Add tests for generateimage template tag

Currently, these will fail because the temporary file cannot be pickled
in order to generate a hash.

setup.py

@@ -31,6 +31,7 @@ setup(
     zip_safe=False,
     include_package_data=True,
     tests_require=[
+        'beautifulsoup4==4.1.3',
         'nose==1.2.1',
         'nose-progressive==1.3',
         'django-nose==1.1',

tests/imagespecs.py

@@ -0,0 +1,8 @@
+from imagekit import ImageSpec, register
+
+
+class TestSpec(ImageSpec):
+    pass
+
+
+register.spec(TestSpec, 'testspec')

tests/test_generateimage_tag.py

@@ -0,0 +1,65 @@
+from bs4 import BeautifulSoup
+from django.template import Context, Template, TemplateSyntaxError
+from nose.tools import eq_, assert_not_in, raises, assert_not_equal
+from . import imagespecs
+from .utils import get_named_image_file
+
+
+def render_tag(ttag):
+    img = get_named_image_file()
+    img.name = 'tmp'  # FIXME: If we don't do this, we get a SuspiciousOperation
+    template = Template('{%% load imagekit %%}%s' % ttag)
+    context = Context({'img': img})
+    return template.render(context)
+
+
+def get_html_attrs(ttag):
+    return BeautifulSoup(render_tag(ttag)).img.attrs
+
+
+def test_img_tag():
+    ttag = r"""{% generateimage 'testspec' from=img %}"""
+    attrs = get_html_attrs(ttag)
+    expected_attrs = set(['src', 'width', 'height'])
+    eq_(set(attrs.keys()), expected_attrs)
+    for k in expected_attrs:
+        assert_not_equal(attrs[k].strip(), '')
+
+
+def test_img_tag_attrs():
+    ttag = r"""{% generateimage 'testspec' from=img with alt="Hello" %}"""
+    attrs = get_html_attrs(ttag)
+    eq_(attrs.get('alt'), 'Hello')
+
+
+@raises(TemplateSyntaxError)
+def test_dangling_with():
+    ttag = r"""{% generateimage 'testspec' from=img with %}"""
+    render_tag(ttag)
+
+
+@raises(TemplateSyntaxError)
+def test_with_assignment():
+    """
+    You can either use generateimage as an assigment tag or specify html attrs,
+    but not both.
+
+    """
+    ttag = r"""{% generateimage 'testspec' from=img with alt="Hello" as th %}"""
+    render_tag(ttag)
+
+
+def test_single_dimension_attr():
+    """
+    If you only provide one of width or height, the other should not be added.
+
+    """
+    ttag = r"""{% generateimage 'testspec' from=img with width="50" %}"""
+    attrs = get_html_attrs(ttag)
+    assert_not_in('height', attrs)
+
+
+def test_assignment_tag():
+    ttag = r"""{% generateimage 'testspec' from=img as th %} {{ th.url }}"""
+    html = render_tag(ttag)
+    assert_not_equal(html.strip(), '')