MarkdownBear: Add validate-links plugin

Closes coala#924

bears/markdown/MarkdownBear.py

@@ -21,7 +21,8 @@ class MarkdownBear:
 
     LANGUAGES = {'Markdown'}
     REQUIREMENTS = {NpmRequirement('remark-cli', '2'),
-                    NpmRequirement('remark-lint', '5')}
+                    NpmRequirement('remark-lint', '5'),
+                    NpmRequirement('remark-validate-links', '5')}
     AUTHORS = {'The coala developers'}
     AUTHORS_EMAILS = {'[email protected]'}
     LICENSE = 'AGPL-3.0'
@@ -65,7 +66,8 @@ def create_arguments(filename, file, config_file,
                          horizontal_rule: str='*',
                          horizontal_rule_spaces: bool=False,
                          horizontal_rule_repeat: int=3,
-                         max_line_length: int=None):
+                         max_line_length: int=None,
+                         check_valid_links: bool=None):
         """
         :param bullets:
             Character to use for bullets in lists. Can be "-", "*" or "+".
@@ -108,6 +110,9 @@ def create_arguments(filename, file, config_file,
             The number of times the horizontal rule character will be repeated.
         :param max_line_length:
             The maximum line length allowed.
+        :param check_valid_links:
+            Checks if links to headings and files in markdown point to
+            existing things.
         """
         remark_configs_settings = {
             'bullet': bullets,                          # - or *
@@ -136,13 +141,16 @@ def create_arguments(filename, file, config_file,
         # Remove { and } as remark adds them on its own
         settings = config_json[1:-1]
 
-        args = ['--no-color', '--quiet', '--setting', settings]
+        args = [filename, '--no-color', '--quiet', '--setting', settings]
 
         if remark_configs_plugins:
             config_json = json.dumps(remark_configs_plugins)
             plugins = 'lint=' + config_json[1:-1]
             args += ['--use', plugins]
 
+        if check_valid_links:
+            args += ['--use', 'validate-links']
+
         return args
 
     def process_output(self, output, filename, file):

package.json

@@ -19,6 +19,7 @@
     "ramllint": ">=1.2.2 <1.2.4 || >=1.2.5 <1.3.0",
     "remark-cli": "~2",
     "remark-lint": "~5",
+    "remark-validate-links": "~5",
     "standard": "~7",
     "stylelint": "~7",
     "stylint": "~1.5.9",

tests/markdown/MarkdownBearTest.py

@@ -22,6 +22,16 @@
 2. nopqrstuvwxyz
 """
 
+test_file4 = """# Hello
+
+Read more [This link does not exist](#world).
+"""
+
+test_file5 = """# world
+
+Read more [This link exists](#world).
+"""
+
 MarkdownBearTest = verify_local_bear(MarkdownBear,
                                      valid_files=(test_file2,),
                                      invalid_files=(test_file1,))
@@ -55,3 +65,21 @@ def test_invalid_message(self):
                                  'Line must be at most 10 characters'
                                  '  maximum-line-length  remark-lint')
                 self.assertEqual(results[0].severity, RESULT_SEVERITY.NORMAL)
+
+    def test_invalid_link(self):
+        content = test_file4.splitlines()
+        self.section.append(Setting('check_valid_links', True))
+        with prepare_file(content, None) as (file, fname):
+            with execute_bear(self.uut, fname, file) as results:
+                self.assertEqual(results[0].message,
+                                 'Link to unknown heading: `world`'
+                                 '  remark-validate-links  '
+                                 'remark-validate-links')
+                self.assertEqual(results[0].severity, RESULT_SEVERITY.NORMAL)
+
+    def test_valid_link(self):
+        content = test_file5.splitlines()
+        self.section.append(Setting('check_valid_links', True))
+        with prepare_file(content, None) as (file, fname):
+            with execute_bear(self.uut, fname, file) as results:
+                self.assertEqual(results, [])