From bb522f4f68b601942502bc70cb68eb24325eeb24 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 09:13:34 +0800
Subject: [PATCH 01/21] Update tests for label.

---
 testbed/tests/widgets/properties.py  | 40 +++++++++++++++++++++++++++
 testbed/tests/widgets/test_button.py | 41 +---------------------------
 testbed/tests/widgets/test_label.py  | 26 ++++++++----------
 3 files changed, 53 insertions(+), 54 deletions(-)

diff --git a/testbed/tests/widgets/properties.py b/testbed/tests/widgets/properties.py
index b9603ce65b..05b693e2bf 100644
--- a/testbed/tests/widgets/properties.py
+++ b/testbed/tests/widgets/properties.py
@@ -1,5 +1,6 @@
 from toga.colors import RED, TRANSPARENT, color as named_color
 from toga.fonts import FANTASY
+from toga.style.pack import COLUMN
 
 from ..assertions import assert_color
 from ..data import COLORS, TEXTS
@@ -143,3 +144,42 @@ async def test_background_color_transparent(widget, probe):
     widget.style.background_color = TRANSPARENT
     await probe.redraw()
     assert_color(probe.background_color, TRANSPARENT)
+
+
+async def test_flex_horizontal_widget_size(widget, probe):
+    "Check that a widget that is flexible in the horizontal axis resizes as expected"
+    # Container is initially a non-flex row box.
+    # Initial widget size is small (but non-zero), based on content size.
+    await probe.redraw()
+    assert 10 <= probe.width <= 150, f"Width ({probe.width}) not in range (10, 150)"
+    assert 10 <= probe.height <= 50, f"Height ({probe.height}) not in range (10, 50)"
+
+    # Make the widget flexible; it will expand to fill horizontal space
+    widget.style.flex = 1
+
+    # widget has expanded width, but has the same height.
+    await probe.redraw()
+    assert probe.width > 350
+    assert probe.height <= 50
+
+    # Make the container a flexible column box
+    # This will make the height the flexible axis
+    widget.parent.style.direction = COLUMN
+
+    # Widget is still the width of the screen
+    # and the height hasn't changed
+    await probe.redraw()
+    assert probe.width > 350
+    assert probe.height <= 50
+
+    # Set an explicit height and width
+    widget.style.width = 300
+    widget.style.height = 200
+
+    # Widget is approximately the requested size
+    # (Definitely less than the window size)
+    await probe.redraw()
+    assert 290 <= probe.width <= 330, f"Width ({probe.width}) not in range (290, 330)"
+    assert (
+        190 <= probe.height <= 230
+    ), f"Height ({probe.height}) not in range (190, 230)"
diff --git a/testbed/tests/widgets/test_button.py b/testbed/tests/widgets/test_button.py
index 16e81fd61b..8d69db4bbb 100644
--- a/testbed/tests/widgets/test_button.py
+++ b/testbed/tests/widgets/test_button.py
@@ -4,7 +4,6 @@
 
 import toga
 from toga.colors import TRANSPARENT
-from toga.style.pack import COLUMN
 
 from ..assertions import assert_color
 from ..data import TEXTS
@@ -13,6 +12,7 @@
     test_background_color_reset,
     test_color,
     test_color_reset,
+    test_flex_horizontal_widget_size,
     test_font,
     test_text_width_change,
 )
@@ -55,42 +55,3 @@ async def test_background_color_transparent(widget, probe):
     widget.style.background_color = TRANSPARENT
     await probe.redraw()
     assert_color(probe.background_color, None)
-
-
-async def test_button_size(widget, probe):
-    "Check that the button resizes"
-    # Container is initially a non-flex row box.
-    # Initial button size is small (but non-zero), based on content size.
-    await probe.redraw()
-    assert 10 <= probe.width <= 150, f"Width ({probe.width}) not in range (10, 150)"
-    assert 10 <= probe.height <= 50, f"Height ({probe.height}) not in range (10, 50)"
-
-    # Make the button flexible; it will expand to fill horizontal space
-    widget.style.flex = 1
-
-    # Button has expanded width, but has the same height.
-    await probe.redraw()
-    assert probe.width > 350
-    assert probe.height <= 50
-
-    # Make the container a flexible column box
-    # This will make the height the flexible axis
-    widget.parent.style.direction = COLUMN
-
-    # Button is still the width of the screen
-    # and the height hasn't changed
-    await probe.redraw()
-    assert probe.width > 350
-    assert probe.height <= 50
-
-    # Set an explicit height and width
-    widget.style.width = 300
-    widget.style.height = 200
-
-    # Button is approximately the requested size
-    # (Definitely less than the window size)
-    await probe.redraw()
-    assert 290 <= probe.width <= 330, f"Width ({probe.width}) not in range (290, 330)"
-    assert (
-        190 <= probe.height <= 230
-    ), f"Height ({probe.height}) not in range (190, 230)"
diff --git a/testbed/tests/widgets/test_label.py b/testbed/tests/widgets/test_label.py
index 2120ae4c5b..2432452d7a 100644
--- a/testbed/tests/widgets/test_label.py
+++ b/testbed/tests/widgets/test_label.py
@@ -1,7 +1,6 @@
-from pytest import approx, fixture, mark
+from pytest import approx, fixture
 
 import toga
-from toga.platform import current_platform
 from toga.style.pack import CENTER, COLUMN, JUSTIFY, LEFT, LTR, RIGHT, RTL
 
 from .properties import (  # noqa: F401
@@ -10,6 +9,7 @@
     test_background_color_transparent,
     test_color,
     test_color_reset,
+    test_flex_horizontal_widget_size,
     test_font,
     test_text,
     test_text_empty,
@@ -19,32 +19,29 @@
 
 @fixture
 async def widget():
-    return toga.Label("hello")
+    return toga.Label("hello, this is a label")
 
 
-test_text_width_change = mark.skipif(
-    current_platform in {"linux"},
-    reason="resizes not applying correctly",
-)(test_text_width_change)
-
-
-# TODO: a `width` test, for any widget whose width depends on its text.
-@mark.skip("changing text does not trigger a refresh (#1289)")
 async def test_multiline(widget, probe):
+    """If the label contains multiline text, it resizes"""
+
     def make_lines(n):
         return "\n".join(f"line{i}" for i in range(n))
 
     widget.text = make_lines(1)
-    # TODO: Android at least will need an `await` after each text change, to give the
-    # native layout a chance to update.
+
+    await probe.redraw()
     line_height = probe.height
 
     widget.text = make_lines(2)
+
+    await probe.redraw()
     assert probe.height == approx(line_height * 2, rel=0.1)
     line_spacing = probe.height - (line_height * 2)
 
     for n in range(3, 10):
         widget.text = make_lines(n)
+        await probe.redraw()
         assert probe.height == approx(
             (line_height * n) + (line_spacing * (n - 1)),
             rel=0.1,
@@ -52,6 +49,7 @@ def make_lines(n):
 
 
 async def test_alignment(widget, probe):
+    """Labels honor alignment settings"""
     # Initial alignment is LEFT, initial direction is LTR
     widget.parent.style.direction = COLUMN
     await probe.redraw()
@@ -63,7 +61,7 @@ async def test_alignment(widget, probe):
         probe.assert_alignment_equivalent(probe.alignment, alignment)
 
     # Clearing the alignment reverts to default alignment of LEFT
-    widget.style.text_align = None
+    del widget.style.text_align
     await probe.redraw()
     assert probe.alignment == LEFT
 

From 7ff85486c3cb08311f72bb083d2f16dc387b4ad4 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 09:14:45 +0800
Subject: [PATCH 02/21] Add Android text alignment probe, and support for text
 justification.

