Remove _errors and ghostscript test

tests/test_errors.py

@@ -74,21 +74,6 @@ def test_no_tables_found_warnings_suppressed():
             pytest.fail('Unexpected warning: {}'.format(warning_text))
 
 
-def test_ghostscript_not_found(monkeypatch):
-    import distutils
-
-    def _find_executable_patch(arg):
-        return ''
-
-    monkeypatch.setattr(distutils.spawn, 'find_executable', _find_executable_patch)
-
-    message = ('Please make sure that Ghostscript is installed and available'
-               ' on the PATH environment variable')
-    filename = os.path.join(testdir, 'foo.pdf')
-    with pytest.raises(Exception, message=message):
-        tables = camelot.read_pdf(filename)
-
-
 def test_no_password():
     filename = os.path.join(testdir, 'health_protected.pdf')
     message = 'file has not been decrypted'