Implement rule to flag use of alert (fixes #10)

config/eslint.json

@@ -1,6 +1,7 @@
 {
     "rules": {
 
+        "no-alert": 1,
         "no-arg": 1,
         "no-console": 1,
         "no-debugger": 1,

lib/rules.js

@@ -13,6 +13,12 @@
 var fs = require("fs"),
     path = require("path");
 
+//------------------------------------------------------------------------------
+// Constants
+//------------------------------------------------------------------------------
+
+var JS_EXT = ".js";
+
 //------------------------------------------------------------------------------
 // Privates
 //------------------------------------------------------------------------------
@@ -26,12 +32,12 @@ var rules = {};
 exports.load = function(directory) {
 
     try {
-        var fullPath = path.join(__dirname, directory),
+        var fullPath = path.resolve(process.cwd(), directory),
             files = fs.readdirSync(fullPath);
 
         files.forEach(function(file) {
-            if (path.extname(file) === ".js") {
-                var ruleId = file.replace(".js", "");
+            if (path.extname(file) === JS_EXT) {
+                var ruleId = file.replace(JS_EXT, "");
                 rules[ruleId] = require(path.join(fullPath, ruleId));
             }
         });
@@ -50,4 +56,5 @@ exports.get = function(ruleId) {
 // Initialization
 //------------------------------------------------------------------------------
 
-exports.load("./rules");
+// loads built-in rules
+exports.load(path.join(__dirname, "./rules"));

lib/rules/no-alert.js

@@ -0,0 +1,51 @@
+/**
+ * @fileoverview Rule to flag use of alert, confirm, prompt
+ * @author Nicholas C. Zakas
+ */
+
+/*jshint node:true*/
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+function matchProhibited(name) {
+    return name.match(/^(alert|confirm|prompt)$/);
+}
+
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    return {
+
+        "CallExpression": function(node) {
+
+            var result;
+
+            // without window.
+            if (node.callee.type === "Identifier") {
+
+                result = matchProhibited(node.callee.name);
+
+                if (result) {
+                    context.report(node, "Unexpected " + result[1] + ".");
+                }
+
+            } else if (node.callee.type === "MemberExpression") {
+
+                result = matchProhibited(node.callee.property.name);
+
+                if (result && node.callee.object.name === "window") {
+                    context.report(node, "Unexpected " + result[1] + ".");
+                }
+
+            }
+
+        }
+    };
+
+};

tests/lib/rules/no-alert.js

@@ -0,0 +1,179 @@
+/**
+ * @fileoverview Tests for no-alert rule.
+ * @author Nicholas C. Zakas
+ */
+
+/*jshint node:true*/
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+var vows = require("vows"),
+    assert = require("assert"),
+    sinon = require("sinon"),
+    eslint = require("../../../lib/eslint");
+
+//------------------------------------------------------------------------------
+// Constants
+//------------------------------------------------------------------------------
+
+var RULE_ID = "no-alert";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+vows.describe(RULE_ID).addBatch({
+
+    "when evaluating 'alert(foo)'": {
+
+        topic: "alert(foo)",
+
+        "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, "Unexpected alert.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.name, "alert");
+        }
+    },
+
+    "when evaluating 'window.alert(foo)'": {
+
+        topic: "window.alert(foo)",
+
+        "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, "Unexpected alert.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.property.name, "alert");
+        }
+    },
+
+    "when evaluating 'confirm(foo)'": {
+
+        topic: "confirm(foo)",
+
+        "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, "Unexpected confirm.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.name, "confirm");
+        }
+    },
+
+    "when evaluating 'window.confirm(foo)'": {
+
+        topic: "window.confirm(foo)",
+
+        "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, "Unexpected confirm.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.property.name, "confirm");
+        }
+    },
+
+    "when evaluating 'prompt(foo)'": {
+
+        topic: "prompt(foo)",
+
+        "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, "Unexpected prompt.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.name, "prompt");
+        }
+    },
+
+    "when evaluating 'window.prompt(foo)'": {
+
+        topic: "window.prompt(foo)",
+
+        "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, "Unexpected prompt.");
+            assert.include(messages[0].node.type, "CallExpression");
+            assert.include(messages[0].node.callee.property.name, "prompt");
+        }
+    },
+
+    "when evaluating 'foo.alert(foo)'": {
+
+        topic: "foo.alert(foo)",
+
+        "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 'foo.confirm(foo)'": {
+
+        topic: "foo.confirm(foo)",
+
+        "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 'foo.prompt(foo)'": {
+
+        topic: "foo.prompt(foo)",
+
+        "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);