---
 android/src/toga_android/libs/android/graphics.py |  2 ++
 android/src/toga_android/libs/android/os.py       |  3 +++
 android/src/toga_android/widgets/label.py         | 15 +++++++++++----
 android/tests_backend/widgets/label.py            |  7 ++++---
 android/tests_backend/widgets/properties.py       | 13 +++++++++++++
 5 files changed, 33 insertions(+), 7 deletions(-)
 create mode 100644 android/src/toga_android/libs/android/os.py

diff --git a/android/src/toga_android/libs/android/graphics.py b/android/src/toga_android/libs/android/graphics.py
index 4b99c4b034..b7be31cc7e 100644
--- a/android/src/toga_android/libs/android/graphics.py
+++ b/android/src/toga_android/libs/android/graphics.py
@@ -13,3 +13,5 @@
 PorterDuffColorFilter = JavaClass("android/graphics/PorterDuffColorFilter")
 Rect = JavaClass("android/graphics/Rect")
 Typeface = JavaClass("android/graphics/Typeface")
+
+LineBreaker = JavaClass("android/graphics/text/LineBreaker")
diff --git a/android/src/toga_android/libs/android/os.py b/android/src/toga_android/libs/android/os.py
new file mode 100644
index 0000000000..25f4a762b5
--- /dev/null
+++ b/android/src/toga_android/libs/android/os.py
@@ -0,0 +1,3 @@
+from rubicon.java import JavaClass
+
+Build = JavaClass("android/os/Build")
diff --git a/android/src/toga_android/widgets/label.py b/android/src/toga_android/widgets/label.py
index bc687c61c6..d3f5e0d81f 100644
--- a/android/src/toga_android/widgets/label.py
+++ b/android/src/toga_android/widgets/label.py
@@ -1,7 +1,10 @@
 from travertino.size import at_least
 
+from toga.constants import JUSTIFY
 from toga_android.colors import native_color
 
+from ..libs.android.graphics import LineBreaker
+from ..libs.android.os import Build
 from ..libs.android.view import Gravity, View__MeasureSpec
 from ..libs.android.widget import TextView
 from .base import Widget, align
@@ -50,12 +53,16 @@ def rehint(self):
         self.interface.intrinsic.width = at_least(self.native.getMeasuredWidth())
 
     def set_alignment(self, value):
-        # Refuse to set alignment if create() has not been called.
-        if self.native is None:
-            return
         # Refuse to set alignment if widget has no container.
         # On Android, calling setGravity() when the widget has no LayoutParams
         # results in a NullPointerException.
         if not self.native.getLayoutParams():
             return
-        self.native.setGravity(Gravity.CENTER_VERTICAL | align(value))
+
+        # Justified text wasn't added until Android O (SDK 26)
+        if value == JUSTIFY and Build.VERSION.SDK_INT >= Build.VERSION_CODES.O:
+            self.native.setJustificationMode(LineBreaker.JUSTIFICATION_MODE_INTER_WORD)
+            self.native.setGravity(Gravity.CENTER_VERTICAL)
+        else:
+            self.native.setJustificationMode(LineBreaker.JUSTIFICATION_MODE_NONE)
+            self.native.setGravity(Gravity.CENTER_VERTICAL | align(value))
diff --git a/android/tests_backend/widgets/label.py b/android/tests_backend/widgets/label.py
index ef31e56954..1598da5c77 100644
--- a/android/tests_backend/widgets/label.py
+++ b/android/tests_backend/widgets/label.py
@@ -1,8 +1,7 @@
 from java import jclass
-from pytest import skip
 
 from .base import SimpleProbe
-from .properties import toga_color, toga_font
+from .properties import toga_alignment, toga_color, toga_font
 
 
 class LabelProbe(SimpleProbe):
@@ -30,4 +29,6 @@ def font(self):
 
     @property
     def alignment(self):
-        skip("Alignment probe not implemented")
+        return toga_alignment(
+            self.native.getGravity(), self.native.getJustificationMode()
+        )
diff --git a/android/tests_backend/widgets/properties.py b/android/tests_backend/widgets/properties.py
index 33042ada27..38990f4aa9 100644
--- a/android/tests_backend/widgets/properties.py
+++ b/android/tests_backend/widgets/properties.py
@@ -2,8 +2,11 @@
 from travertino.fonts import Font
 
 from android.graphics import Color, Typeface
+from android.graphics.text import LineBreaker
 from android.util import TypedValue
+from android.view import Gravity
 from toga.colors import TRANSPARENT, rgba
+from toga.constants import CENTER, JUSTIFY, LEFT, RIGHT
 from toga.fonts import (
     BOLD,
     ITALIC,
@@ -57,3 +60,13 @@ def toga_font(typeface, size, resources):
         variant=NORMAL,
         weight=BOLD if typeface.isBold() else NORMAL,
     )
+
+
+def toga_alignment(alignment, justification_mode):
+    if justification_mode == LineBreaker.JUSTIFICATION_MODE_INTER_WORD:
+        return JUSTIFY
+    return {
+        Gravity.LEFT: LEFT,
+        Gravity.RIGHT: RIGHT,
+        Gravity.CENTER_HORIZONTAL: CENTER,
+    }[alignment & Gravity.HORIZONTAL_GRAVITY_MASK]

From 4363a9899bab405035409443d382ec7096d857f8 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 09:58:26 +0800
Subject: [PATCH 03/21] Correct label implementation on iOS.

---
 iOS/src/toga_iOS/colors.py         |  3 ++-
 iOS/src/toga_iOS/widgets/button.py |  1 -
 iOS/src/toga_iOS/widgets/label.py  | 13 +++++++------
 iOS/tests_backend/widgets/label.py |  6 +++---
 4 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/iOS/src/toga_iOS/colors.py b/iOS/src/toga_iOS/colors.py
index 7bf636d4d1..25d80f3360 100644
--- a/iOS/src/toga_iOS/colors.py
+++ b/iOS/src/toga_iOS/colors.py
@@ -1,6 +1,7 @@
+from toga.colors import TRANSPARENT
 from toga_iOS.libs import UIColor
 
-CACHE = {}
+CACHE = {TRANSPARENT: UIColor.clearColor}
 
 
 def native_color(c):
diff --git a/iOS/src/toga_iOS/widgets/button.py b/iOS/src/toga_iOS/widgets/button.py
index 7d88840819..9f4cfb896e 100644
--- a/iOS/src/toga_iOS/widgets/button.py
+++ b/iOS/src/toga_iOS/widgets/button.py
@@ -61,7 +61,6 @@ def set_color(self, color):
             )
 
     def set_background_color(self, color):
-        # By default, background color can't be changed
         if color == TRANSPARENT or color is None:
             self.native.backgroundColor = None
         else:
diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index 31703255d5..eb20a964c4 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -10,21 +10,21 @@
 class Label(Widget):
     def create(self):
         self.native = UILabel.new()
+        # Word wrap the text inside the allocated space
         self.native.lineBreakMode = NSLineBreakByWordWrapping
 
         # Add the layout constraints
         self.add_constraints()
 
     def set_alignment(self, value):
-        if value:
-            self.native.textAlignment = NSTextAlignment(value)
+        self.native.textAlignment = NSTextAlignment(value)
 
     def set_color(self, value):
         self.native.textColor = native_color(value)
 
     def set_background_color(self, color):
-        if color is TRANSPARENT:
-            self.native.backgroundColor = None
+        if color == TRANSPARENT or color is None:
+            self.native.backgroundColor = native_color(TRANSPARENT)
         else:
             self.native.backgroundColor = native_color(color)
 
