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_datetimeinput.py

@@ -0,0 +1,63 @@
+from datetime import datetime
+
+from django.forms import DateTimeInput
+from django.test import override_settings
+from django.utils import translation
+
+from .base import WidgetTest
+
+
+class DateTimeInputTest(WidgetTest):
+    widget = DateTimeInput()
+
+    def test_render_none(self):
+        self.check_html(self.widget, 'date', None, '<input type="text" name="date" />')
+
+    def test_render_value(self):
+        """
+        The microseconds are trimmed on display, by default.
+        """
+        d = datetime(2007, 9, 17, 12, 51, 34, 482548)
+        self.assertEqual(str(d), '2007-09-17 12:51:34.482548')
+        self.check_html(self.widget, 'date', d, html=(
+            '<input type="text" name="date" value="2007-09-17 12:51:34" />'
+        ))
+        self.check_html(self.widget, 'date', datetime(2007, 9, 17, 12, 51, 34), html=(
+            '<input type="text" name="date" value="2007-09-17 12:51:34" />'
+        ))
+        self.check_html(self.widget, 'date', datetime(2007, 9, 17, 12, 51), html=(
+            '<input type="text" name="date" value="2007-09-17 12:51:00" />'
+        ))
+
+    def test_render_formatted(self):
+        """
+        Use 'format' to change the way a value is displayed.
+        """
+        widget = DateTimeInput(
+            format='%d/%m/%Y %H:%M', attrs={'type': 'datetime'},
+        )
+        d = datetime(2007, 9, 17, 12, 51, 34, 482548)
+        self.check_html(widget, 'date', d, html='<input type="datetime" name="date" value="17/09/2007 12:51" />')
+
+    @override_settings(USE_L10N=True)
+    @translation.override('de-at')
+    def test_l10n(self):
+        d = datetime(2007, 9, 17, 12, 51, 34, 482548)
+        self.check_html(self.widget, 'date', d, html=(
+            '<input type="text" name="date" value="17.09.2007 12:51:34" />'
+        ))
+
+    @override_settings(USE_L10N=True)
+    @translation.override('de-at')
+    def test_locale_aware(self):
+        d = datetime(2007, 9, 17, 12, 51, 34, 482548)
+        with self.settings(USE_L10N=False):
+            self.check_html(
+                self.widget, 'date', d,
+                html='<input type="text" name="date" value="2007-09-17 12:51:34" />',
+            )
+        with translation.override('es'):
+            self.check_html(
+                self.widget, 'date', d,
+                html='<input type="text" name="date" value="17/09/2007 12:51:34" />',
+            )