Add MD042 no-empty-links "No empty links" (fixes #24).

.eslintrc.json

@@ -163,7 +163,7 @@
         "max-len": [2, 80, 4],
         "max-nested-callbacks": [2, 3],
         "max-params": [2, 5],
-        "max-statements": [2, 20],
+        "max-statements": [2, 21],
         "new-cap": 2,
         "new-parens": 2,
         "newline-after-var": 0,

README.md

@@ -81,6 +81,7 @@ playground for learning and exploring.
 * **MD039** *no-space-in-links* - Spaces inside link text
 * **MD040** *fenced-code-language* - Fenced code blocks should have a language specified
 * **MD041** *first-line-h1* - First line in file should be a top level header
+* **MD042** *no-empty-links* - No empty links
 
 See [Rules.md](doc/Rules.md) for more details.
 
@@ -101,7 +102,7 @@ See [Rules.md](doc/Rules.md) for more details.
 * **indentation** - MD005, MD006, MD007, MD027
 * **language** - MD040
 * **line_length** - MD013
-* **links** - MD011, MD034, MD039
+* **links** - MD011, MD034, MD039, MD042
 * **ol** - MD029, MD030, MD032
 * **spaces** - MD018, MD019, MD020, MD021, MD023
 * **ul** - MD004, MD005, MD006, MD007, MD030, MD032

doc/Rules.md

@@ -1004,3 +1004,25 @@ To fix this, add a header to the top of your file:
 
     This is a file with a top level header
     ```
+
+## MD042 - No empty links
+
+Tags: links
+
+Aliases: no-empty-links
+
+This rule is triggered when an empty link is encountered:
+
+    [an empty link]()
+
+To fix the violation, provide a destination for the link:
+
+    [a valid link](https://example.com/)
+
+Empty fragments will trigger this rule:
+
+    [an empty fragment](#)
+
+But non-empty fragments will not:
+
+    [a valid fragment](#fragment)

lib/rules.js

@@ -891,5 +891,21 @@ module.exports = [
         errors.push(1);
       }
     }
+  },
+
+  {
+    "name": "MD042",
+    "desc": "No empty links",
+    "tags": [ "links" ],
+    "aliases": [ "no-empty-links" ],
+    "func": function MD034(params, errors) {
+      forEachInlineChild(params, "link_open", function forToken(token) {
+        token.attrs.forEach(function forAttr(attr) {
+          if (attr[0] === "href" && (!attr[1] || (attr[1] === "#"))) {
+            errors.push(token.lineNumber);
+          }
+        });
+      });
+    }
   }
 ];

test/break-all-the-rules.md

@@ -73,3 +73,5 @@ Code `with ` space {MD038}
 ```
 code fence without language {MD040:73}
 ```
+
+[empty link]() {MD042}

test/empty-links.md

@@ -0,0 +1,31 @@
+# Heading
+
+## Empty links
+
+[text]() {MD042}
+
+[text](<>) {MD042}
+
+[text](#) {MD042}
+
+[text][frag] {MD042}
+
+[frag]: #
+
+## Non-empty links
+
+[text](link)
+
+[text](link "title")
+
+[text](<link>)
+
+[text](#frag)
+
+[text][ref]
+
+[ref]: link
+
+[text]
+
+[text]: link

test/markdownlint-test.js

@@ -543,7 +543,8 @@ module.exports.styleAll = function styleAll(test) {
         "MD038": [ 69 ],
         "MD039": [ 71 ],
         "MD040": [ 73 ],
-        "MD041": [ 1 ]
+        "MD041": [ 1 ],
+        "MD042": [ 77 ]
       }
     };
     test.deepEqual(actualResult, expectedResult, "Undetected issues.");
@@ -580,7 +581,8 @@ module.exports.styleRelaxed = function styleRelaxed(test) {
         "MD031": [ 50 ],
         "MD032": [ 51 ],
         "MD035": [ 61 ],
-        "MD036": [ 65 ]
+        "MD036": [ 65 ],
+        "MD042": [ 77 ]
       }
     };
     test.deepEqual(actualResult, expectedResult, "Undetected issues.");
@@ -731,7 +733,7 @@ module.exports.missingStringValue = function missingStringValue(test) {
 };
 
 module.exports.ruleNamesUpperCase = function ruleNamesUpperCase(test) {
-  test.expect(37);
+  test.expect(38);
   rules.forEach(function forRule(rule) {
     test.equal(rule.name, rule.name.toUpperCase(), "Rule name not upper-case.");
   });
@@ -739,7 +741,7 @@ module.exports.ruleNamesUpperCase = function ruleNamesUpperCase(test) {
 };
 
 module.exports.uniqueAliases = function uniqueAliases(test) {
-  test.expect(74);
+  test.expect(76);
   var tags = [];
   rules.forEach(function forRule(rule) {
     Array.prototype.push.apply(tags, rule.tags);
@@ -756,7 +758,7 @@ module.exports.uniqueAliases = function uniqueAliases(test) {
 };
 
 module.exports.readme = function readme(test) {
-  test.expect(97);
+  test.expect(99);
   var tagToRules = {};
   rules.forEach(function forRule(rule) {
     rule.tags.forEach(function forTag(tag) {
@@ -817,7 +819,7 @@ module.exports.readme = function readme(test) {
 };
 
 module.exports.doc = function doc(test) {
-  test.expect(274);
+  test.expect(281);
   fs.readFile("doc/Rules.md", shared.utf8Encoding,
     function readFile(err, contents) {
       test.ifError(err);
@@ -848,14 +850,16 @@ module.exports.doc = function doc(test) {
             ruleHasTags = ruleHasAliases = false;
             test.ok(rule,
               "Missing rule implementation for " + token.content + ".");
-            test.equal(token.content, rule.name + " - " + rule.desc,
-              "Rule mismatch.");
-            ruleUsesParams = rule.func.toString()
-              .match(/params\.options\.[_a-z]*/gi);
-            if (ruleUsesParams) {
-              ruleUsesParams = ruleUsesParams.map(function forUse(use) {
-                return use.split(".").pop();
-              });
+            if (rule) {
+              test.equal(token.content, rule.name + " - " + rule.desc,
+                "Rule mismatch.");
+              ruleUsesParams = rule.func.toString()
+                .match(/params\.options\.[_a-z]*/gi);
+              if (ruleUsesParams) {
+                ruleUsesParams = ruleUsesParams.map(function forUse(use) {
+                  return use.split(".").pop();
+                });
+              }
             }
           } else if (/^Tags: /.test(token.content) && rule) {
             test.deepEqual(token.content.split(tagAliasParameterRe).slice(1),
@@ -882,7 +886,9 @@ module.exports.doc = function doc(test) {
       var ruleLeft = rulesLeft.shift();
       test.ok(!ruleLeft,
         "Missing rule documentation for " + (ruleLeft || {}).name + ".");
-      testTagsAliasesParams();
+      if (rule) {
+        testTagsAliasesParams();
+      }
       test.done();
     });
 };