@@ -33,10 +33,11 @@ def set_font(self, font):
 
     def set_text(self, value):
         self.native.text = self.interface.text
+        # Tell the text layout algorithm how many lines are allowed
+        self.native.numberOfLines = len(self.interface.text.split("\n"))
 
     def rehint(self):
-        # Width & height of a label is known and fixed.
-        # print("REHINT label", self, self.native.fittingSize().width, self.native.fittingSize().height)
         fitting_size = self.native.systemLayoutSizeFittingSize(CGSize(0, 0))
+        # print("REHINT label", self, fitting_size.width, fitting_size.height)
         self.interface.intrinsic.width = at_least(fitting_size.width)
         self.interface.intrinsic.height = fitting_size.height
diff --git a/iOS/tests_backend/widgets/label.py b/iOS/tests_backend/widgets/label.py
index 51e1702576..2614e80f84 100644
--- a/iOS/tests_backend/widgets/label.py
+++ b/iOS/tests_backend/widgets/label.py
@@ -1,5 +1,5 @@
-from toga.color import TRANSPARENT
-from toga_iOS.libs import UILabel
+from toga.colors import TRANSPARENT
+from toga_iOS.libs import UIColor, UILabel
 
 from .base import SimpleProbe
 from .properties import toga_alignment, toga_color, toga_font
@@ -18,7 +18,7 @@ def color(self):
 
     @property
     def background_color(self):
-        if self.native.backgroundColor is None:
+        if self.native.backgroundColor == UIColor.clearColor:
             return TRANSPARENT
         else:
             return toga_color(self.native.backgroundColor)

From af06298fe9cf2cc7f7e397a0cd018052c0b33d6f Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:25:21 +0800
Subject: [PATCH 04/21] Migrate label tests to pytest.

---
 core/src/toga/widgets/label.py        | 15 +-------
 core/tests/test_deprecated_factory.py |  6 ---
 core/tests/widgets/test_label.py      | 54 ++++++++++++++++++---------
 3 files changed, 37 insertions(+), 38 deletions(-)

diff --git a/core/src/toga/widgets/label.py b/core/src/toga/widgets/label.py
index 1b038472dc..c44141f53f 100644
--- a/core/src/toga/widgets/label.py
+++ b/core/src/toga/widgets/label.py
@@ -1,5 +1,3 @@
-import warnings
-
 from .base import Widget
 
 
@@ -9,7 +7,6 @@ def __init__(
         text,
         id=None,
         style=None,
-        factory=None,  # DEPRECATED!
     ):
         """A text label.
 
@@ -19,20 +16,9 @@ def __init__(
         :param id: The ID for the widget.
         :param style: A style object. If no style is provided, a default style
             will be applied to the widget.
-        :param factory: *Deprecated*
         """
         super().__init__(id=id, style=style)
 
-        ######################################################################
-        # 2022-09: Backwards compatibility
-        ######################################################################
-        # factory no longer used
-        if factory:
-            warnings.warn("The factory argument is no longer used.", DeprecationWarning)
-        ######################################################################
-        # End backwards compatibility.
-        ######################################################################
-
         # Create a platform specific implementation of a Label
         self._impl = self.factory.Label(interface=self)
 
@@ -49,5 +35,6 @@ def text(self, value):
             self._text = ""
         else:
             self._text = str(value)
+
         self._impl.set_text(value)
         self.refresh()
diff --git a/core/tests/test_deprecated_factory.py b/core/tests/test_deprecated_factory.py
index 514f018a6c..16422502fa 100644
--- a/core/tests/test_deprecated_factory.py
+++ b/core/tests/test_deprecated_factory.py
@@ -118,12 +118,6 @@ def test_image_view_created(self):
         self.assertEqual(widget._impl.interface, widget)
         self.assertNotEqual(widget.factory, self.factory)
 
-    def test_label_created(self):
-        with self.assertWarns(DeprecationWarning):
-            widget = toga.Label("Test", factory=self.factory)
-        self.assertEqual(widget._impl.interface, widget)
-        self.assertNotEqual(widget.factory, self.factory)
-
     def test_multiline_text_input_created(self):
         with self.assertWarns(DeprecationWarning):
             widget = toga.MultilineTextInput(factory=self.factory)
diff --git a/core/tests/widgets/test_label.py b/core/tests/widgets/test_label.py
index a6fd7404cc..3f04a4e16c 100644
--- a/core/tests/widgets/test_label.py
+++ b/core/tests/widgets/test_label.py
@@ -1,27 +1,45 @@
+import pytest
+
 import toga
-from toga_dummy.utils import TestCase
+from toga_dummy.utils import (
+    EventLog,
+    assert_action_performed,
+    attribute_value,
+)
+
+
+@pytest.fixture
+def label():
+    return toga.Label("Test Label")
 
 
-class LabelTests(TestCase):
-    def setUp(self):
-        super().setUp()
+def test_label_created(label):
+    "A label can be created."
+    # Round trip the impl/interface
+    assert label._impl.interface == label
+    assert_action_performed(label, "create Label")
 
-        self.text = "test text"
 
-        self.label = toga.Label(self.text)
+@pytest.mark.parametrize(
+    "value, expected",
+    [
+        ("New Text", "New Text"),
+        (12345, "12345"),
+        (None, ""),
+        ("Contains\nsome\nnewlines", "Contains\nsome\nnewlines"),
+    ],
+)
+def test_update_label_text(label, value, expected):
+    assert label.text == "Test Label"
 
-    def test_widget_created(self):
-        self.assertEqual(self.label._impl.interface, self.label)
-        self.assertActionPerformed(self.label, "create Label")
+    # Clear the event log
+    EventLog.reset()
 
-    def test_update_label_text(self):
-        new_text = "updated text"
-        self.label.text = new_text
-        self.assertEqual(self.label.text, new_text)
-        self.assertValueSet(self.label, "text", new_text)
-        self.assertActionPerformed(self.label, "refresh")
+    label.text = value
+    assert label.text == expected
 
-        self.label.text = None
-        self.assertEqual(self.label.text, "")
+    # test backend has the right value
+    assert attribute_value(label, "text") == expected
 
-        self.assertValueSet(self.label, "text", "")
+    # A rehint was performed
+    assert_action_performed(label, "refresh")

From 71b523cfaf03dfc9fc4a7a83728b60d5b8e32fa8 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:32:24 +0800
Subject: [PATCH 05/21] Update documentation for Label.

---
 docs/reference/api/widgets/button.rst | 2 +-
 docs/reference/api/widgets/label.rst  | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/docs/reference/api/widgets/button.rst b/docs/reference/api/widgets/button.rst
index c6ad5e28c3..b443d2ffd3 100644
--- a/docs/reference/api/widgets/button.rst
+++ b/docs/reference/api/widgets/button.rst
@@ -27,7 +27,7 @@ A button has a text label. A handler can be associated with button press events.
         # handle event
         pass
 
-    button = toga.Button('Click me', on_press=my_callback)
+    button = toga.Button("Click me", on_press=my_callback)
 
 Notes
 -----
diff --git a/docs/reference/api/widgets/label.rst b/docs/reference/api/widgets/label.rst
index 5ee8be3440..779c48aec6 100644
--- a/docs/reference/api/widgets/label.rst
+++ b/docs/reference/api/widgets/label.rst
@@ -20,13 +20,17 @@ Usage
 
     import toga
 
-    label = toga.Label('Hello world')
+    label = toga.Label("Hello world")
 
 Notes
 -----
 
+* Any object can be provided as the text for the label. If the object is
+  ``None``, this will be converted into the empty string; any other non-string
+  object will be automatically converted to a string using ``str()``.
+
 * Winforms does not support an alignment value of ``JUSTIFIED``. If this
-  alignment value is used, the label will default left alignment.
+  alignment value is used, the label will default to left alignment.
 
