Fix size on File object after optimizing

README.rst

@@ -5,8 +5,6 @@ django_optimized_image
 django_optimized_image is a simple Django library that allows optimization
 of images by using `TinyPNG <https://tinypng.com/>`_ or `Pillow <pillow.readthedocs.io/>`_.
 
-Detailed documentation is in the "docs" directory.
-
 Quick start
 -----------
 

optimized_image/tests/test_utils.py

@@ -1,16 +1,35 @@
-from factory.fuzzy import FuzzyText
 import io
 from unittest.mock import patch, Mock
 
-from django.core.files.uploadedfile import InMemoryUploadedFile
-from django.test import TestCase
+from django.core.files.uploadedfile import SimpleUploadedFile
+from django.test import TestCase, override_settings
 
 from . import factories
 from ..utils import optimize_from_buffer, optimize_legacy_images_in_model_fields
 
 
 class TestOptimizeFromBuffer(TestCase):
     """Test case for the mock_optimize_from_buffer() function."""
+
+    @override_settings(OPTIMIZED_IMAGE_METHOD="justtesting")
+    @patch('optimized_image.utils.is_testing_mode')
+    def test_changing_size(self, mock_is_testing_mode):
+        mock_is_testing_mode.return_value = False
+        TESTFILE = "small_kitten.jpeg"
+
+        data = SimpleUploadedFile(name=TESTFILE, content=open(TESTFILE, "rb").read())
+
+        initial_size = data.size
+        optimize_from_buffer(data)
+        resized_data_size = data.size
+        data.open()
+        actual_final_size = len(data.read())
+        self.assertEqual(actual_final_size, resized_data_size)
+        self.assertLess(
+            actual_final_size, initial_size,
+            msg="Test not valid - image was not reduced"
+        )
+
     @patch('optimized_image.utils.is_testing_mode')
     @patch('optimized_image.utils.Image')
     @patch('optimized_image.utils.tinify')
@@ -86,6 +105,8 @@ def test_settings(self, mock_tinify, mock_pil_image):
         """The OPTIMIZED_IMAGE_METHOD is used to determine whether Pillow or TinyPNG is used."""
         generic_model = factories.GenericModelFactory()
 
+        mock_tinify.from_buffer.return_value.to_buffer.return_value = b""
+
         with self.subTest(OPTIMIZED_IMAGE_METHOD='pillow'):
             with self.settings(
                 OPTIMIZED_IMAGE_METHOD='pillow',

optimized_image/utils.py

@@ -42,6 +42,20 @@ def optimize_from_buffer(data):
             data.seek(0)
             data.file.write(optimized_buffer)
             data.file.truncate()
+        elif settings.OPTIMIZED_IMAGE_METHOD == 'justtesting':
+            # Make a tiny image and use that instead of the input image.
+            # (justtesting is NOT a publicly allowed value, it's just for internal testing.)
+            bytes_io = BytesIO()
+            Image.new('RGB', (10, 10), "blue").save(bytes_io, format="JPEG")
+            data.seek(0)
+            data.file.write(bytes_io.getvalue())
+            data.file.truncate()
+        # Else - just don't change it
+        else:
+            return data
+
+        # We optimized it - fix the computed size
+        data.size = data.file.tell()
     return data
 
 
@@ -122,6 +136,10 @@ def optimize_legacy_images_in_model_fields(list_of_models, verbosity=0):
                             image_name = os.path.relpath(image_file.name, image_file.field.upload_to)
                             image_file.save(image_name, content_file)
                     except:
+                        if is_testing_mode():
+                            # This shouldn't actually happen, so if testing, let the exception continue
+                            # up the call chain so it makes the test fail.
+                            raise
                         # If the optimization failed for any reason, write this
                         # to stdout.
                         sys.stdout.write('\nOptimization failed for {}.'.format(image_file.name))

runtests.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+import sys
+import django
+from django.conf import settings
+
+if not settings.configured:
+    settings.configure(
+        DATABASES={
+            "default": {"ENGINE": "django.db.backends.sqlite3", "NAME": "test.db",}
+        },
+        MIDDLEWARE_CLASSES=(),
+        INSTALLED_APPS=("optimized_image", "not_optimized"),
+        SITE_ID=1,
+        ADMINS=(("Admin", "admin@example.com"),),
+        OPTIMIZED_IMAGE_METHOD="pillow",
+        TINYPNG_KEY="versecrettinypngkey",
+        BASE_DIR="",  # tells compatibility checker not to emit warning
+        TEMPLATES=[
+            {
+                "BACKEND": "django.template.backends.django.DjangoTemplates",
+                "DIRS": ["optimized_image/templates"],
+            }
+        ],
+    )
+
+
+def runtests():
+    django.setup()
+    from django.test.utils import get_runner
+
+    TestRunner = get_runner(settings)
+    test_runner = TestRunner(verbosity=1, interactive=True, failfast=True)
+    failures = test_runner.run_tests(["optimized_image"])
+    if failures:
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    runtests()

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {py35,py3,py37}-1.11.X,{py35,py3,py37}-2.0.X,{py35,py3,py37}-2.1.X
+envlist = py35,py36,py37
 
 [testenv]
 basepython =