checker: Added checkers for too more empty lines - fix: #4

docs/rules/WSC008.rst

@@ -0,0 +1,15 @@
+WSC008: More than 2 empty lines
+================================
+
+Alerting for more than 2 empty lines after the firs and before the last non-empty lines.
+
+
+Example
+-------
+
+.. test-wsc:: examples/WSC008_more_empty_lines.py
+
+    In <PATH> line 10:
+        os.makedirs(self.__print_cache_dir, exist_ok=True)
+                                                          ^-- WSC008: More than 2 empty lines (+1)
+

examples/WSC008_more_empty_lines.py

@@ -0,0 +1,18 @@
+class LabelPrinter:
+    def __generate_pdf(self):
+        pdf_generator = _LabelPdfGenerator()
+        pdf_generator.generate_label(
+            self.__title, self.__data, self.__logo_path, config.App.LABEL_BORDER,
+            output_path=self.__pdf_path)
+
+
+    def __prepare_print_cache_dir(self):
+        os.makedirs(self.__print_cache_dir, exist_ok=True)
+
+
+
+    def __get_pdf_path(self) -> str:
+        pdf_name = self.__pdf_name_template.format(
+            data=self.__data,
+            title_hash=hashlib.sha1(self.__title.encode()).hexdigest())
+        return os.path.join(self.__print_cache_dir, pdf_name)

examples/multiple_problems.py

@@ -12,9 +12,12 @@ def __generate_pdf(self):
             self.__title, self.__data, self.__logo_path, config.App.LABEL_BORDER,
             output_path=self.__pdf_path)
 
+
     def __prepare_print_cache_dir(self):
 		os.makedirs(self.__cache_dir, exist_ok=True)
 
+
+
     def __get_pdf_path(self) -> str:
         pdf_name = self.__pdf_name_template.format(
             data=self.__data,

tests/performance/test_checker_performance.py

@@ -166,3 +166,18 @@ def test_wsc007(benchmark, text, expected_rules, expected_issue_count):
     File begins with newline
     """
     _measure(benchmark, text, expected_rules, expected_issue_count)
+
+
+@parametrize_with_names('text,expected_rules,expected_issue_count', {
+    'head_empty-3':     [_text(head=_line(suffix=DEFAULT_EOL * 3)),     ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+    'head_empty-21':    [_text(head=_line(suffix=DEFAULT_EOL * 21)),    ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+    'center_empty-3':   [_text(center=_line(suffix=DEFAULT_EOL * 3)),   ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+    'center_empty-21':  [_text(center=_line(suffix=DEFAULT_EOL * 21)),  ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+    'foot_empty-3':     [_text(foot=_line(prefix=DEFAULT_EOL * 3)),     ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+    'foot_empty-21':    [_text(foot=_line(prefix=DEFAULT_EOL * 21)),    ['WSC008'], CHECK_COUNT],   # noqa: E241,E501
+})
+def test_wsc008(benchmark, text, expected_rules, expected_issue_count):
+    """
+    More than 2 empty lines
+    """
+    _measure(benchmark, text, expected_rules, expected_issue_count)

tests/unit/checker/test_rules.py

@@ -216,6 +216,38 @@ def test_non_spaces_in_indentation_is_bad(self, checker, content, col):
         ] == checker.issues
 
 
+class TestEmptyLines(object):
+    """
+    WSC008: More than 2 empty lines
+    """
+    @pytest.mark.parametrize('text', [
+        'cherry\napple\n',
+        'cherry\n\napple\n',
+        'cherry\n\n\napple\n',
+    ])
+    def test_valid_amount_of_empty_lines(self, checker, text):
+        checker.check_text(text)
+        assert [] == checker.issues
+
+    def test_3_empty_lines(self, checker):
+        checker.check_text('cherry\n\n\n\napple\n')
+        assert [
+            {
+                'rule': 'WSC008', 'path': '<string>', 'line': 1, 'col': 7,
+                'context': '', 'message_suffix': '(+1)'
+            },
+        ] == checker.issues
+
+    def test_5_empty_lines(self, checker):
+        checker.check_text('cherry\n\n\n\n\n\napple\n')
+        assert [
+            {
+                'rule': 'WSC008', 'path': '<string>', 'line': 1, 'col': 7,
+                'context': '', 'message_suffix': '(+3)'
+            },
+        ] == checker.issues
+
+
 class TestComplexCases(object):
     def test_multiple_issues(self, checker):
         checker.check_text('\n\n \tpineapple \rbanana')

wscheck/checker.py

@@ -8,6 +8,7 @@
     'WSC005': 'No newline at end of file',
     'WSC006': 'Too many newline at end of file',
     'WSC007': 'File begins with newline',
+    'WSC008': 'More than 2 empty lines',
 }
 
 
@@ -82,8 +83,11 @@ def _check_by_lines(self, source_path, lines):
         :type source_path: str
         :type lines: list
         """
+        empty_lines = 0
+
         for line, line_text_eol in enumerate(lines, start=1):
             line_text, line_eol = line_text_eol
+            stripped_line_text = line_text.strip()
 
             if 'WSC001' in self._rules:
                 if not line_eol == '' and not line_eol == '\n':
@@ -96,9 +100,17 @@ def _check_by_lines(self, source_path, lines):
                     self._add_issue(rule='WSC002', path=source_path, line=line,
                                     col=tailing_whitespace_match.start() + 1, context=line_text)
 
-            if line_text.strip() == '':
+            if stripped_line_text == '':
+                empty_lines += 1
                 continue
 
+            if 'WSC008' in self._rules:
+                if empty_lines > 2:
+                    self._add_issue(rule='WSC008', path=source_path, line=line - empty_lines, col=1,
+                                    context=lines[line - empty_lines + 1][0],
+                                    message_suffix='(+{})'.format(empty_lines - 2))
+                empty_lines = 0
+
             indent_match = self._LINE_INDENT_TEMPLATE.match(line_text)
             if indent_match is not None:
                 line_indent = indent_match.group()