 Reference
 ---------

From 35f3f6c055eaf5951f50dead03a12097963c3c22 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:32:40 +0800
Subject: [PATCH 06/21] Add changenote for label bugfix.

---
 changes/1289.bugfix.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changes/1289.bugfix.rst

diff --git a/changes/1289.bugfix.rst b/changes/1289.bugfix.rst
new file mode 100644
index 0000000000..ae5e074a6a
--- /dev/null
+++ b/changes/1289.bugfix.rst
@@ -0,0 +1 @@
+Label widgets now correctly resize after a change in label text.

From 0a833509d5560100ec48abc5d6d7a1cf262528e9 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:35:23 +0800
Subject: [PATCH 07/21] Add changenote for Label audit.

---
 changes/1799.feature.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changes/1799.feature.rst

diff --git a/changes/1799.feature.rst b/changes/1799.feature.rst
new file mode 100644
index 0000000000..9747d91a74
--- /dev/null
+++ b/changes/1799.feature.rst
@@ -0,0 +1 @@
+The Label widget now has 100% test coverage, and complete API documentation.

From 4238cb61cee0ff68b4eb32fc3165b3f9c06dc8d1 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:55:39 +0800
Subject: [PATCH 08/21] Add GTK alignment probe.

---
 gtk/src/toga_gtk/widgets/button.py      |  1 -
 gtk/src/toga_gtk/widgets/label.py       |  7 +------
 gtk/tests_backend/widgets/label.py      |  9 ++++++---
 gtk/tests_backend/widgets/properties.py | 21 ++++++++++++++-------
 4 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/gtk/src/toga_gtk/widgets/button.py b/gtk/src/toga_gtk/widgets/button.py
index 7571ad3879..557d84536a 100644
--- a/gtk/src/toga_gtk/widgets/button.py
+++ b/gtk/src/toga_gtk/widgets/button.py
@@ -13,7 +13,6 @@ def create(self):
         self.native.get_style_context().add_class("toga")
         self.native.interface = self.interface
 
-        self.native.connect("show", lambda event: self.refresh())
         self.native.connect("clicked", self.gtk_on_press)
 
     def get_text(self):
diff --git a/gtk/src/toga_gtk/widgets/label.py b/gtk/src/toga_gtk/widgets/label.py
index f4fb69a614..aa1c04357c 100644
--- a/gtk/src/toga_gtk/widgets/label.py
+++ b/gtk/src/toga_gtk/widgets/label.py
@@ -9,12 +9,9 @@ def create(self):
         self.native = Gtk.Label()
         self.native.set_name(f"toga-{self.interface.id}")
         self.native.get_style_context().add_class("toga")
-
-        self.native.set_line_wrap(False)
-
         self.native.interface = self.interface
 
-        self.native.connect("show", lambda event: self.refresh())
+        self.native.set_line_wrap(False)
 
     def set_alignment(self, value):
         xalign, justify = gtk_alignment(value)
@@ -25,8 +22,6 @@ def set_alignment(self, value):
         )  # Aligns multiple lines relative to each other.
 
     def set_text(self, value):
-        # FIXME after setting the label the label jumps to the top left
-        # corner and only jumps back at its place after resizing the window.
         self.native.set_text(self.interface._text)
 
     def rehint(self):
diff --git a/gtk/tests_backend/widgets/label.py b/gtk/tests_backend/widgets/label.py
index 0f4df67dcd..5965ef3705 100644
--- a/gtk/tests_backend/widgets/label.py
+++ b/gtk/tests_backend/widgets/label.py
@@ -1,8 +1,7 @@
-from pytest import skip
-
 from toga_gtk.libs import Gtk
 
 from .base import SimpleProbe
+from .properties import toga_alignment
 
 
 class LabelProbe(SimpleProbe):
@@ -14,4 +13,8 @@ def text(self):
 
     @property
     def alignment(self):
-        skip("alignment probe not implemented")
+        return toga_alignment(
+            self.native.get_xalign(),
+            self.native.get_yalign(),
+            self.native.get_justify(),
+        )
diff --git a/gtk/tests_backend/widgets/properties.py b/gtk/tests_backend/widgets/properties.py
index bc0ed1ef40..b51ac31756 100644
--- a/gtk/tests_backend/widgets/properties.py
+++ b/gtk/tests_backend/widgets/properties.py
@@ -1,3 +1,4 @@
+import pytest
 from travertino.fonts import Font
 
 from toga.colors import TRANSPARENT, rgba
@@ -30,10 +31,16 @@ def toga_font(font):
     )
 
 
-def toga_alignment(alignment):
-    return {
-        (0.0, Gtk.Justification.LEFT): LEFT,
-        (1.0, Gtk.Justification.RIGHT): RIGHT,
-        (0.5, Gtk.Justification.CENTER): CENTER,
-        (0.0, Gtk.Justification.FILL): JUSTIFY,
-    }[alignment]
+def toga_alignment(xalign, yalign, justify):
+    if yalign != 0.5:
+        pytest.fail("Y-alignment should be 0.5")
+
+    try:
+        return {
+            (0.0, Gtk.Justification.LEFT): LEFT,
+            (1.0, Gtk.Justification.RIGHT): RIGHT,
+            (0.5, Gtk.Justification.CENTER): CENTER,
+            (0.0, Gtk.Justification.FILL): JUSTIFY,
+        }[(xalign, justify)]
+    except KeyError:
+        pytest.fail(f"Can't interpret GTK x alignment {xalign} with justify {justify}")

From d0b3da089552091f17979290160443ed28c5cd18 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 1 Mar 2023 10:57:25 +0800
Subject: [PATCH 09/21] Update widget support chart.

---
 docs/reference/data/widgets_by_platform.csv | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/reference/data/widgets_by_platform.csv b/docs/reference/data/widgets_by_platform.csv
index d0987ffc59..677cb6e794 100644
--- a/docs/reference/data/widgets_by_platform.csv
+++ b/docs/reference/data/widgets_by_platform.csv
@@ -9,7 +9,7 @@ DatePicker,General Widget,:class:`~toga.widgets.datepicker.DatePicker`,An input
 DetailedList,General Widget,:class:`~toga.widgets.detailedlist.DetailedList`,A list of complex content,|b|,|b|,,|b|,|b|,
 Divider,General Widget,:class:`~toga.widgets.divider.Divider`,A horizontal or vertical line,|b|,|b|,|b|,,,
 ImageView,General Widget,:class:`~toga.widgets.imageview.ImageView`,Image Viewer,|b|,|b|,|b|,|b|,|b|,
-Label,General Widget,:class:`~toga.widgets.label.Label`,Text label,|b|,|b|,|b|,|b|,|b|,|b|
+Label,General Widget,:class:`~toga.widgets.label.Label`,Text label,|y|,|y|,|y|,|y|,|y|,|b|
 MultilineTextInput,General Widget,:class:`~toga.widgets.multilinetextinput.MultilineTextInput`,Multi-line Text Input field,|b|,|b|,|b|,|b|,|b|,
 NumberInput,General Widget,:class:`~toga.widgets.numberinput.NumberInput`,Number Input field,|b|,|b|,|b|,|b|,|b|,
 PasswordInput,General Widget,:class:`~toga.widgets.passwordinput.PasswordInput`,A text input that hides it’s input,|b|,|b|,|b|,|b|,|b|,

