Rework test matrix and structure

tests/test_utils.py

@@ -0,0 +1,36 @@
+import json
+import os
+import imghdr
+from PIL import Image
+from django.test import SimpleTestCase
+
+from jsignature.utils import draw_signature
+
+DUMMY_VALUE = [{"x": [205, 210], "y": [59, 63]},
+               {"x": [205, 207], "y": [67, 64]}]
+DUMMY_STR_VALUE = json.dumps(DUMMY_VALUE)
+
+
+class UtilsTest(SimpleTestCase):
+
+    def test_inputs_bad_str_value(self):
+        self.assertRaises(ValueError, draw_signature, 'foo_bar')
+
+    def test_inputs_bad_type_value(self):
+        self.assertRaises(ValueError, draw_signature, object())
+
+    def test_inputs_good_list_value(self):
+        draw_signature(DUMMY_VALUE)
+
+    def test_inputs_good_str_value(self):
+        draw_signature(DUMMY_STR_VALUE)
+
+    def test_outputs_as_file(self):
+        output = draw_signature(DUMMY_VALUE, as_file=True)
+        self.assertTrue(os.path.isfile(output))
+        self.assertIsNotNone(imghdr.what(output))
+
+    def test_outputs_as_image(self):
+        output = draw_signature(DUMMY_VALUE)
+        self.assertTrue(issubclass(output.__class__, Image.Image))
+        self.assertTrue(all(output.getbbox()))