Parametrize tests

Tests/test_file_apng.py

@@ -325,21 +325,23 @@ def open():
     pytest.warns(UserWarning, open)
 
 
-def test_apng_sequence_errors():
-    test_files = [
+@pytest.mark.parametrize(
+    "f",
+    (
         "sequence_start.png",
         "sequence_gap.png",
         "sequence_repeat.png",
         "sequence_repeat_chunk.png",
         "sequence_reorder.png",
         "sequence_reorder_chunk.png",
         "sequence_fdat_fctl.png",
-    ]
-    for f in test_files:
-        with pytest.raises(SyntaxError):
-            with Image.open(f"Tests/images/apng/{f}") as im:
-                im.seek(im.n_frames - 1)
-                im.load()
+    ),
+)
+def test_apng_sequence_errors(f):
+    with pytest.raises(SyntaxError):
+        with Image.open(f"Tests/images/apng/{f}") as im:
+            im.seek(im.n_frames - 1)
+            im.load()
 
 
 def test_apng_save(tmp_path):

Tests/test_file_container.py

@@ -1,3 +1,5 @@
+import pytest
+
 from PIL import ContainerIO, Image
 
 from .helper import hopper
@@ -59,89 +61,89 @@ def test_seek_mode_2():
         assert container.tell() == 100
 
 
-def test_read_n0():
+@pytest.mark.parametrize("bytesmode", (True, False))
+def test_read_n0(bytesmode):
     # Arrange
-    for bytesmode in (True, False):
-        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
-            container = ContainerIO.ContainerIO(fh, 22, 100)
+    with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+        container = ContainerIO.ContainerIO(fh, 22, 100)
 
-            # Act
-            container.seek(81)
-            data = container.read()
+        # Act
+        container.seek(81)
+        data = container.read()
 
-            # Assert
-            if bytesmode:
-                data = data.decode()
-            assert data == "7\nThis is line 8\n"
+        # Assert
+        if bytesmode:
+            data = data.decode()
+        assert data == "7\nThis is line 8\n"
 
 
-def test_read_n():
+@pytest.mark.parametrize("bytesmode", (True, False))
+def test_read_n(bytesmode):
     # Arrange
-    for bytesmode in (True, False):
-        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
-            container = ContainerIO.ContainerIO(fh, 22, 100)
+    with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+        container = ContainerIO.ContainerIO(fh, 22, 100)
 
-            # Act
-            container.seek(81)
-            data = container.read(3)
+        # Act
+        container.seek(81)
+        data = container.read(3)
 
-            # Assert
-            if bytesmode:
-                data = data.decode()
-            assert data == "7\nT"
+        # Assert
+        if bytesmode:
+            data = data.decode()
+        assert data == "7\nT"
 
 
-def test_read_eof():
+@pytest.mark.parametrize("bytesmode", (True, False))
+def test_read_eof(bytesmode):
     # Arrange
-    for bytesmode in (True, False):
-        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
-            container = ContainerIO.ContainerIO(fh, 22, 100)
+    with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+        container = ContainerIO.ContainerIO(fh, 22, 100)
 
-            # Act
-            container.seek(100)
-            data = container.read()
+        # Act
+        container.seek(100)
+        data = container.read()
 
-            # Assert
-            if bytesmode:
-                data = data.decode()
-            assert data == ""
+        # Assert
+        if bytesmode:
+            data = data.decode()
+        assert data == ""
 
 
-def test_readline():
+@pytest.mark.parametrize("bytesmode", (True, False))
+def test_readline(bytesmode):
     # Arrange
-    for bytesmode in (True, False):
-        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
-            container = ContainerIO.ContainerIO(fh, 0, 120)
+    with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+        container = ContainerIO.ContainerIO(fh, 0, 120)
 
-            # Act
-            data = container.readline()
+        # Act
+        data = container.readline()
 
-            # Assert
-            if bytesmode:
-                data = data.decode()
-            assert data == "This is line 1\n"
+        # Assert
+        if bytesmode:
+            data = data.decode()
+        assert data == "This is line 1\n"
 
 
-def test_readlines():
+@pytest.mark.parametrize("bytesmode", (True, False))
+def test_readlines(bytesmode):
     # Arrange
-    for bytesmode in (True, False):
-        expected = [
-            "This is line 1\n",
-            "This is line 2\n",
-            "This is line 3\n",
-            "This is line 4\n",
-            "This is line 5\n",
-            "This is line 6\n",
-            "This is line 7\n",
-            "This is line 8\n",
-        ]
-        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
-            container = ContainerIO.ContainerIO(fh, 0, 120)
-
-            # Act
-            data = container.readlines()
-
-            # Assert
-            if bytesmode:
-                data = [line.decode() for line in data]
-            assert data == expected
+    expected = [
+        "This is line 1\n",
+        "This is line 2\n",
+        "This is line 3\n",
+        "This is line 4\n",
+        "This is line 5\n",
+        "This is line 6\n",
+        "This is line 7\n",
+        "This is line 8\n",
+    ]
+    with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+        container = ContainerIO.ContainerIO(fh, 0, 120)
+
+        # Act
+        data = container.readlines()
+
+        # Assert
+        if bytesmode:
+            data = [line.decode() for line in data]
+        assert data == expected