From 4691de80c2408b0068254b0dd3fc9cfc99815634 Mon Sep 17 00:00:00 2001
From: Malcolm Smith <smith@chaquo.com>
Date: Tue, 21 Mar 2023 17:47:23 +0000
Subject: [PATCH 10/21] Tighten up Android alignment tests

---
 android/src/toga_android/widgets/label.py   |  3 +--
 android/tests_backend/widgets/base.py       |  4 ++--
 android/tests_backend/widgets/properties.py | 21 ++++++++++++++-------
 cocoa/tests_backend/widgets/base.py         |  4 ++--
 gtk/tests_backend/widgets/base.py           |  4 ++--
 iOS/tests_backend/widgets/base.py           |  4 ++--
 testbed/tests/widgets/test_label.py         | 10 +++++-----
 winforms/tests_backend/widgets/base.py      |  3 ++-
 8 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/android/src/toga_android/widgets/label.py b/android/src/toga_android/widgets/label.py
index 67e6293917..ff70b35de6 100644
--- a/android/src/toga_android/widgets/label.py
+++ b/android/src/toga_android/widgets/label.py
@@ -66,7 +66,6 @@ def set_alignment(self, value):
         # Justified text wasn't added until Android O (SDK 26)
         if value == JUSTIFY and Build.VERSION.SDK_INT >= Build.VERSION_CODES.O:
             self.native.setJustificationMode(LineBreaker.JUSTIFICATION_MODE_INTER_WORD)
-            self.native.setGravity(Gravity.CENTER_VERTICAL)
         else:
             self.native.setJustificationMode(LineBreaker.JUSTIFICATION_MODE_NONE)
-            self.native.setGravity(Gravity.CENTER_VERTICAL | align(value))
+        self.native.setGravity(Gravity.CENTER_VERTICAL | align(value))
diff --git a/android/tests_backend/widgets/base.py b/android/tests_backend/widgets/base.py
index 64a7cd17b2..8a6c5dd0f1 100644
--- a/android/tests_backend/widgets/base.py
+++ b/android/tests_backend/widgets/base.py
@@ -48,8 +48,8 @@ def assert_container(self, container):
         else:
             raise AssertionError(f"cannot find {self.native} in {container_native}")
 
-    def assert_alignment_equivalent(self, actual, expected):
-        assert actual == expected
+    def assert_alignment(self, expected):
+        assert self.alignment == expected
 
     def assert_font_family(self, expected):
         actual = self.font.family
diff --git a/android/tests_backend/widgets/properties.py b/android/tests_backend/widgets/properties.py
index bb0af66e8b..ae497c3fab 100644
--- a/android/tests_backend/widgets/properties.py
+++ b/android/tests_backend/widgets/properties.py
@@ -67,11 +67,18 @@ def toga_font(typeface, size, resources):
     )
 
 
-def toga_alignment(alignment, justification_mode):
-    if justification_mode == LineBreaker.JUSTIFICATION_MODE_INTER_WORD:
+def toga_alignment(gravity, justification_mode):
+    horizontal_gravity = gravity & Gravity.HORIZONTAL_GRAVITY_MASK
+    if (
+        justification_mode == LineBreaker.JUSTIFICATION_MODE_INTER_WORD
+        and horizontal_gravity == Gravity.LEFT
+    ):
         return JUSTIFY
-    return {
-        Gravity.LEFT: LEFT,
-        Gravity.RIGHT: RIGHT,
-        Gravity.CENTER_HORIZONTAL: CENTER,
-    }[alignment & Gravity.HORIZONTAL_GRAVITY_MASK]
+    elif justification_mode == LineBreaker.JUSTIFICATION_MODE_NONE:
+        return {
+            Gravity.LEFT: LEFT,
+            Gravity.RIGHT: RIGHT,
+            Gravity.CENTER_HORIZONTAL: CENTER,
+        }[horizontal_gravity]
+    else:
+        raise ValueError(f"unknown combination: {gravity=}, {justification_mode=}")
diff --git a/cocoa/tests_backend/widgets/base.py b/cocoa/tests_backend/widgets/base.py
index b1a83c4462..bad58265cf 100644
--- a/cocoa/tests_backend/widgets/base.py
+++ b/cocoa/tests_backend/widgets/base.py
@@ -17,8 +17,8 @@ def assert_container(self, container):
         else:
             raise ValueError(f"cannot find {self.native} in {container_native}")
 
-    def assert_alignment_equivalent(self, actual, expected):
-        assert actual == expected
+    def assert_alignment(self, expected):
+        assert self.alignment == expected
 
     def assert_font_family(self, expected):
         assert self.font.family == {
diff --git a/gtk/tests_backend/widgets/base.py b/gtk/tests_backend/widgets/base.py
index 9fdaad89c6..d0fee7ffc4 100644
--- a/gtk/tests_backend/widgets/base.py
+++ b/gtk/tests_backend/widgets/base.py
@@ -26,8 +26,8 @@ def assert_container(self, container):
         else:
             raise ValueError(f"cannot find {self.native} in {container_native}")
 
-    def assert_alignment_equivalent(self, actual, expected):
-        assert actual == expected
+    def assert_alignment(self, expected):
+        assert self.alignment == expected
 
     def assert_font_family(self, expected):
         assert self.font.family == expected
diff --git a/iOS/tests_backend/widgets/base.py b/iOS/tests_backend/widgets/base.py
index 3f1afabca3..db2ce267a1 100644
--- a/iOS/tests_backend/widgets/base.py
+++ b/iOS/tests_backend/widgets/base.py
@@ -45,8 +45,8 @@ def assert_container(self, container):
         else:
             raise ValueError(f"cannot find {self.native} in {container_native}")
 
-    def assert_alignment_equivalent(self, actual, expected):
-        assert actual == expected
+    def assert_alignment(self, expected):
+        assert self.alignment == expected
 
     def assert_font_family(self, expected):
         assert self.font.family == {
diff --git a/testbed/tests/widgets/test_label.py b/testbed/tests/widgets/test_label.py
index 621ebc6789..d08790aca6 100644
--- a/testbed/tests/widgets/test_label.py
+++ b/testbed/tests/widgets/test_label.py
@@ -53,24 +53,24 @@ async def test_alignment(widget, probe):
     # Initial alignment is LEFT, initial direction is LTR
     widget.parent.style.direction = COLUMN
     await probe.redraw()
-    assert probe.alignment == LEFT
+    probe.assert_alignment(LEFT)
 
     for alignment in [RIGHT, CENTER, JUSTIFY]:
         widget.style.text_align = alignment
         await probe.redraw()
-        probe.assert_alignment_equivalent(probe.alignment, alignment)
+        probe.assert_alignment(alignment)
 
     # Clearing the alignment reverts to default alignment of LEFT
     del widget.style.text_align
     await probe.redraw()
-    assert probe.alignment == LEFT
+    probe.assert_alignment(LEFT)
 
     # If text direction is RTL, default alignment is RIGHT
     widget.style.text_direction = RTL
     await probe.redraw()
-    assert probe.alignment == RIGHT
+    probe.assert_alignment(RIGHT)
 
     # If text direction is expliclty LTR, default alignment is LEFT
     widget.style.text_direction = LTR
     await probe.redraw()
-    assert probe.alignment == LEFT
+    probe.assert_alignment(LEFT)
diff --git a/winforms/tests_backend/widgets/base.py b/winforms/tests_backend/widgets/base.py
index 84e254c57c..176f7195ce 100644
--- a/winforms/tests_backend/widgets/base.py
+++ b/winforms/tests_backend/widgets/base.py
@@ -24,8 +24,9 @@ def assert_container(self, container):
         else:
             raise ValueError(f"cannot find {self.native} in {container_native}")
 
