tools: add eslint rule for inspector checking

The motivation for this commit is to pick up early on missing checks for
inspector support (when Node is built --without-inspector).

test/.eslintrc.yaml

@@ -11,5 +11,6 @@ rules:
   prefer-assert-methods: error
   prefer-common-mustnotcall: error
   crypto-check: error
+  inspector-check: error
   ## common module is mandatory in tests
   required-modules: [error, common]

tools/eslint-rules/inspector-check.js

@@ -0,0 +1,43 @@
+/**
+ * @fileoverview Check that common.skipIfInspectorDisabled is used if
+ *               the inspector module is required.
+ * @author Daniel Bevenius <daniel.bevenius@gmail.com>
+ */
+'use strict';
+
+const utils = require('./rules-utils.js');
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+const msg = 'Please add a skipIfInspectorDisabled() call to allow this ' +
+            'test to be skippped when Node is built \'--without-inspector\'.';
+
+module.exports = function(context) {
+  var usesInspector = false;
+  var hasInspectorCheck = false;
+
+  function testInspectorUsage(context, node) {
+    if (utils.isRequired(node, ['inspector'])) {
+      usesInspector = true;
+    }
+  }
+
+  function checkMemberExpression(context, node) {
+    if (utils.usesCommonProperty(node, ['skipIfInspectorDisabled'])) {
+      hasInspectorCheck = true;
+    }
+  }
+
+  function reportIfMissing(context, node) {
+    if (usesInspector && !hasInspectorCheck) {
+      context.report(node, msg);
+    }
+  }
+
+  return {
+    'CallExpression': (node) => testInspectorUsage(context, node),
+    'MemberExpression': (node) => checkMemberExpression(context, node),
+    'Program:exit': (node) => reportIfMissing(context, node)
+  };
+};