Rule: count-spaces for multiple spaces in regular expressions

conf/eslint.json

@@ -43,6 +43,7 @@
         "quotes": [1, "double"],
         "max-params": [0, 3],
         "max-statements": [0, 10],
+        "count-spaces": 1,
         "complexity": [0, 11]
 
     }

lib/rules/count-spaces.js

@@ -0,0 +1,31 @@
+/**
+ * @fileoverview Rule to count multiple spaces in regular expressions
+ * @author Matt DuVall <http://www.mattduvall.com/>
+ */
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    return {
+
+        "Literal": function(node) {
+            var token = context.getTokens(node)[0],
+                nodeType = token.type,
+                nodeValue = token.value,
+                multipleSpacesRegex = /( {2,})+?/,
+                regexResults;
+
+            if (nodeType === "RegularExpression") {
+                regexResults = multipleSpacesRegex.exec(nodeValue);
+
+                if (regexResults !== null) {
+                    context.report(node, "Spaces are hard to count. Use {" + regexResults[0].length + "}.");
+                }
+            }
+        }
+    };
+
+};

tests/lib/rules/count-spaces.js

@@ -0,0 +1,75 @@
+/**
+ * @fileoverview Tests for the count-spaces rule
+ * @author Matt DuVall <http://www.mattduvall.com/>
+ */
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+var vows = require("vows"),
+    assert = require("assert"),
+    eslint = require("../../../lib/eslint");
+
+//------------------------------------------------------------------------------
+// Constants
+//------------------------------------------------------------------------------
+
+var RULE_ID = "count-spaces";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+vows.describe(RULE_ID).addBatch({
+
+    "when evaluating a regular expression with multiple spaces": {
+
+        topic: "var foo = /bar    baz/;",
+
+        "should report a violation": function(topic) {
+
+            var config = { rules: {} };
+            config.rules[RULE_ID] = 1;
+
+            var messages = eslint.verify(topic, config);
+
+            assert.equal(messages.length, 1);
+            assert.equal(messages[0].ruleId, RULE_ID);
+            assert.equal(messages[0].message, "Spaces are hard to count. Use {4}.");
+            assert.include(messages[0].node.type, "Literal");
+        }
+    },
+
+    "when evaluating a regular expression with the reptition operator": {
+
+        topic: "var foo = /bar {3}baz/;",
+
+        "should not report a violation": function(topic) {
+
+            var config = { rules: {} };
+            config.rules[RULE_ID] = 1;
+
+            var messages = eslint.verify(topic, config);
+
+            assert.equal(messages.length, 0);
+        }
+    },
+
+    "when evaluating a regular expression with multiple non-space whitespace": {
+
+        topic: "var foo = /bar\t\t\tbaz/;",
+
+        "should not report a violation": function(topic) {
+
+            var config = { rules: {} };
+            config.rules[RULE_ID] = 1;
+
+            var messages = eslint.verify(topic, config);
+
+            assert.equal(messages.length, 0);
+        }
+    }
+
+
+}).export(module);