-    def assert_alignment_equivalent(self, actual, expected):
+    def assert_alignment(self, expected):
         # Winforms doesn't have a "Justified" alignment; it falls back to LEFT
+        actual = self.alignment
         if expected == JUSTIFY:
             assert actual == LEFT
         else:

From 1b70eeec0d1d5f4d4762b8566ab01641737b03fa Mon Sep 17 00:00:00 2001
From: Malcolm Smith <smith@chaquo.com>
Date: Tue, 21 Mar 2023 17:55:10 +0000
Subject: [PATCH 11/21] Remove change note for issue which may not be
 completely fixed yet

---
 changes/1289.bugfix.rst | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 changes/1289.bugfix.rst

diff --git a/changes/1289.bugfix.rst b/changes/1289.bugfix.rst
deleted file mode 100644
index ae5e074a6a..0000000000
--- a/changes/1289.bugfix.rst
+++ /dev/null
@@ -1 +0,0 @@
-Label widgets now correctly resize after a change in label text.

From cdedf68a5a02becdacd6091d033ccbfc4c59ada7 Mon Sep 17 00:00:00 2001
From: Malcolm Smith <smith@chaquo.com>
Date: Tue, 21 Mar 2023 18:58:11 +0000
Subject: [PATCH 12/21] Remove unnecessary skips in base probes

---
 android/tests_backend/widgets/base.py | 13 -------------
 gtk/tests_backend/widgets/base.py     | 10 ----------
 2 files changed, 23 deletions(-)

diff --git a/android/tests_backend/widgets/base.py b/android/tests_backend/widgets/base.py
index 8a6c5dd0f1..f0bfab91fa 100644
--- a/android/tests_backend/widgets/base.py
+++ b/android/tests_backend/widgets/base.py
@@ -1,7 +1,6 @@
 import asyncio
 
 from java import dynamic_proxy
-from pytest import skip
 
 from android.view import ViewTreeObserver
 from toga.fonts import SYSTEM
@@ -71,18 +70,6 @@ async def redraw(self):
     def enabled(self):
         return self.native.isEnabled()
 
-    @property
-    def background_color(self):
-        skip("not implemented: background_color")
-
-    @property
-    def color(self):
-        skip("not implemented: color")
-
-    @property
-    def hidden(self):
-        skip("not implemented: hidden")
-
     @property
     def width(self):
         # Return the value in DP
diff --git a/gtk/tests_backend/widgets/base.py b/gtk/tests_backend/widgets/base.py
index d0fee7ffc4..f9004af7e6 100644
--- a/gtk/tests_backend/widgets/base.py
+++ b/gtk/tests_backend/widgets/base.py
@@ -1,7 +1,5 @@
 import asyncio
 
-from pytest import skip
-
 from toga_gtk.libs import Gtk
 
 from .properties import toga_color, toga_font
@@ -42,14 +40,6 @@ async def redraw(self):
         if self.widget.app.run_slow:
             await asyncio.sleep(1)
 
-    @property
-    def enabled(self):
-        skip("enabled probe not implemented")
-
-    @property
-    def hidden(self):
-        skip("hidden probe not implemented")
-
     @property
     def width(self):
         return self.native.get_allocation().width

From 0f798ccbc0ab72047fe9819466b2ea0866940b96 Mon Sep 17 00:00:00 2001
From: Malcolm Smith <smith@chaquo.com>
Date: Tue, 21 Mar 2023 20:39:46 +0000
Subject: [PATCH 13/21] iOS: round up size in Label.rehint to prevent lines
 being omitted

---
 changes/1501.bugfix.rst           | 1 +
 iOS/src/toga_iOS/widgets/label.py | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 changes/1501.bugfix.rst

diff --git a/changes/1501.bugfix.rst b/changes/1501.bugfix.rst
new file mode 100644
index 0000000000..b9c429e10d
--- /dev/null
+++ b/changes/1501.bugfix.rst
@@ -0,0 +1 @@
+iOS now supports newlines in Labels.
diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index eb20a964c4..7f64c38778 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -1,3 +1,5 @@
+from math import ceil
+
 from rubicon.objc import CGSize
 from travertino.size import at_least
 
@@ -39,5 +41,5 @@ def set_text(self, value):
     def rehint(self):
         fitting_size = self.native.systemLayoutSizeFittingSize(CGSize(0, 0))
         # print("REHINT label", self, fitting_size.width, fitting_size.height)
-        self.interface.intrinsic.width = at_least(fitting_size.width)
-        self.interface.intrinsic.height = fitting_size.height
+        self.interface.intrinsic.width = at_least(ceil(fitting_size.width))
+        self.interface.intrinsic.height = ceil(fitting_size.height)

From 025259db3c6b90efa387c94ed5dfb3a74fbdbec1 Mon Sep 17 00:00:00 2001
From: Malcolm Smith <smith@chaquo.com>
Date: Tue, 21 Mar 2023 21:01:03 +0000
Subject: [PATCH 14/21] Add empty label height test

---
 testbed/tests/widgets/test_label.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/testbed/tests/widgets/test_label.py b/testbed/tests/widgets/test_label.py
index d08790aca6..9eaf46c7a7 100644
--- a/testbed/tests/widgets/test_label.py
+++ b/testbed/tests/widgets/test_label.py
@@ -23,23 +23,26 @@ async def widget():
 
 
 async def test_multiline(widget, probe):
-    """If the label contains multiline text, it resizes"""
+    """If the label contains multiline text, it resizes vertically"""
 
     def make_lines(n):
         return "\n".join(f"line{i}" for i in range(n))
 
     widget.text = make_lines(1)
-
     await probe.redraw()
     line_height = probe.height
 
-    widget.text = make_lines(2)
+    # Empty text should not cause the widget to collapse.
+    widget.text = ""
+    await probe.redraw()
+    assert probe.height == line_height
 
+    widget.text = make_lines(2)
     await probe.redraw()
     assert probe.height == approx(line_height * 2, rel=0.1)
     line_spacing = probe.height - (line_height * 2)
 
-    for n in range(3, 10):
+    for n in range(3, 6):
         widget.text = make_lines(n)
         await probe.redraw()
         assert probe.height == approx(

From f2fb171cff437b8706a8dcb0665e224295309912 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 09:51:25 +0800
Subject: [PATCH 15/21] Remove the use of shadow handling in label.

