[New] Symmetric useState hook variable names

Ensure two symmetrically-named variables are destructured from useState hook calls

README.md

@@ -115,6 +115,7 @@ Enable the rules that you would like to use.
 |  |  | [react/forbid-foreign-prop-types](docs/rules/forbid-foreign-prop-types.md) | Forbid using another component's propTypes |
 |  |  | [react/forbid-prop-types](docs/rules/forbid-prop-types.md) | Forbid certain propTypes |
 |  | 🔧 | [react/function-component-definition](docs/rules/function-component-definition.md) | Standardize the way function component get defined |
+|  | 🔧 | [react/hook-use-state](docs/rules/hook-use-state.md) | Ensure symmetric naming of useState hook value and setter variables |
 |  |  | [react/no-access-state-in-setstate](docs/rules/no-access-state-in-setstate.md) | Reports when this.state is accessed within setState |
 |  |  | [react/no-adjacent-inline-elements](docs/rules/no-adjacent-inline-elements.md) | Prevent adjacent inline elements not separated by whitespace. |
 |  |  | [react/no-array-index-key](docs/rules/no-array-index-key.md) | Prevent usage of Array index in keys |

docs/rules/hook-use-state.md

@@ -0,0 +1,23 @@
+# Ensure destructuring and symmetric naming of useState hook value and setter variables (react/hook-use-state)
+
+**Fixable:** In some cases, this rule is automatically fixable using the `--fix` flag on the command line.
+
+## Rule Details
+
+This rule checks whether the value and setter variables destructured from a `React.useState()` call are named symmetrically.
+
+Examples of **incorrect** code for this rule:
+
+```js
+const useStateResult = React.useState();
+```
+
+```js
+const [color, updateColor] = React.useState();
+```
+
+Examples of **correct** code for this rule:
+
+```js
+const [color, setColor] = React.useState();
+```

index.js

@@ -16,6 +16,7 @@ const allRules = {
   'forbid-foreign-prop-types': require('./lib/rules/forbid-foreign-prop-types'),
   'forbid-prop-types': require('./lib/rules/forbid-prop-types'),
   'function-component-definition': require('./lib/rules/function-component-definition'),
+  'hook-use-state': require('./lib/rules/hook-use-state'),
   'jsx-boolean-value': require('./lib/rules/jsx-boolean-value'),
   'jsx-child-element-spacing': require('./lib/rules/jsx-child-element-spacing'),
   'jsx-closing-bracket-location': require('./lib/rules/jsx-closing-bracket-location'),

