From 9c8203f15854293f67dac7ea201c6a2ee527edc1 Mon Sep 17 00:00:00 2001
From: Alexander T <alexander.tarasyuk@outlook.com>
Date: Thu, 14 Nov 2019 19:15:39 +0200
Subject: [PATCH] fix(eslint-plugin): [camelcase] handle optional member expr
 (#1204)

---
 packages/eslint-plugin/src/rules/camelcase.ts | 42 ++++++++++++------
 .../tests/rules/camelcase.test.ts             | 44 +++++++++++++++++++
 2 files changed, 73 insertions(+), 13 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/camelcase.ts b/packages/eslint-plugin/src/rules/camelcase.ts
index 4bb614cba9d..0928484b629 100644
--- a/packages/eslint-plugin/src/rules/camelcase.ts
+++ b/packages/eslint-plugin/src/rules/camelcase.ts
@@ -72,23 +72,28 @@ export default util.createRule<Options, MessageIds>({
      * @private
      */
     function isTSPropertyType(node: TSESTree.Node): boolean {
-      if (!node.parent) {
-        return false;
-      }
-      if (TS_PROPERTY_TYPES.includes(node.parent.type)) {
+      if (TS_PROPERTY_TYPES.includes(node.type)) {
         return true;
       }
 
-      if (node.parent.type === AST_NODE_TYPES.AssignmentPattern) {
+      if (node.type === AST_NODE_TYPES.AssignmentPattern) {
         return (
-          node.parent.parent !== undefined &&
-          TS_PROPERTY_TYPES.includes(node.parent.parent.type)
+          node.parent !== undefined &&
+          TS_PROPERTY_TYPES.includes(node.parent.type)
         );
       }
 
       return false;
     }
 
+    function report(node: TSESTree.Identifier): void {
+      context.report({
+        node,
+        messageId: 'notCamelCase',
+        data: { name: node.name },
+      });
+    }
+
     return {
       Identifier(node): void {
         /*
@@ -103,13 +108,24 @@ export default util.createRule<Options, MessageIds>({
         }
 
         // Check TypeScript specific nodes
-        if (isTSPropertyType(node)) {
+        const parent = node.parent;
+        if (parent && isTSPropertyType(parent)) {
           if (properties === 'always' && isUnderscored(name)) {
-            context.report({
-              node,
-              messageId: 'notCamelCase',
-              data: { name: node.name },
-            });
+            report(node);
+          }
+
+          return;
+        }
+
+        if (parent && parent.type === AST_NODE_TYPES.OptionalMemberExpression) {
+          // Report underscored object names
+          if (
+            properties === 'always' &&
+            parent.object.type === AST_NODE_TYPES.Identifier &&
+            parent.object.name === node.name &&
+            isUnderscored(name)
+          ) {
+            report(node);
           }
 
           return;
diff --git a/packages/eslint-plugin/tests/rules/camelcase.test.ts b/packages/eslint-plugin/tests/rules/camelcase.test.ts
index e0e142c70a4..d2d3287ce66 100644
--- a/packages/eslint-plugin/tests/rules/camelcase.test.ts
+++ b/packages/eslint-plugin/tests/rules/camelcase.test.ts
@@ -79,6 +79,22 @@ ruleTester.run('camelcase', rule, {
       code: 'abstract class Foo { abstract bar: number = 0; }',
       options: [{ properties: 'always' }],
     },
+    {
+      code: 'const foo = foo?.baz;',
+    },
+    {
+      code: 'const foo = foo?.foo_bar?.foo_bar_baz;',
+    },
+    {
+      code: 'const foo = foo.bar?.foo_bar_baz;',
+    },
+    {
+      code: 'const foo = (foo?.bar?.baz)?.foo_bar_baz;',
+    },
+    {
+      code: 'const foo = foo_bar?.foo;',
+      options: [{ properties: 'never' }],
+    },
   ],
 
   invalid: [
@@ -194,5 +210,33 @@ ruleTester.run('camelcase', rule, {
         },
       ],
     },
+    {
+      code: 'const foo = foo_bar?.foo;',
+      options: [{ properties: 'always' }],
+      errors: [
+        {
+          messageId: 'notCamelCase',
+          data: {
+            name: 'foo_bar',
+          },
+          line: 1,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: 'const foo = (foo_test?.bar)?.baz;',
+      options: [{ properties: 'always' }],
+      errors: [
+        {
+          messageId: 'notCamelCase',
+          data: {
+            name: 'foo_test',
+          },
+          line: 1,
+          column: 14,
+        },
+      ],
+    },
   ],
 });