---
 android/src/toga_android/widgets/label.py   |  3 +++
 cocoa/src/toga_cocoa/widgets/label.py       |  5 ++++-
 core/src/toga/widgets/label.py              | 18 ++++++++++++------
 core/tests/widgets/test_label.py            |  1 +
 dummy/src/toga_dummy/widgets/label.py       |  5 ++++-
 gtk/src/toga_gtk/widgets/label.py           |  5 ++++-
 iOS/src/toga_iOS/widgets/label.py           |  5 ++++-
 web/src/toga_web/widgets/label.py           |  3 +++
 winforms/src/toga_winforms/widgets/label.py |  5 ++++-
 9 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/android/src/toga_android/widgets/label.py b/android/src/toga_android/widgets/label.py
index ff70b35de6..60d523bb23 100644
--- a/android/src/toga_android/widgets/label.py
+++ b/android/src/toga_android/widgets/label.py
@@ -31,6 +31,9 @@ def create(self):
         self.native = TextView(self._native_activity)
         self.cache_textview_defaults()
 
+    def get_text(self):
+        return self.native.getText()
+
     def set_text(self, value):
         self.native.setText(value)
 
diff --git a/cocoa/src/toga_cocoa/widgets/label.py b/cocoa/src/toga_cocoa/widgets/label.py
index 746a13afe2..a686bc259b 100644
--- a/cocoa/src/toga_cocoa/widgets/label.py
+++ b/cocoa/src/toga_cocoa/widgets/label.py
@@ -26,8 +26,11 @@ def set_color(self, value):
     def set_font(self, font):
         self.native.font = font._impl.native
 
+    def get_text(self):
+        return self.native.stringValue
+
     def set_text(self, value):
-        self.native.stringValue = self.interface._text
+        self.native.stringValue = value
 
     def rehint(self):
         # Width & height of a label is known and fixed.
diff --git a/core/src/toga/widgets/label.py b/core/src/toga/widgets/label.py
index c44141f53f..77f86dc95a 100644
--- a/core/src/toga/widgets/label.py
+++ b/core/src/toga/widgets/label.py
@@ -26,15 +26,21 @@ def __init__(
 
     @property
     def text(self):
-        """The text displayed by the label."""
-        return self._text
+        """The text displayed by the label.
+
+        ``None``, and the Unicode codepoint U+200B (ZERO WIDTH SPACE), will be
+        interpreted and returned as an empty string. Any other object will be
+        converted to a string using ``str()``.
+
+        """
+        return self._impl.get_text()
 
     @text.setter
     def text(self, value):
-        if value is None:
-            self._text = ""
+        if value is None or value == "\u200B":
+            text = ""
         else:
-            self._text = str(value)
+            text = str(value)
 
-        self._impl.set_text(value)
+        self._impl.set_text(text)
         self.refresh()
diff --git a/core/tests/widgets/test_label.py b/core/tests/widgets/test_label.py
index 3f04a4e16c..81e3eedf02 100644
--- a/core/tests/widgets/test_label.py
+++ b/core/tests/widgets/test_label.py
@@ -26,6 +26,7 @@ def test_label_created(label):
         ("New Text", "New Text"),
         (12345, "12345"),
         (None, ""),
+        ("\u200B", ""),
         ("Contains\nsome\nnewlines", "Contains\nsome\nnewlines"),
     ],
 )
diff --git a/dummy/src/toga_dummy/widgets/label.py b/dummy/src/toga_dummy/widgets/label.py
index 9fb28f1972..1c654b249e 100644
--- a/dummy/src/toga_dummy/widgets/label.py
+++ b/dummy/src/toga_dummy/widgets/label.py
@@ -8,5 +8,8 @@ def create(self):
     def set_alignment(self, value):
         self._set_value("alignment", value)
 
+    def get_text(self):
+        return self._get_value("text")
+
     def set_text(self, value):
-        self._set_value("text", self.interface._text)
+        self._set_value("text", value)
diff --git a/gtk/src/toga_gtk/widgets/label.py b/gtk/src/toga_gtk/widgets/label.py
index aa1c04357c..d70ae4f80a 100644
--- a/gtk/src/toga_gtk/widgets/label.py
+++ b/gtk/src/toga_gtk/widgets/label.py
@@ -21,8 +21,11 @@ def set_alignment(self, value):
             justify
         )  # Aligns multiple lines relative to each other.
 
+    def get_text(self):
+        return self.native.get_text()
+
     def set_text(self, value):
-        self.native.set_text(self.interface._text)
+        self.native.set_text(value)
 
     def rehint(self):
         # print("REHINT", self,
diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index 7f64c38778..8226a128f7 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -33,8 +33,11 @@ def set_background_color(self, color):
     def set_font(self, font):
         self.native.font = font._impl.native
 
+    def get_text(self):
+        return self.native.text
+
     def set_text(self, value):
-        self.native.text = self.interface.text
+        self.native.text = value
         # Tell the text layout algorithm how many lines are allowed
         self.native.numberOfLines = len(self.interface.text.split("\n"))
 
diff --git a/web/src/toga_web/widgets/label.py b/web/src/toga_web/widgets/label.py
index 75d2ad9b74..1f81d0b333 100644
--- a/web/src/toga_web/widgets/label.py
+++ b/web/src/toga_web/widgets/label.py
@@ -5,6 +5,9 @@ class Label(Widget):
     def create(self):
         self.native = self._create_native_widget("span")
 
+    def get_text(self):
+        return self.native.innerHTML
+
     def set_text(self, value):
         self.native.innerHTML = value
 
diff --git a/winforms/src/toga_winforms/widgets/label.py b/winforms/src/toga_winforms/widgets/label.py
index 85aafee14b..0dd98d7f1e 100644
--- a/winforms/src/toga_winforms/widgets/label.py
+++ b/winforms/src/toga_winforms/widgets/label.py
@@ -13,8 +13,11 @@ def create(self):
     def set_alignment(self, value):
         self.native.TextAlign = TextAlignment(value)
 
+    def get_text(self):
+        return self.native.Text
+
     def set_text(self, value):
-        self.native.Text = self.interface._text
+        self.native.Text = value
 
     def set_font(self, font):
         self.native.Font = font._impl.native

From 28d370408fb58029f0726e80aff180c99173197b Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 10:20:13 +0800
Subject: [PATCH 16/21] Add test resilience against changes in text length.

---
 testbed/tests/data.py               | 15 ++++++++++++++-
 testbed/tests/widgets/test_label.py | 10 +++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/testbed/tests/data.py b/testbed/tests/data.py
index de1dcbbb12..0af222dfd1 100644
--- a/testbed/tests/data.py
+++ b/testbed/tests/data.py
@@ -1,6 +1,19 @@
 from toga.colors import rgba
 
-TEXTS = ["", " ", "a", "ab", "abc", "hello world", "hello\nworld", "你好, wørłd!"]
+# The text examples must both increase and decrease in size between examples to
+# ensure that reducing the size of a label doesn't prevent future labels from
+# increasing in size.
+TEXTS = [
+    "example",
+    "",
+    "a",
+    " ",
+    "ab",
+    "abc",
+    "hello world",
+    "hello\nworld",
+    "你好, wørłd!",
+]
 
 
 COLORS = [
diff --git a/testbed/tests/widgets/test_label.py b/testbed/tests/widgets/test_label.py
index 9eaf46c7a7..7d43b21ae5 100644
--- a/testbed/tests/widgets/test_label.py
+++ b/testbed/tests/widgets/test_label.py
@@ -26,16 +26,21 @@ async def test_multiline(widget, probe):
     """If the label contains multiline text, it resizes vertically"""
 
     def make_lines(n):
-        return "\n".join(f"line{i}" for i in range(n))
+        return "\n".join(f"This is line {i}" for i in range(n))
 
     widget.text = make_lines(1)
     await probe.redraw()
     line_height = probe.height
 
+    # Label should have a signficant width.
+    assert probe.width > 50
+
     # Empty text should not cause the widget to collapse.
     widget.text = ""
     await probe.redraw()
     assert probe.height == line_height
+    # Label should have almost 0 width
+    assert probe.width < 10
 
     widget.text = make_lines(2)
     await probe.redraw()
@@ -45,10 +50,13 @@ def make_lines(n):
     for n in range(3, 6):
         widget.text = make_lines(n)
         await probe.redraw()
+        # Label height should reflect the number of lines
         assert probe.height == approx(
             (line_height * n) + (line_spacing * (n - 1)),
             rel=0.1,
         )
+        # Label should have a signficant width.
+        assert probe.width > 50
 
 
 async def test_alignment(widget, probe):

From 572b07b6eaef4fecb93a84684272379a1824f992 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 11:20:34 +0800
Subject: [PATCH 17/21] Correct handling of empty labels on iOS.

