adafruit · kattni · Mar 16, 2021 · Mar 16, 2021 · Mar 16, 2021
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -23,7 +23,7 @@ repos:
     -   id: pylint
         name: pylint (library code)
         types: [python]
-        exclude: "^(docs/|examples/|setup.py$)"
+        exclude: "^(docs/|tests/|examples/|setup.py$)"
 -   repo: local
     hooks:
     -   id: pylint_examples
@@ -32,3 +32,11 @@ repos:
         entry: /usr/bin/env bash -c
         args: ['([[ ! -d "examples" ]] || for example in $(find . -path "./examples/*.py"); do pylint --disable=missing-docstring,invalid-name $example; done)']
         language: system
+-   repo: local
+    hooks:
+    -   id: pylint_tests
+        name: pylint (tests code)
+        description: Run pylint rules on "tests/*.py" files
+        entry: /usr/bin/env bash -c
+        args: ['([[ ! -d "tests" ]] || for test in $(find . -path "./tests/*.py"); do pylint --disable=missing-docstring $test; done)']
+        language: system
diff --git a/adafruit_imageload/bmp/__init__.py b/adafruit_imageload/bmp/__init__.py
@@ -32,9 +32,9 @@ def load(file, *, bitmap=None, palette=None):
     # bmp_header_length = int.from_bytes(file.read(4), 'little')
     # print(bmp_header_length)
     file.seek(0x12)  # Width of the bitmap in pixels
-    width = int.from_bytes(file.read(4), "little")
+    _width = int.from_bytes(file.read(4), "little")
     try:
-        height = int.from_bytes(file.read(4), "little")
+        _height = int.from_bytes(file.read(4), "little")
     except OverflowError as error:
         raise NotImplementedError(
             "Negative height BMP files are not supported on builds without longint"
@@ -58,8 +58,8 @@ def load(file, *, bitmap=None, palette=None):
 
     return indexed.load(
         file,
-        width,
-        height,
+        _width,
+        _height,
         data_start,
         colors,
         color_depth,

diff --git a/adafruit_imageload/pnm/pgm/ascii.py b/adafruit_imageload/pnm/pgm/ascii.py
@@ -21,7 +21,7 @@ def load(file, width, height, bitmap=None, palette=None):
     Load a PGM ascii file (P2)
     """
     data_start = file.tell()  # keep this so we can rewind
-    palette_colors = set()
+    _palette_colors = set()
     pixel = bytearray()
     # build a set of all colors present in the file, so palette and bitmap can be constructed
     while True:
@@ -30,14 +30,14 @@ def load(file, width, height, bitmap=None, palette=None):
             break
         if not byte.isdigit():
             int_pixel = int("".join(["%c" % char for char in pixel]))
-            palette_colors.add(int_pixel)
+            _palette_colors.add(int_pixel)
             pixel = bytearray()
         pixel += byte
     if palette:
-        palette = build_palette(palette, palette_colors)
+        palette = build_palette(palette, _palette_colors)
     if bitmap:
-        bitmap = bitmap(width, height, len(palette_colors))
-        palette_colors = list(palette_colors)
+        bitmap = bitmap(width, height, len(_palette_colors))
+        _palette_colors = list(_palette_colors)
         file.seek(data_start)
         for y in range(height):
             for x in range(width):
@@ -48,11 +48,11 @@ def load(file, width, height, bitmap=None, palette=None):
                         break
                     pixel += byte
                 int_pixel = int("".join(["%c" % char for char in pixel]))
-                bitmap[x, y] = palette_colors.index(int_pixel)
+                bitmap[x, y] = _palette_colors.index(int_pixel)
     return bitmap, palette
 
 
-def build_palette(palette_class, palette_colors):
+def build_palette(palette_class, palette_colors):  # pylint: disable=duplicate-code
     """
     construct the Palette, and populate it with the set of palette_colors
     """

diff --git a/adafruit_imageload/pnm/pgm/binary.py b/adafruit_imageload/pnm/pgm/binary.py
@@ -44,7 +44,7 @@ def build_palette(palette_class, palette_colors):
     """
     construct the Palette, and populate it with the set of palette_colors
     """
-    palette = palette_class(len(palette_colors))
+    _palette = palette_class(len(palette_colors))
     for counter, color in enumerate(palette_colors):
-        palette[counter] = bytes([color, color, color])
-    return palette
+        _palette[counter] = bytes([color, color, color])
+    return _palette
diff --git a/tests/displayio_shared_bindings.py b/tests/displayio_shared_bindings.py
@@ -24,8 +24,8 @@
 ====================================================
 
 The classes in this file are designed to emulate Circuitpython's displayio classes
-for Bitmap and Palette. These mimic classes should have the same methods and interface as the real interface,
-but with extra validation checks, warnings, and messages to facilitate debugging.
+for Bitmap and Palette. These mimic classes should have the same methods and interface as the real
+interface, but with extra validation checks, warnings, and messages to facilitate debugging.
 
