From 02f93c318cd9d6672c3e9020464de3362441e0ad Mon Sep 17 00:00:00 2001
From: Robert Jackson <robert.w.jackson@me.com>
Date: Wed, 4 Nov 2015 11:57:15 -0500
Subject: [PATCH] Add rule for const outside of module scope.

Good:

```
const FOO = 'FOO';
export const BAR = 'BAR';
```

Bad:

```
function derp() {
  const FOO = 'FOO';
}

if (false) {
  const BLAH = 'BLAH';
}
```

---

I did not add configuration for this rule in the default preset (but I
can if we want it)...
---
 lib/jscsrc.json                               |  1 +
 .../disallow-const-outside-module-scope.js    | 38 +++++++++++++++++++
 .../bad/inside-function.js                    |  3 ++
 .../bad/inside-if.js                          |  3 ++
 .../good/example.js                           |  6 +++
 5 files changed, 51 insertions(+)
 create mode 100644 lib/rules/disallow-const-outside-module-scope.js
 create mode 100644 tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-function.js
 create mode 100644 tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-if.js
 create mode 100644 tests/fixtures/rules/disallow-const-outside-module-scope/good/example.js

diff --git a/lib/jscsrc.json b/lib/jscsrc.json
index 0a6af07..abb1fee 100644
--- a/lib/jscsrc.json
+++ b/lib/jscsrc.json
@@ -6,6 +6,7 @@
     "./rules/*.js"
   ],
 
+  "disallowConstOutsideModuleScope": true,
   "disallowEmptyBlocks": true,
   "disallowKeywordsOnNewLine": ["else"],
   "disallowMultipleLineBreaks": true,
diff --git a/lib/rules/disallow-const-outside-module-scope.js b/lib/rules/disallow-const-outside-module-scope.js
new file mode 100644
index 0000000..32c2045
--- /dev/null
+++ b/lib/rules/disallow-const-outside-module-scope.js
@@ -0,0 +1,38 @@
+var assert = require('assert');
+
+module.exports = function() { };
+
+module.exports.prototype = {
+  configure: function(option) {
+    assert(option === true, this.getOptionName() + ' requires a true value');
+  },
+
+  getOptionName: function() {
+    return 'disallowConstOutsideModuleScope';
+  },
+
+  check: function(file, errors) {
+    file.iterateNodesByType('VariableDeclaration', function(node) {
+      if (node.parentNode.type === 'Program') {
+        // declaration is in root of module
+        return;
+      }
+
+      if (node.parentNode.type === 'ExportNamedDeclaration' && node.parentNode.parentNode.type === 'Program') {
+        // declaration is a `export const foo = 'asdf'` in root of the module
+        return;
+      }
+
+      for (var i = 0; i < node.declarations.length; i++) {
+        var thisDeclaration = node.declarations[i];
+
+        if (thisDeclaration.parentNode.kind === 'const') {
+          errors.add(
+            '`const` should only be used in module scope (not inside functions/blocks).',
+            node.loc.start
+          );
+        }
+      }
+    });
+  }
+};
diff --git a/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-function.js b/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-function.js
new file mode 100644
index 0000000..7f3ad39
--- /dev/null
+++ b/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-function.js
@@ -0,0 +1,3 @@
+function something() {
+  const foo = 'bar';
+}
diff --git a/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-if.js b/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-if.js
new file mode 100644
index 0000000..965f99a
--- /dev/null
+++ b/tests/fixtures/rules/disallow-const-outside-module-scope/bad/inside-if.js
@@ -0,0 +1,3 @@
+if (true) {
+  const foo = 'bar';
+}
diff --git a/tests/fixtures/rules/disallow-const-outside-module-scope/good/example.js b/tests/fixtures/rules/disallow-const-outside-module-scope/good/example.js
new file mode 100644
index 0000000..d370a64
--- /dev/null
+++ b/tests/fixtures/rules/disallow-const-outside-module-scope/good/example.js
@@ -0,0 +1,6 @@
+const foo = 'blah';
+export const bar = 'derp';
+
+function something() {
+  let hey = 'you!';
+}