diff --git a/src/natcap/invest/validation.py b/src/natcap/invest/validation.py
index b94ac2c35..01d22526b 100644
--- a/src/natcap/invest/validation.py
+++ b/src/natcap/invest/validation.py
@@ -166,8 +166,8 @@ def check_directory(dirpath, must_exist=True, permissions='rx', **kwargs):
         must_exist=True (bool): If ``True``, the directory at ``dirpath``
             must already exist on the filesystem.
         permissions='rx' (string): A string that includes the lowercase
-            characters ``r``, ``w`` and/or ``x``, indicating read, write, and execute
-            permissions (respectively) required for this directory.
+            characters ``r``, ``w`` and/or ``x``, indicating read, write, and
+            execute permissions (respectively) required for this directory.
 
     Returns:
         A string error message if an error was found.  ``None`` otherwise.
@@ -197,25 +197,27 @@ def check_directory(dirpath, must_exist=True, permissions='rx', **kwargs):
     if 'r' in permissions:
         try:
             os.scandir(dirpath).close()
-        except:
+        except OSError:
             return MESSAGES[MESSAGE_KEY].format(permission='read')
 
-    # Check for x access before checking for w, since w operations to a dir are dependent on x access
+    # Check for x access before checking for w,
+    # since w operations to a dir are dependent on x access
     if 'x' in permissions:
         try:
             cwd = os.getcwd()
             os.chdir(dirpath)
-            os.chdir(cwd)
-        except:
+        except OSError:
             return MESSAGES[MESSAGE_KEY].format(permission='execute')
+        finally:
+            os.chdir(cwd)
 
     if 'w' in permissions:
         try:
-            temp_path = os.path.join(dirpath, '__temp__workspace_validation_check.txt')
+            temp_path = os.path.join(dirpath, 'temp__workspace_validation.txt')
             with open(temp_path, 'w') as temp:
                 temp.close()
                 os.remove(temp_path)
-        except:
+        except OSError:
             return MESSAGES[MESSAGE_KEY].format(permission='write')
 
 
@@ -225,8 +227,8 @@ def check_file(filepath, permissions='r', **kwargs):
     Args:
         filepath (string): The filepath to validate.
         permissions='r' (string): A string that includes the lowercase
-            characters ``r``, ``w`` and/or ``x``, indicating read, write, and execute
-            permissions (respectively) required for this file.
+            characters ``r``, ``w`` and/or ``x``, indicating read, write, and
+            execute permissions (respectively) required for this file.
 
     Returns:
         A string error message if an error was found.  ``None`` otherwise.
diff --git a/tests/test_validation.py b/tests/test_validation.py
index 35da3a2ae..f5ad094f5 100644
--- a/tests/test_validation.py
+++ b/tests/test_validation.py
@@ -1,9 +1,6 @@
 """Testing module for validation."""
-import codecs
-import collections
 import functools
 import os
-import platform
 import shutil
 import stat
 import string
@@ -331,63 +328,91 @@ def test_workspace_not_exists(self):
         self.assertEqual(None, validation.check_directory(
             new_dir, must_exist=False, permissions='rwx'))
 
-@unittest.skipIf(sys.platform.startswith('win'), 'requires support for os.chmod(), which is unreliable on Windows')
+
+@unittest.skipIf(
+    sys.platform.startswith('win'),
+    'requires support for os.chmod(), which is unreliable on Windows')
 class DirectoryValidationMacOnly(unittest.TestCase):
     """Test Directory Permissions Validation."""
 
     def test_invalid_permissions_r(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing write and execute permissions."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing write and execute permissions."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IREAD)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='execute'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='execute'))
 
     def test_invalid_permissions_w(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing read and execute permissions."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing read and execute permissions."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IWRITE)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
 
     def test_invalid_permissions_x(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing read and write permissions."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing read and write permissions."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IEXEC)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
 
     def test_invalid_permissions_rw(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing execute permission."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing execute permission."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IREAD | stat.S_IWRITE)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='execute'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='execute'))
 
     def test_invalid_permissions_rx(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing write permission."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing write permission."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IREAD | stat.S_IEXEC)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='write'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='write'))
 
     def test_invalid_permissions_wx(self):
-        """Validation: when a folder must have read/write/execute permissions but is missing read permission."""
+        """Validation: when a folder must have read/write/execute
+        permissions but is missing read permission."""
         from natcap.invest import validation
 
         with tempfile.TemporaryDirectory() as tempdir:
             os.chmod(tempdir, stat.S_IWRITE | stat.S_IEXEC)
-            validation_warning = validation.check_directory(tempdir, permissions='rwx')
-            self.assertEqual(validation_warning, validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
+            validation_warning = validation.check_directory(tempdir,
+                                                            permissions='rwx')
+            self.assertEqual(
+                validation_warning,
+                validation.MESSAGES['NEED_PERMISSION_DIRECTORY'].format(permission='read'))
+
 
 class FileValidation(unittest.TestCase):
     """Test File Validator."""
@@ -598,7 +623,6 @@ def test_vector_projected_in_m(self):
 
     def test_wrong_geom_type(self):
         """Validation: checks that the vector's geometry type is correct."""
-        from natcap.invest import spec_utils
         from natcap.invest import validation
         driver = gdal.GetDriverByName('GPKG')
         filepath = os.path.join(self.workspace_dir, 'vector.gpkg')
@@ -1428,7 +1452,6 @@ def test_csv_raster_validation_missing_file(self):
                 })
         self.assertIn('File not found', str(cm.exception))
 
-
     def test_csv_raster_validation_not_projected(self):
         """validation: validate unprojected raster within csv column"""
         from natcap.invest import validation