tools: lint rule for assert.fail()

`assert.fail()` is often mistakenly used with a single argument even in
Node.js core. (See fixes to previous instances in
b7f4b1b,
28e9a02. and
676e618.)
This commit adds a linting rule to identify instances of this issue.
PR-URL: #6261
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: Trott

.eslintrc

@@ -85,6 +85,7 @@ rules:
  prefer-const: 2
 
  # Custom rules in tools/eslint-rules
+ assert-fail-single-argument: 2
  new-with-error: [2, "Error", "RangeError", "TypeError", "SyntaxError", "ReferenceError"]
  align-multiline-assignment: 2
 

tools/eslint-rules/assert-fail-single-argument.js

@@ -0,0 +1,30 @@
+/**
+ * @fileoverview Prohibit use of a single argument only in `assert.fail()`. It
+ * is almost always an error.
+ * @author Rich Trott
+ */
+'use strict';
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+constmsg='assert.fail() message should be third argument';
+
+functionisAssert(node){
+returnnode.callee.object&&node.callee.object.name==='assert';
+}
+
+functionisFail(node){
+returnnode.callee.property&&node.callee.property.name==='fail';
+}
+
+module.exports=function(context){
+return{
+'CallExpression': function(node){
+if(isAssert(node)&&isFail(node)&&node.arguments.length===1){
+context.report(node,msg);
+}
+}
+};
+};