 Code that can be run successfully against these classes will have a good chance of
  working correctly on hardware running Circuitpython, but without needing to upload code to a board
@@ -37,7 +37,7 @@
 from typing import Union
 
 
-class Bitmap_C_Interface(object):
+class Bitmap_C_Interface:
     """
     A class to simulate the displayio.Bitmap class for testing, based on
     https://circuitpython.readthedocs.io/en/latest/shared-bindings/displayio/Bitmap.html
@@ -88,8 +88,10 @@ def __getitem__(self, item: Union[tuple, int]) -> bytearray:
             raise RuntimeError(f"get position out of range {item}")
         try:
             return self.data[item]
-        except KeyError:
-            raise RuntimeError("no data at {} [{}]".format(self._decode(item), item))
+        except KeyError as err:
+            raise RuntimeError(
+                "no data at {} [{}]".format(self._decode(item), item)
+            ) from err
 
     def validate(self, detect_empty_image=True) -> None:
         """
@@ -103,8 +105,8 @@ def validate(self, detect_empty_image=True) -> None:
             for x in range(self.width):
                 try:
                     seen_colors.add(self[x, y])
-                except KeyError:
-                    raise ValueError(f"missing data at {x},{y}")
+                except KeyError as err:
+                    raise ValueError(f"missing data at {x},{y}") from err
         if detect_empty_image and len(seen_colors) < 2:
             raise ValueError(
                 "image detected as only one color. set detect_empty_image=False to ignore"
@@ -131,7 +133,7 @@ def __str__(self) -> str:
         return out
 
 
-class Palette_C_Interface(object):
+class Palette_C_Interface:
     """
     A class to simulates the displayio.Palette class for testing, based on
     https://circuitpython.readthedocs.io/en/latest/shared-bindings/displayio/Palette.html
@@ -191,8 +193,10 @@ def validate(self):
         for i in range(self.num_colors):
             try:
                 self.colors
-            except IndexError:
-                raise ValueError("missing color `{}` in palette color list".format(i))
+            except IndexError as err:
+                raise ValueError(
+                    "missing color `{}` in palette color list".format(i)
+                ) from err
 
     def __str__(self):
         """

diff --git a/tests/test_palette_c_interface.py b/tests/test_palette_c_interface.py
@@ -33,13 +33,16 @@
 
 
 class TestPalette_C_Interface(TestCase):
-    def test_init_mono(self):
+    @staticmethod
+    def test_init_mono():
         Palette_C_Interface(1)
 
-    def test_init_color(self):
+    @staticmethod
+    def test_init_color():
         Palette_C_Interface(256)
 
-    def test_set_int(self):
+    @staticmethod
+    def test_set_int():
         palette = Palette_C_Interface(1)
         palette[0] = 0xFFFFFF
 
@@ -48,7 +51,8 @@ def test_get_int(self):
         palette[0] = 0xFFFFFF
         self.assertEqual(0xFFFFFF, palette[0])
 
-    def test_set_byte(self):
+    @staticmethod
+    def test_set_byte():
         palette = Palette_C_Interface(1)
         palette[0] = b"\xFF\xFF\xFF"
 
@@ -57,7 +61,8 @@ def test_get_byte(self):
         palette[0] = b"\xFF\xFF\xFF"
         self.assertEqual(b"\xFF\xFF\xFF", palette[0])
 
-    def test_set_bytearray(self):
+    @staticmethod
+    def test_set_bytearray():
         palette = Palette_C_Interface(1)
         palette[0] = bytearray(b"\xFF\xFF\xFF")
 
@@ -66,20 +71,21 @@ def test_prevents_out_of_range(self):
         try:
             palette[1] = 0xFFFFFF
             self.fail("exception should have already thrown")
-        except ValueError as e:
-            if "greater than allowed" not in str(e):
+        except ValueError as err:
+            if "greater than allowed" not in str(err):
                 raise
 
     def test_prevents_set_non_allowed(self):
         palette = Palette_C_Interface(1)
         try:
             palette[0] = "\xFF\xFF\xFF"  # attempt with a string, which is not allowed
             self.fail("exception should have thrown")
-        except ValueError as e:
-            if "should be" not in str(e):
+        except ValueError as err:
+            if "should be" not in str(err):
                 raise
 
-    def test_validate_success(self):
+    @staticmethod
+    def test_validate_success():
         palette = Palette_C_Interface(1)
         palette[0] = b"\xFF\xFF\xFF"
         palette.validate()
@@ -90,11 +96,12 @@ def test_validate_fails(self):
         try:
             palette.validate()
             self.fail("exception should have thrown")
-        except IndexError as e:
-            if "palette was initialized" not in str(e):
+        except IndexError as err:
+            if "palette was initialized" not in str(err):
                 raise
 
-    def test_str(self):
+    @staticmethod
+    def test_str():
         palette = Palette_C_Interface(1)
         palette[0] = b"\xFF\xFF\xFF"
         print(str(palette))
diff --git a/tests/test_pbm_load.py b/tests/test_pbm_load.py
@@ -35,14 +35,14 @@
 
 
 class TestPbmLoad(TestCase):
-    def test_load_fails_with_no_header_data(self):
+    def test_load_fails_with_no_header_data(self):  # pylint: disable=invalid-name
         file = BytesIO(b"some initial binary data: \x00\x01")
         try:
             pnm.load(
                 file, b"P1", bitmap=Bitmap_C_Interface, palette=Palette_C_Interface
             )
             self.fail("should have failed")
-        except Exception as caught_exception:
+        except Exception as caught_exception:  # pylint: disable=broad-except
             if "Unsupported image format" not in str(caught_exception):
                 raise
 
@@ -102,7 +102,7 @@ def test_load_works_p4_binary(self):
         self.assertEqual(15, bitmap.height)
         bitmap.validate()
 
-    def test_load_works_p4_binary_high_res(self):
+    def test_load_works_p4_binary_high_res(self):  # pylint: disable=invalid-name
         test_file = os.path.join(
             os.path.dirname(__file__),
             "..",