Add MD020, MD021 with tests.

lib/rules.js

@@ -270,7 +270,7 @@ module.exports = [
     "desc": "No space after hash on atx style header",
     "func": function MD018(params, errors) {
       params.lines.forEach(function forLine(line, lineIndex) {
-        if (/^#+[^#\s]/.test(line)) {
+        if (/^#+[^#\s]/.test(line) && !/#$/.test(line)) {
           errors.push(lineIndex + 1);
         }
       });
@@ -291,6 +291,33 @@ module.exports = [
     }
   },
 
+  {
+    "name": "MD020",
+    "desc": "No space inside hashes on closed atx style header",
+    "func": function MD020(params, errors) {
+      params.lines.forEach(function forLine(line, lineIndex) {
+        if (/^#+[^#]*[^\\]#+$/.test(line) &&
+            (/^#+[^#\s]/.test(line) || /[^#\s]#+$/.test(line))) {
+          errors.push(lineIndex + 1);
+        }
+      });
+    }
+  },
+
+  {
+    "name": "MD021",
+    "desc": "Multiple spaces inside hashes on closed atx style header",
+    "func": function MD021(params, errors) {
+      filterTokens(params.tokens, "heading_open")
+        .forEach(function forToken(token) {
+          if ((headingStyleFor(token) === "atx_closed") &&
+              (/^#+\s\s/.test(token.line) || /\s\s#+$/.test(token.line))) {
+            errors.push(token.lineNumber);
+          }
+        });
+    }
+  },
+
   {
     "name": "MD028",
     "desc": "Blank line inside blockquote",

test/atx_closed_header_spacing.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD002": false
+}

test/atx_closed_header_spacing.md

@@ -0,0 +1,17 @@
+#Header 1 {MD020} #
+
+## Header 2 {MD020}##
+
+##Header 3 {MD020}##
+
+##  Header 4 {MD021} ##
+
+## Header 5 {MD021}  ##
+
+##  Header 6 {MD021}  ##
+
+##   Header 7 {MD021}   ##
+
+## Header 8 \#
+
+## Header 9  \#