Add support for checking images, image references

Closes GH-29.
Closes GH-30.

Reviewed-by: Rob Hilgefort <rob.hilgefort.me>
Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>

index.js

@@ -270,26 +270,26 @@ function gatherReferences(file, tree, info, fileSet) {
 
   lines = info && info.type in lineLinks ? lineLinks[info.type] : false
 
-  visit(tree, ['link', 'linkReference'], onlink)
+  visit(tree, ['link', 'image', 'linkReference', 'imageReference'], onresource)
 
   return cache
 
-  // Handle new links.
-  function onlink(node) {
+  // Handle resources.
+  function onresource(node) {
     var link = node.url
     var definition
     var index
     var uri
     var pathname
     var hash
 
-    // Handle link-references.
+    // Handle references.
     if (node.identifier) {
       definition = getDefinition(node.identifier)
       link = definition && definition.url
     }
 
-    // Ignore definitions without link.
+    // Ignore definitions without url.
     if (!link) {
       return
     }

readme.md

@@ -7,8 +7,8 @@
 [![Sponsors][sponsors-badge]][collective]
 [![Backers][backers-badge]][collective]
 
-[**remark**][remark] plugin to validate if internal links to headings and files
-in markdown point to existing things.
+[**remark**][remark] plugin to validate if internal links or images to headings
+and files in markdown point to existing things.
 It does not check external URLs (see [`remark-lint-no-dead-urls`][no-dead-urls]
 for that).
 
@@ -20,7 +20,7 @@ In addition, when I link to a heading in another document
 (`examples/foo.md#hello`), if this file exists but the heading does not,
 or if the file does not exist, this plugin will also warn.
 
-Linking to other files, such as `LICENSE` or `index.js` (when they exist)
+Linking to other files, such as `license` or `index.js` (when they exist)
 is fine.
 
 ## Table of Contents

test/fixtures/images.md

@@ -0,0 +1,35 @@
+# Image references
+
+<!-- Valid: -->
+
+Relative ![image](./examples/image.jpg)
+
+No `./` in ![image](examples/image.jpg)
+
+Absolute ![image](https://github.com/wooorm/test/blob/master/examples/image.jpg)
+
+Relative ![image reference][rel]
+
+Absolute ![image reference][abs]
+
+<!-- Invalid: -->
+
+Relative ![missing image](./examples/missing.jpg)
+
+No `./` in ![image](examples/missing.jpg)
+
+Absolute ![missing image](https://github.com/wooorm/test/blob/master/examples/missing.jpg)
+
+Relative ![missing image reference][rel-missing]
+
+Absolute ![missing image reference][abs-missing]
+
+<!-- Definitions: -->
+
+[rel]: ./examples/image.jpg
+
+[abs]: https://github.com/wooorm/test/blob/master/examples/image.jpg
+
+[rel-missing]: ./examples/missing.jpg
+
+[abs-missing]: https://github.com/wooorm/test/blob/master/examples/missing.jpg

test/index.js

@@ -495,5 +495,34 @@ test('remark-validate-links', function(t) {
     }, st.error)
   })
 
+  t.test('should check images', function(st) {
+    st.plan(1)
+
+    execa(bin, [
+      '--no-config',
+      '--no-ignore',
+      '--use',
+      '../..=repository:"wooorm/test"',
+      '--use',
+      '../sort',
+      'images.md'
+    ]).then(function(result) {
+      st.equal(
+        strip(result.stderr),
+        [
+          'images.md',
+          '  17:10-17:50  warning  Link to unknown file: `examples/missing.jpg`  missing-file  remark-validate-links',
+          '  19:12-19:42  warning  Link to unknown file: `examples/missing.jpg`  missing-file  remark-validate-links',
+          '  21:10-21:91  warning  Link to unknown file: `examples/missing.jpg`  missing-file  remark-validate-links',
+          '  23:10-23:49  warning  Link to unknown file: `examples/missing.jpg`  missing-file  remark-validate-links',
+          '  25:10-25:49  warning  Link to unknown file: `examples/missing.jpg`  missing-file  remark-validate-links',
+          '',
+          '⚠ 5 warnings'
+        ].join('\n'),
+        'should report'
+      )
+    }, st.error)
+  })
+
   t.end()
 })