From f79c63e6da2f7326c7a3d02bda1c501749f7f16d Mon Sep 17 00:00:00 2001
From: Evgueni Naverniouk <evgueni.naverniouk@cumul8.com>
Date: Tue, 13 Sep 2016 12:06:13 -0700
Subject: [PATCH] Fixes Issue #825

---
 lib/rules/no-unused-prop-types.js       |  2 +-
 tests/lib/rules/no-unused-prop-types.js | 32 +++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/lib/rules/no-unused-prop-types.js b/lib/rules/no-unused-prop-types.js
index 1d0bb94dd9..4c2c146c95 100644
--- a/lib/rules/no-unused-prop-types.js
+++ b/lib/rules/no-unused-prop-types.js
@@ -619,7 +619,7 @@ module.exports = {
           });
           break;
         case 'destructuring':
-          for (var k = 0, l = properties.length; k < l; k++) {
+          for (var k = 0, l = (properties || []).length; k < l; k++) {
             if (hasSpreadOperator(properties[k]) || properties[k].computed) {
               continue;
             }
diff --git a/tests/lib/rules/no-unused-prop-types.js b/tests/lib/rules/no-unused-prop-types.js
index 986a42dd84..291323c141 100644
--- a/tests/lib/rules/no-unused-prop-types.js
+++ b/tests/lib/rules/no-unused-prop-types.js
@@ -1382,6 +1382,20 @@ ruleTester.run('no-unused-prop-types', rule, {
       ].join('\n'),
       parser: 'babel-eslint',
       parserOptions: parserOptions
+    }, {
+      // Destructured state props in `componentDidUpdate` [Issue #825]
+      code: [
+        'class Hello extends Component {',
+        '  static propTypes = {',
+        '    something: PropTypes.bool',
+        '  }',
+        '  componentDidUpdate ({something}, {state1, state2}) {',
+        '    return something;',
+        '  }',
+        '}'
+      ].join('\n'),
+      parser: 'babel-eslint',
+      parserOptions: parserOptions
     }
   ],
 
@@ -2337,6 +2351,24 @@ ruleTester.run('no-unused-prop-types', rule, {
         line: 3,
         column: 13
       }]
+    }, {
+      code: [
+        'class Hello extends Component {',
+        '  static propTypes = {',
+        '    something: PropTypes.bool',
+        '  }',
+        '  componentDidUpdate (prevProps, {state1, state2}) {',
+        '    return something;',
+        '  }',
+        '}'
+      ].join('\n'),
+      parser: 'babel-eslint',
+      parserOptions: parserOptions,
+      errors: [{
+        message: '\'something\' PropType is defined but prop is never used',
+        line: 3,
+        column: 16
+      }]
     }/* , {
       // Enable this when the following issue is fixed
       // https://github.com/yannickcr/eslint-plugin-react/issues/296