Fix ResourceWarning emitted during tests

Appeared in the form:

    ResourceWarning: unclosed file <_io.BufferedReader name='Tests/images/invalid-exif-without-x-resolution.jpg'>

Enable all warnings to always display during tests to help catch these
warnings earlier.

Author: jdufresne

Tests/test_file_jpeg.py

@@ -640,11 +640,11 @@ def test_invalid_exif(self):
 
     def test_invalid_exif_x_resolution(self):
         # When no x or y resolution is defined in EXIF
-        im = Image.open("Tests/images/invalid-exif-without-x-resolution.jpg")
+        with Image.open("Tests/images/invalid-exif-without-x-resolution.jpg") as im:
 
-        # This should return the default, and not a ValueError or
-        # OSError for an unidentified image.
-        self.assertEqual(im.info.get("dpi"), (72, 72))
+            # This should return the default, and not a ValueError or
+            # OSError for an unidentified image.
+            self.assertEqual(im.info.get("dpi"), (72, 72))
 
     def test_ifd_offset_exif(self):
         # Arrange

Tests/test_file_tiff_metadata.py

@@ -231,9 +231,9 @@ def test_ifd_unsigned_rational(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(max_long, reloaded.tag_v2[41493].numerator)
-        self.assertEqual(1, reloaded.tag_v2[41493].denominator)
+        with Image.open(out) as reloaded:
+            self.assertEqual(max_long, reloaded.tag_v2[41493].numerator)
+            self.assertEqual(1, reloaded.tag_v2[41493].denominator)
 
         # out of bounds of 4 byte unsigned long
         numerator = max_long + 1
@@ -243,9 +243,9 @@ def test_ifd_unsigned_rational(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(max_long, reloaded.tag_v2[41493].numerator)
-        self.assertEqual(1, reloaded.tag_v2[41493].denominator)
+        with Image.open(out) as reloaded:
+            self.assertEqual(max_long, reloaded.tag_v2[41493].numerator)
+            self.assertEqual(1, reloaded.tag_v2[41493].denominator)
 
     def test_ifd_signed_rational(self):
         im = hopper()
@@ -260,9 +260,9 @@ def test_ifd_signed_rational(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(numerator, reloaded.tag_v2[37380].numerator)
-        self.assertEqual(denominator, reloaded.tag_v2[37380].denominator)
+        with Image.open(out) as reloaded:
+            self.assertEqual(numerator, reloaded.tag_v2[37380].numerator)
+            self.assertEqual(denominator, reloaded.tag_v2[37380].denominator)
 
         numerator = -(2 ** 31)
         denominator = 2 ** 31 - 1
@@ -272,9 +272,9 @@ def test_ifd_signed_rational(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(numerator, reloaded.tag_v2[37380].numerator)
-        self.assertEqual(denominator, reloaded.tag_v2[37380].denominator)
+        with Image.open(out) as reloaded:
+            self.assertEqual(numerator, reloaded.tag_v2[37380].numerator)
+            self.assertEqual(denominator, reloaded.tag_v2[37380].denominator)
 
         # out of bounds of 4 byte signed long
         numerator = -(2 ** 31) - 1
@@ -285,9 +285,9 @@ def test_ifd_signed_rational(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(2 ** 31 - 1, reloaded.tag_v2[37380].numerator)
-        self.assertEqual(-1, reloaded.tag_v2[37380].denominator)
+        with Image.open(out) as reloaded:
+            self.assertEqual(2 ** 31 - 1, reloaded.tag_v2[37380].numerator)
+            self.assertEqual(-1, reloaded.tag_v2[37380].denominator)
 
     def test_ifd_signed_long(self):
         im = hopper()
@@ -298,8 +298,8 @@ def test_ifd_signed_long(self):
         out = self.tempfile("temp.tiff")
         im.save(out, tiffinfo=info, compression="raw")
 
-        reloaded = Image.open(out)
-        self.assertEqual(reloaded.tag_v2[37000], -60000)
+        with Image.open(out) as reloaded:
+            self.assertEqual(reloaded.tag_v2[37000], -60000)
 
     def test_empty_values(self):
         data = io.BytesIO(

tox.ini

@@ -14,7 +14,7 @@ commands =
     {envpython} setup.py clean
     {envpython} setup.py build_ext --inplace
     {envpython} selftest.py
-    {envpython} -m pytest {posargs}
+    {envpython} -W always -m pytest {posargs}
 deps =
     cffi
     numpy