Rewrote form widget tests as proper unittests.

This is preparation for landing the template-based widget rendering
patch and goes a long way to making these tests more useful for future
development. The old doctest heritage is strong here.

tests/forms_tests/widget_tests/test_multiwidget.py

@@ -0,0 +1,163 @@
+import copy
+from datetime import datetime
+
+from django.forms import (
+    CharField, FileInput, MultipleChoiceField, MultiValueField, MultiWidget,
+    RadioSelect, SelectMultiple, SplitDateTimeField, SplitDateTimeWidget,
+    TextInput,
+)
+
+from .base import WidgetTest
+
+
+class MyMultiWidget(MultiWidget):
+    def decompress(self, value):
+        if value:
+            return value.split('__')
+        return ['', '']
+
+
+class ComplexMultiWidget(MultiWidget):
+    def __init__(self, attrs=None):
+        widgets = (
+            TextInput(),
+            SelectMultiple(choices=WidgetTest.beatles),
+            SplitDateTimeWidget(),
+        )
+        super(ComplexMultiWidget, self).__init__(widgets, attrs)
+
+    def decompress(self, value):
+        if value:
+            data = value.split(',')
+            return [
+                data[0], list(data[1]), datetime.strptime(data[2], "%Y-%m-%d %H:%M:%S")
+            ]
+        return [None, None, None]
+
+    def format_output(self, rendered_widgets):
+        return '\n'.join(rendered_widgets)
+
+
+class ComplexField(MultiValueField):
+    def __init__(self, required=True, widget=None, label=None, initial=None):
+        fields = (
+            CharField(),
+            MultipleChoiceField(choices=WidgetTest.beatles),
+            SplitDateTimeField(),
+        )
+        super(ComplexField, self).__init__(
+            fields, required, widget, label, initial,
+        )
+
+    def compress(self, data_list):
+        if data_list:
+            return '%s,%s,%s' % (
+                data_list[0], ''.join(data_list[1]), data_list[2],
+            )
+        return None
+
+
+class DeepCopyWidget(MultiWidget):
+    """
+    Used to test MultiWidget.__deepcopy__().
+    """
+    def __init__(self, choices=[]):
+        widgets = [
+            RadioSelect(choices=choices),
+            TextInput,
+        ]
+        super(DeepCopyWidget, self).__init__(widgets)
+
+    def _set_choices(self, choices):
+        """
+        When choices are set for this widget, we want to pass those along to
+        the Select widget.
+        """
+        self.widgets[0].choices = choices
+
+    def _get_choices(self):
+        """
+        The choices for this widget are the Select widget's choices.
+        """
+        return self.widgets[0].choices
+    choices = property(_get_choices, _set_choices)
+
+
+class MultiWidgetTest(WidgetTest):
+
+    def test_text_inputs(self):
+        widget = MyMultiWidget(
+            widgets=(
+                TextInput(attrs={'class': 'big'}),
+                TextInput(attrs={'class': 'small'}),
+            )
+        )
+        self.check_html(widget, 'name', ['john', 'lennon'], html=(
+            '<input type="text" class="big" value="john" name="name_0" />'
+            '<input type="text" class="small" value="lennon" name="name_1" />'
+        ))
+        self.check_html(widget, 'name', 'john__lennon', html=(
+            '<input type="text" class="big" value="john" name="name_0" />'
+            '<input type="text" class="small" value="lennon" name="name_1" />'
+        ))
+        self.check_html(widget, 'name', 'john__lennon', attrs={'id': 'foo'}, html=(
+            '<input id="foo_0" type="text" class="big" value="john" name="name_0" />'
+            '<input id="foo_1" type="text" class="small" value="lennon" name="name_1" />'
+        ))
+
+    def test_constructor_attrs(self):
+        widget = MyMultiWidget(
+            widgets=(
+                TextInput(attrs={'class': 'big'}),
+                TextInput(attrs={'class': 'small'}),
+            ),
+            attrs={'id': 'bar'},
+        )
+        self.check_html(widget, 'name', ['john', 'lennon'], html=(
+            '<input id="bar_0" type="text" class="big" value="john" name="name_0" />'
+            '<input id="bar_1" type="text" class="small" value="lennon" name="name_1" />'
+        ))
+
+    def test_needs_multipart_true(self):
+        """
+        needs_multipart_form should be True if any widgets need it.
+        """
+        widget = MyMultiWidget(widgets=(TextInput(), FileInput()))
+        self.assertTrue(widget.needs_multipart_form)
+
+    def test_needs_multipart_false(self):
+        """
+        needs_multipart_form should be False if no widgets need it.
+        """
+        widget = MyMultiWidget(widgets=(TextInput(), TextInput()))
+        self.assertFalse(widget.needs_multipart_form)
+
+    def test_nested_multiwidget(self):
+        """
+        MultiWidgets can be composed of other MultiWidgets.
+        """
+        widget = ComplexMultiWidget()
+        self.check_html(widget, 'name', 'some text,JP,2007-04-25 06:24:00', html=(
+            """
+            <input type="text" name="name_0" value="some text" />
+            <select multiple="multiple" name="name_1">
+                <option value="J" selected="selected">John</option>
+                <option value="P" selected="selected">Paul</option>
+                <option value="G">George</option>
+                <option value="R">Ringo</option>
+            </select>
+            <input type="text" name="name_2_0" value="2007-04-25" />
+            <input type="text" name="name_2_1" value="06:24:00" />
+            """
+        ))
+
+    def test_deepcopy(self):
+        """
+        MultiWidget should define __deepcopy__() (#12048).
+        """
+        w1 = DeepCopyWidget(choices=[1, 2, 3])
+        w2 = copy.deepcopy(w1)
+        w2.choices = [4, 5, 6]
+        # w2 ought to be independent of w1, since MultiWidget ought
+        # to make a copy of its sub-widgets when it is copied.
+        self.assertEqual(w1.choices, [1, 2, 3])