From 6fdcc932bc1bb557c39e49e352c3676b80220755 Mon Sep 17 00:00:00 2001
From: Benjamin Stepp <me@benstepp.com>
Date: Tue, 26 Jul 2016 23:56:50 -0500
Subject: [PATCH] Add new no-children-prop rule (Fixes #720)

Prevents children being passed as props. Children should be actual
children.

---

* Add Component to tests for no-children-prop
* Add note in docs about recommended behavior
* Change syntax in docs for no-children-prop to jsx

---

* Clarify that multiple arguments may be passed as children to
React.createElement
* Reorganize tests to show JSX with createElement counterpart immediately
following.
* Added test cases with a non-children property
* Added test cases with multiple children
---
 README.md                           |   1 +
 docs/rules/no-children-prop.md      |  36 +++++
 index.js                            |   3 +-
 lib/rules/no-children-prop.js       |  65 ++++++++
 tests/lib/rules/no-children-prop.js | 237 ++++++++++++++++++++++++++++
 5 files changed, 341 insertions(+), 1 deletion(-)
 create mode 100644 docs/rules/no-children-prop.md
 create mode 100644 lib/rules/no-children-prop.js
 create mode 100644 tests/lib/rules/no-children-prop.js

diff --git a/README.md b/README.md
index fb08b1cb6a..3bb37e6237 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,7 @@ Finally, enable all of the rules that you would like to use.  Use [our preset](#
 
 * [react/display-name](docs/rules/display-name.md): Prevent missing `displayName` in a React component definition
 * [react/forbid-prop-types](docs/rules/forbid-prop-types.md): Forbid certain propTypes
+* [react/no-children-prop](docs/rules/no-children-prop.md): Prevent passing children as props
 * [react/no-danger](docs/rules/no-danger.md): Prevent usage of dangerous JSX properties
 * [react/no-deprecated](docs/rules/no-deprecated.md): Prevent usage of deprecated methods
 * [react/no-did-mount-set-state](docs/rules/no-did-mount-set-state.md): Prevent usage of `setState` in `componentDidMount`
diff --git a/docs/rules/no-children-prop.md b/docs/rules/no-children-prop.md
new file mode 100644
index 0000000000..e49c7d8715
--- /dev/null
+++ b/docs/rules/no-children-prop.md
@@ -0,0 +1,36 @@
+# Prevent passing of children as props (no-children-prop)
+
+Children should always be actual children, not passed in as a prop.
+
+When using JSX, the children should be nested between the opening and closing
+tags. When not using JSX, the children should be passed as additional
+arguments to `React.createElement`.
+
+## Rule Details
+
+The following patterns are considered warnings:
+
+```jsx
+<div children='Children' />
+
+<MyComponent children={<AnotherComponent />} />
+<MyComponent children={['Child 1', 'Child 2']} />
+
+React.createElement("div", { children: 'Children' })
+```
+
+The following patterns are not considered warnings:
+
+```jsx
+<div>Children</div>
+
+<MyComponent>Children</MyComponent>
+
+<MyComponent>
+  <span>Child 1</span>
+  <span>Child 2</span>
+</MyComponent>
+
+React.createElement("div", {}, 'Children')
+React.createElement("div", 'Child 1', 'Child 2')
+```
diff --git a/index.js b/index.js
index a28494f79e..effbfa0a21 100644
--- a/index.js
+++ b/index.js
@@ -50,7 +50,8 @@ var rules = {
   'jsx-no-target-blank': require('./lib/rules/jsx-no-target-blank'),
   'jsx-filename-extension': require('./lib/rules/jsx-filename-extension'),
   'require-optimization': require('./lib/rules/require-optimization'),
-  'no-find-dom-node': require('./lib/rules/no-find-dom-node')
+  'no-find-dom-node': require('./lib/rules/no-find-dom-node'),
+  'no-children-prop': require('./lib/rules/no-children-prop')
 };
 