Tests/test_file_im.py

@@ -78,15 +78,12 @@ def test_eoferror():
         im.seek(n_frames - 1)
 
 
-def test_roundtrip(tmp_path):
-    def roundtrip(mode):
-        out = str(tmp_path / "temp.im")
-        im = hopper(mode)
-        im.save(out)
-        assert_image_equal_tofile(im, out)
-
-    for mode in ["RGB", "P", "PA"]:
-        roundtrip(mode)
+@pytest.mark.parametrize("mode", ("RGB", "P", "PA"))
+def test_roundtrip(mode, tmp_path):
+    out = str(tmp_path / "temp.im")
+    im = hopper(mode)
+    im.save(out)
+    assert_image_equal_tofile(im, out)
 
 
 def test_save_unsupported_mode(tmp_path):

Tests/test_file_libtiff.py

@@ -135,50 +135,50 @@ def test_adobe_deflate_tiff(self):
 
             assert_image_equal_tofile(im, "Tests/images/tiff_adobe_deflate.png")
 
-    def test_write_metadata(self, tmp_path):
+    @pytest.mark.parametrize("legacy_api", (False, True))
+    def test_write_metadata(self, legacy_api, tmp_path):
         """Test metadata writing through libtiff"""
-        for legacy_api in [False, True]:
-            f = str(tmp_path / "temp.tiff")
-            with Image.open("Tests/images/hopper_g4.tif") as img:
-                img.save(f, tiffinfo=img.tag)
-
-                if legacy_api:
-                    original = img.tag.named()
-                else:
-                    original = img.tag_v2.named()
-
-            # PhotometricInterpretation is set from SAVE_INFO,
-            # not the original image.
-            ignored = [
-                "StripByteCounts",
-                "RowsPerStrip",
-                "PageNumber",
-                "PhotometricInterpretation",
-            ]
-
-            with Image.open(f) as loaded:
-                if legacy_api:
-                    reloaded = loaded.tag.named()
-                else:
-                    reloaded = loaded.tag_v2.named()
-
-            for tag, value in itertools.chain(reloaded.items(), original.items()):
-                if tag not in ignored:
-                    val = original[tag]
-                    if tag.endswith("Resolution"):
-                        if legacy_api:
-                            assert val[0][0] / val[0][1] == (
-                                4294967295 / 113653537
-                            ), f"{tag} didn't roundtrip"
-                        else:
-                            assert val == 37.79000115940079, f"{tag} didn't roundtrip"
+        f = str(tmp_path / "temp.tiff")
+        with Image.open("Tests/images/hopper_g4.tif") as img:
+            img.save(f, tiffinfo=img.tag)
+
+            if legacy_api:
+                original = img.tag.named()
+            else:
+                original = img.tag_v2.named()
+
+        # PhotometricInterpretation is set from SAVE_INFO,
+        # not the original image.
+        ignored = [
+            "StripByteCounts",
+            "RowsPerStrip",
+            "PageNumber",
+            "PhotometricInterpretation",
+        ]
+
+        with Image.open(f) as loaded:
+            if legacy_api:
+                reloaded = loaded.tag.named()
+            else:
+                reloaded = loaded.tag_v2.named()
+
+        for tag, value in itertools.chain(reloaded.items(), original.items()):
+            if tag not in ignored:
+                val = original[tag]
+                if tag.endswith("Resolution"):
+                    if legacy_api:
+                        assert val[0][0] / val[0][1] == (
+                            4294967295 / 113653537
+                        ), f"{tag} didn't roundtrip"
                     else:
-                        assert val == value, f"{tag} didn't roundtrip"
+                        assert val == 37.79000115940079, f"{tag} didn't roundtrip"
+                else:
+                    assert val == value, f"{tag} didn't roundtrip"
 
-            # https://github.com/python-pillow/Pillow/issues/1561
-            requested_fields = ["StripByteCounts", "RowsPerStrip", "StripOffsets"]
-            for field in requested_fields:
-                assert field in reloaded, f"{field} not in metadata"
+        # https://github.com/python-pillow/Pillow/issues/1561
+        requested_fields = ["StripByteCounts", "RowsPerStrip", "StripOffsets"]
+        for field in requested_fields:
+            assert field in reloaded, f"{field} not in metadata"
 
     @pytest.mark.valgrind_known_error(reason="Known invalid metadata")
     def test_additional_metadata(self, tmp_path):