---
 cocoa/src/toga_cocoa/widgets/label.py | 2 +-
 iOS/src/toga_iOS/widgets/label.py     | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/cocoa/src/toga_cocoa/widgets/label.py b/cocoa/src/toga_cocoa/widgets/label.py
index a686bc259b..a0e0461e67 100644
--- a/cocoa/src/toga_cocoa/widgets/label.py
+++ b/cocoa/src/toga_cocoa/widgets/label.py
@@ -27,7 +27,7 @@ def set_font(self, font):
         self.native.font = font._impl.native
 
     def get_text(self):
-        return self.native.stringValue
+        return str(self.native.stringValue)
 
     def set_text(self, value):
         self.native.stringValue = value
diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index 8226a128f7..1ca1168764 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -34,15 +34,17 @@ def set_font(self, font):
         self.native.font = font._impl.native
 
     def get_text(self):
-        return self.native.text
+        return str(self.native.text)
 
     def set_text(self, value):
+        if value == "":
+            value = "\u200B"
         self.native.text = value
         # Tell the text layout algorithm how many lines are allowed
         self.native.numberOfLines = len(self.interface.text.split("\n"))
 
     def rehint(self):
         fitting_size = self.native.systemLayoutSizeFittingSize(CGSize(0, 0))
-        # print("REHINT label", self, fitting_size.width, fitting_size.height)
+        # print(f"REHINT label {self} {self.get_text()!r} {fitting_size.width} {fitting_size.height}")
         self.interface.intrinsic.width = at_least(ceil(fitting_size.width))
         self.interface.intrinsic.height = ceil(fitting_size.height)

From 7864c9732f985d49bd7e7727431e7f2729f29a71 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 11:27:13 +0800
Subject: [PATCH 18/21] Correct the Pango negative size warning.

---
 gtk/src/toga_gtk/fonts.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/gtk/src/toga_gtk/fonts.py b/gtk/src/toga_gtk/fonts.py
index 15efc890d3..62f006f7db 100644
--- a/gtk/src/toga_gtk/fonts.py
+++ b/gtk/src/toga_gtk/fonts.py
@@ -1,4 +1,11 @@
-from toga.constants import BOLD, ITALIC, OBLIQUE, SMALL_CAPS, SYSTEM
+from toga.constants import (
+    BOLD,
+    ITALIC,
+    OBLIQUE,
+    SMALL_CAPS,
+    SYSTEM,
+    SYSTEM_DEFAULT_FONT_SIZE,
+)
 
 from .libs import Pango
 
@@ -27,8 +34,9 @@ def __init__(self, interface):
 
             font.set_family(family)
 
-            # Set font size
-            font.set_size(self.interface.size * Pango.SCALE)
+            # If this is a non-default font size, set the font size
+            if self.interface.size != SYSTEM_DEFAULT_FONT_SIZE:
+                font.set_size(self.interface.size * Pango.SCALE)
 
             # Set font style
             if self.interface.style == ITALIC:

From 2ffd585b130a39f152fd8f4204105fcf1b9d0c2a Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 11:46:05 +0800
Subject: [PATCH 19/21] Correct probe/API handling of ZWS.

---
 iOS/src/toga_iOS/widgets/label.py  | 5 ++++-
 iOS/tests_backend/widgets/label.py | 5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index 1ca1168764..d9f7e56738 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -34,7 +34,10 @@ def set_font(self, font):
         self.native.font = font._impl.native
 
     def get_text(self):
-        return str(self.native.text)
+        value = str(self.native.text)
+        if value == "\u200B":
+            return ""
+        return value
 
     def set_text(self, value):
         if value == "":
diff --git a/iOS/tests_backend/widgets/label.py b/iOS/tests_backend/widgets/label.py
index 2614e80f84..e2d870bbdc 100644
--- a/iOS/tests_backend/widgets/label.py
+++ b/iOS/tests_backend/widgets/label.py
@@ -10,7 +10,10 @@ class LabelProbe(SimpleProbe):
 
     @property
     def text(self):
-        return str(self.native.text)
+        value = str(self.native.text)
+        if value == "\u200B":
+            return ""
+        return value
 
     @property
     def color(self):

From 879f63e891e761dc27d8503db93c471aad0aade2 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 12:22:30 +0800
Subject: [PATCH 20/21] Remove a redundant documentation note.

---
 docs/reference/api/widgets/label.rst | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/docs/reference/api/widgets/label.rst b/docs/reference/api/widgets/label.rst
index 779c48aec6..e2dfcbb66d 100644
--- a/docs/reference/api/widgets/label.rst
+++ b/docs/reference/api/widgets/label.rst
@@ -25,10 +25,6 @@ Usage
 Notes
 -----
 
-* Any object can be provided as the text for the label. If the object is
-  ``None``, this will be converted into the empty string; any other non-string
-  object will be automatically converted to a string using ``str()``.
-
 * Winforms does not support an alignment value of ``JUSTIFIED``. If this
   alignment value is used, the label will default to left alignment.
 

From 15c3515760c489689da8fe47f192b5b061f3e8b4 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Wed, 22 Mar 2023 15:50:57 +0800
Subject: [PATCH 21/21] Relax width and height constraint during iOS rehinting
 to avoid word wrapping.

---
 iOS/src/toga_iOS/widgets/label.py | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/iOS/src/toga_iOS/widgets/label.py b/iOS/src/toga_iOS/widgets/label.py
index d9f7e56738..ad4674bfba 100644
--- a/iOS/src/toga_iOS/widgets/label.py
+++ b/iOS/src/toga_iOS/widgets/label.py
@@ -5,15 +5,15 @@
 
 from toga.colors import TRANSPARENT
 from toga_iOS.colors import native_color
-from toga_iOS.libs import NSLineBreakByWordWrapping, NSTextAlignment, UILabel
+from toga_iOS.libs import NSLineBreakByClipping, NSTextAlignment, UILabel
 from toga_iOS.widgets.base import Widget
 
 
 class Label(Widget):
     def create(self):
         self.native = UILabel.new()
-        # Word wrap the text inside the allocated space
-        self.native.lineBreakMode = NSLineBreakByWordWrapping
+        # We shouldn't ever word wrap; if faced with that option, clip.
+        self.native.lineBreakMode = NSLineBreakByClipping
 
         # Add the layout constraints
         self.add_constraints()
@@ -47,6 +47,17 @@ def set_text(self, value):
         self.native.numberOfLines = len(self.interface.text.split("\n"))
 
     def rehint(self):
+        # iOS text layout is an interplay between the layout constraints and the
+        # text layout algorithm. If the layout constraints fix the width, this
+        # can cause the text layout algorithm to try word wrapping to make text
+        # fit. To avoid this, temporarily relax the width and height constraint
+        # on the widget to "effectively infinite" values; they will be
+        # re-applied as part of the application of the newly hinted layout.
+        if self.constraints:
+            if self.constraints.width_constraint:
+                self.constraints.width_constraint.constant = 100000
+            if self.constraints.height_constraint:
+                self.constraints.height_constraint.constant = 100000
         fitting_size = self.native.systemLayoutSizeFittingSize(CGSize(0, 0))
         # print(f"REHINT label {self} {self.get_text()!r} {fitting_size.width} {fitting_size.height}")
         self.interface.intrinsic.width = at_least(ceil(fitting_size.width))