 var ruleNames = Object.keys(rules);
diff --git a/lib/rules/no-children-prop.js b/lib/rules/no-children-prop.js
new file mode 100644
index 0000000000..efead3b2f7
--- /dev/null
+++ b/lib/rules/no-children-prop.js
@@ -0,0 +1,65 @@
+/**
+ * @fileoverview Prevent passing of children as props
+ * @author Benjamin Stepp
+ */
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * Checks if the node is a createElement call with a props literal.
+ * @param {ASTNode} node - The AST node being checked.
+ * @returns {Boolean} - True if node is a createElement call with a props
+ * object literal, False if not.
+*/
+function isCreateElementWithProps(node) {
+  return node.callee
+    && node.callee.type === 'MemberExpression'
+    && node.callee.property.name === 'createElement'
+    && node.arguments.length > 1
+    && node.arguments[1].type === 'ObjectExpression';
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    docs: {},
+    schema: []
+  },
+  create: function(context) {
+    return {
+      JSXAttribute: function(node) {
+        if (node.name.name !== 'children') {
+          return;
+        }
+
+        context.report({
+          node: node,
+          message: 'Do not pass children as props. Instead, nest children between the opening and closing tags.'
+        });
+      },
+      CallExpression: function(node) {
+        if (!isCreateElementWithProps(node)) {
+          return;
+        }
+
+        var props = node.arguments[1].properties;
+        var childrenProp = props.find(function(prop) {
+          return prop.key.name === 'children';
+        });
+
+        if (childrenProp) {
+          context.report({
+            node: node,
+            message: 'Do not pass children as props. Instead, pass them as additional arguments to React.createElement.'
+          });
+        }
+      }
+    };
+  }
+};
diff --git a/tests/lib/rules/no-children-prop.js b/tests/lib/rules/no-children-prop.js
new file mode 100644
index 0000000000..d0073dc0f2
--- /dev/null
+++ b/tests/lib/rules/no-children-prop.js
@@ -0,0 +1,237 @@
+/**
+ * @fileoverview Tests for no-children-prop
+ * @author Benjamin Stepp
+ */
+
+'use strict';
+
+// -----------------------------------------------------------------------------
+// Requirements
+// -----------------------------------------------------------------------------
+
+var rule = require('../../../lib/rules/no-children-prop');
+var RuleTester = require('eslint').RuleTester;
+
+var parserOptions = {
+  ecmaVersion: 6,
+  ecmaFeatures: {
+    jsx: true
+  }
+};
+
+var JSX_ERROR = 'Do not pass children as props. Instead, nest children between \
+the opening and closing tags.';
+var CREATE_ELEMENT_ERROR = 'Do not pass children as props. Instead, pass them \
+as additional arguments to React.createElement.';
+
+// -----------------------------------------------------------------------------
+// Tests
+// -----------------------------------------------------------------------------
+
+var ruleTester = new RuleTester();
+ruleTester.run('no-children-prop', rule, {
+  valid: [
+    {
+      code: '<div />;',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div></div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {});',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", undefined);',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div className="class-name"></div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {className: "class-name"});',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div>Children</div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {}, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", undefined, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div className="class-name">Children</div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {className: "class-name"}, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div><div /></div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {}, React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", undefined, React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div><div /><div /></div>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", React.createElement("div"), React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {}, React.createElement("div"), React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", undefined, React.createElement("div"), React.createElement("div"));',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", [React.createElement("div"), React.createElement("div")]);',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {}, [React.createElement("div"), React.createElement("div")]);',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", undefined, [React.createElement("div"), React.createElement("div")]);',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent />',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent);',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {});',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, undefined);',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent>Children</MyComponent>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {}, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, undefined, "Children");',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent className="class-name"></MyComponent>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {className: "class-name"});',
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent className="class-name">Children</MyComponent>;',
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {className: "class-name"}, "Children");',
+      parserOptions: parserOptions
+    }
+  ],
+  invalid: [
+    {
+      code: '<div children="Children" />;',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div children={<div />} />;',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div children={[<div />, <div />]} />;',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: '<div children="Children">Children</div>;',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {children: "Children"});',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {children: "Children"}, "Children");',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {children: React.createElement("div")});',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement("div", {children: [React.createElement("div"), React.createElement("div")]});',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent children="Children" />',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {children: "Children"});',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: '<MyComponent className="class-name" children="Children" />;',
+      errors: [{message: JSX_ERROR}],
+      parserOptions: parserOptions
+    },
+    {
+      code: 'React.createElement(MyComponent, {children: "Children", className: "class-name"});',
+      errors: [{message: CREATE_ELEMENT_ERROR}],
+      parserOptions: parserOptions
+    }
+  ]
+});