From ba80a4c01b1086f6fd1202ebc9c262fc5f05b65b Mon Sep 17 00:00:00 2001
From: Yannick Croissant <yannick.croissant@gmail.com>
Date: Sun, 6 Jan 2019 21:21:25 +0100
Subject: [PATCH] [Fix] Detect components with return statement in switch/case

Fixes #2118
---
 lib/util/ast.js                          | 20 ++++++++++++++------
 tests/lib/rules/no-unused-prop-types.js  | 24 ++++++++++++++++++++++++
 tests/lib/rules/prop-types.js            | 19 +++++++++++++++++++
 tests/lib/rules/require-default-props.js | 23 +++++++++++++++++++++++
 4 files changed, 80 insertions(+), 6 deletions(-)

diff --git a/lib/util/ast.js b/lib/util/ast.js
index 90d41a2d5b..530c889e7f 100644
--- a/lib/util/ast.js
+++ b/lib/util/ast.js
@@ -18,13 +18,21 @@ function findReturnStatement(node) {
 
   const bodyNodes = (node.value ? node.value.body.body : node.body.body);
 
-  let i = bodyNodes.length - 1;
-  for (; i >= 0; i--) {
-    if (bodyNodes[i].type === 'ReturnStatement') {
-      return bodyNodes[i];
+  return (function loopNodes(nodes) {
+    let i = nodes.length - 1;
+    for (; i >= 0; i--) {
+      if (nodes[i].type === 'ReturnStatement') {
+        return nodes[i];
+      }
+      if (nodes[i].type === 'SwitchStatement') {
+        let j = nodes[i].cases.length - 1;
+        for (; j >= 0; j--) {
+          return loopNodes(nodes[i].cases[j].consequent);
+        }
+      }
     }
-  }
-  return false;
+    return false;
+  }(bodyNodes));
 }
 
 /**
diff --git a/tests/lib/rules/no-unused-prop-types.js b/tests/lib/rules/no-unused-prop-types.js
index 1483370ff0..17f95dc112 100644
--- a/tests/lib/rules/no-unused-prop-types.js
+++ b/tests/lib/rules/no-unused-prop-types.js
@@ -4961,6 +4961,30 @@ ruleTester.run('no-unused-prop-types', rule, {
       errors: [{
         message: '\'person.lastname\' PropType is defined but prop is never used'
       }]
+    }, {
+      code: `
+        import PropTypes from 'prop-types';
+        import React from 'react';
+
+        const MyComponent= (props) => {
+          switch (props.usedProp) {
+            case 1:
+              return (<div />);
+            default:
+              return <div />;
+          }
+        };
+
+        MyComponent.propTypes = {
+          usedProp: PropTypes.string,
+          unUsedProp: PropTypes.string,
+        };
+
+        export default MyComponent;
+      `,
+      errors: [{
+        message: '\'unUsedProp\' PropType is defined but prop is never used'
+      }]
     }
 
     /* , {
diff --git a/tests/lib/rules/prop-types.js b/tests/lib/rules/prop-types.js
index 70f1ac0807..b72f043abc 100644
--- a/tests/lib/rules/prop-types.js
+++ b/tests/lib/rules/prop-types.js
@@ -4334,6 +4334,25 @@ ruleTester.run('prop-types', rule, {
       errors: [{
         message: '\'text\' is missing in props validation'
       }]
+    }, {
+      code: `
+        import PropTypes from 'prop-types';
+        import React from 'react';
+
+        const MyComponent = (props) => {
+          switch (props.usedProp) {
+            case 1:
+              return (<div />);
+            default:
+              return <div />;
+          }
+        };
+
+        export default MyComponent;
+      `,
+      errors: [{
+        message: '\'usedProp\' is missing in props validation'
+      }]
     }
   ]
 });
diff --git a/tests/lib/rules/require-default-props.js b/tests/lib/rules/require-default-props.js
index a7a40d6207..200986b81b 100644
--- a/tests/lib/rules/require-default-props.js
+++ b/tests/lib/rules/require-default-props.js
@@ -2199,6 +2199,29 @@ ruleTester.run('require-default-props', rule, {
       errors: [{
         message: 'propType "name" is not required, but has no corresponding defaultProps declaration.'
       }]
+    }, {
+      code: `
+        import PropTypes from 'prop-types';
+        import React from 'react';
+
+        const MyComponent= (props) => {
+          switch (props.usedProp) {
+            case 1:
+              return (<div />);
+            default:
+              return <div />;
+          }
+        };
+
+        MyComponent.propTypes = {
+          usedProp: PropTypes.string,
+        };
+
+        export default MyComponent;
+      `,
+      errors: [{
+        message: 'propType "usedProp" is not required, but has no corresponding defaultProps declaration.'
+      }]
     }
   ]
 });