lib/rules/hook-use-state.js

@@ -0,0 +1,101 @@
+/**
+ * @fileoverview Ensure symmetric naming of useState hook value and setter variables
+ * @author Duncan Beevers
+ */
+
+'use strict';
+
+const docsUrl = require('../util/docsUrl');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+const USE_STATE_ERROR_MESSAGE = 'useStateErrorMessage';
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'Ensure symmetric naming of useState hook value and setter variables',
+      category: 'Best Practices',
+      recommended: false,
+      url: docsUrl('hook-use-state')
+    },
+    fixable: 'code',
+    messages: {
+      [USE_STATE_ERROR_MESSAGE]: 'setState call is not destructured into value + setter pair'
+    },
+    schema: [{
+      type: 'object',
+      additionalProperties: false
+    }]
+  },
+
+  create(context) {
+    return {
+      CallExpression(node) {
+        const isReactUseStateCall = (
+          node.callee.type === 'MemberExpression'
+          && node.callee.object.type === 'Identifier'
+          && node.callee.object.name === 'React'
+          && node.callee.property.type === 'Identifier'
+          && node.callee.property.name === 'useState'
+        );
+
+        const isUseStateCall = (
+          node.callee.type === 'Identifier'
+          && node.callee.name === 'useState'
+        );
+
+        // Ignore unless this is a useState() or React.useState() call.
+        if (!isReactUseStateCall && !isUseStateCall) {
+          return;
+        }
+
+        const isDestructuringDeclarator = (
+          node.parent.type === 'VariableDeclarator'
+          && node.parent.id.type === 'ArrayPattern'
+        );
+
+        if (!isDestructuringDeclarator) {
+          context.report({node, messageId: USE_STATE_ERROR_MESSAGE});
+          return;
+        }
+
+        const variableNodes = node.parent.id.elements;
+        const valueVariable = variableNodes[0];
+        const setterVariable = variableNodes[1];
+
+        const valueVariableName = valueVariable
+          ? valueVariable.name
+          : undefined;
+
+        const setterVariableName = setterVariable
+          ? setterVariable.name
+          : undefined;
+
+        const expectedSetterVariableName = valueVariableName ? (
+          `set${
+            valueVariableName.charAt(0).toUpperCase()
+          }${valueVariableName.slice(1)}`
+        ) : undefined;
+
+        if (
+          !valueVariable
+          || !setterVariable
+          || setterVariableName !== expectedSetterVariableName
+          || variableNodes.length !== 2
+        ) {
+          context.report({
+            node: node.parent.id,
+            messageId: USE_STATE_ERROR_MESSAGE,
+            fix: valueVariableName ? (fixer) => fixer.replaceTextRange(
+              [node.parent.id.range[0], node.parent.id.range[1]],
+              `[${valueVariableName}, ${expectedSetterVariableName}]`
+            ) : undefined
+          });
+        }
+      }
+    };
+  }
+};

tests/lib/rules/hook-use-state.js

@@ -0,0 +1,172 @@
+/**
+ * @fileoverview Ensure symmetric naming of setState hook value and setter variables
+ * @author Duncan Beevers
+ */
+
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const RuleTester = require('eslint').RuleTester;
+const rule = require('../../../lib/rules/hook-use-state');
+const parsers = require('../../helpers/parsers');
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2018,
+    sourceType: 'module'
+  }
+});
+
+const tests = {
+  valid: [
+    {
+      code: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [color, setColor] = useState(\'#ffffff\')'
+    },
+    {
+      code: 'const [color, setColor] = React.useState()'
+    },
+    {
+      code: 'const [color1, setColor1] = useState()'
+    },
+    {
+      code: 'const [color, setColor] = useState<string>()',
+      parser: parsers.TYPESCRIPT_ESLINT
+    },
+    {
+      code: 'const [color, setColor] = useState<string>(\'#ffffff\')',
+      parser: parsers.TYPESCRIPT_ESLINT
+    }
+  ].concat(parsers.TS([
+    {
+      code: 'const [color, setColor] = useState<string>()',
+      parser: parsers['@TYPESCRIPT_ESLINT']
+    },
+    {
+      code: 'const [color, setColor] = useState<string>(\'#ffffff\')',
+      parser: parsers['@TYPESCRIPT_ESLINT']
+    }
+  ])
+  ),
+  invalid: [
+    {
+      code: 'useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const result = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const result = React.useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [, , extra1] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [, setColor] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const { color } = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [, , , ,] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [color] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [color, , extra1] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [color, setColor, extra1, extra2, extra3] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [, makeColor] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }]
+    },
+    {
+      code: 'const [color, setFlavor, extraneous] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [color, setFlavor] = useState()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState()'
+    },
+    {
+      code: 'const [color, setFlavor] = useState<string>()',
+      errors: [{
+        message: 'setState call is not destructured into value + setter pair'
+      }],
+      output: 'const [color, setColor] = useState<string>()',
+      parser: parsers.TYPESCRIPT_ESLINT
+    }
+  ].concat(
+    parsers.TS([
+      {
+        code: 'const [color, setFlavor] = useState<string>()',
+        errors: [{
+          message: 'setState call is not destructured into value + setter pair'
+        }],
+        output: 'const [color, setColor] = useState<string>()',
+        parser: parsers['@TYPESCRIPT_ESLINT']
+      }
+    ])
+  )
+};
+
+ruleTester.run('hook-set-state-names', rule, tests);