 @@ def dom_onclick(self, event):
         if self.interface.on_press:
             self.interface.on_press(self.interface)
 
-    def get_text(self):
-        return self.native.innerHTML
-
     def set_text(self, text):
         self.native.innerHTML = text
 

winforms/src/toga_winforms/widgets/button.py

@@ -16,10 +16,11 @@ def winforms_click(self, sender, event):
         if self.interface.on_press:
             self.interface.on_press(self.interface)
 
-    def get_text(self):
-        return self.native.Text
-
     def set_text(self, text):
+        if text == "":
+            # An empty label would cause the widget's height to collapse, so display a
+            # single space instead.
+            text = " "
         self.native.Text = text
 
     def set_font(self, font):