Fix bugs in draw_signature and add tests

jsignature/tests/utils.py

@@ -0,0 +1,32 @@
+import json
+import os
+import imghdr
+from PIL import Image
+from django.test import SimpleTestCase
+
+from ..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(self):
+        # Bad str value
+        self.assertRaises(ValueError, draw_signature, 'foo_bar')
+        # Bad type value
+        self.assertRaises(ValueError, draw_signature, object())
+        # Good list value
+        draw_signature(DUMMY_VALUE)
+        # Good str value
+        draw_signature(DUMMY_STR_VALUE)
+
+    def test_outputs(self):
+        # As a file
+        output = draw_signature(DUMMY_VALUE, as_file=True)
+        self.assertTrue(os.path.isfile(output))
+        self.assertIsNotNone(imghdr.what(output))
+        # As an Image
+        output = draw_signature(DUMMY_VALUE)
+        self.assertTrue(issubclass(output.__class__, Image.Image))
+        self.assertTrue(all(output.getbbox()))