fix(eslint-plugin): [no-unnecessary-condition] improve optional chain handling (typescript-eslint#2111)

yeonjuan · web-flow · commit 9ee399b5906e · 2020-05-30T14:48:14.000-07:00
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts b/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
@@ -20,6 +20,7 @@ import {
   isNullableType,
   nullThrows,
   NullThrowsReasons,
+  isMemberOrOptionalMemberExpression,
 } from '../util';
 
 const typeContainsFlag = (type: ts.Type, flag: ts.TypeFlags): boolean => {
@@ -439,7 +440,11 @@ export default createRule<Options, MessageId>({
         return;
       }
 
-      const type = getNodeType(node);
+      const nodeToCheck = isMemberOrOptionalMemberExpression(node)
+        ? node.object
+        : node;
+      const type = getNodeType(nodeToCheck);
+
       if (
         isTypeFlagSet(type, ts.TypeFlags.Any) ||
         isTypeFlagSet(type, ts.TypeFlags.Unknown) ||
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
@@ -724,5 +724,62 @@ foo
         },
       ],
     },
+    {
+      code: `
+declare const x: { a?: { b: string } };
+x?.a?.b;
+      `,
+      output: `
+declare const x: { a?: { b: string } };
+x.a?.b;
+      `,
+      errors: [
+        {
+          messageId: 'neverOptionalChain',
+          line: 3,
+          endLine: 3,
+          column: 2,
+          endColumn: 4,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: { a: { b?: { c: string } } };
+x.a?.b?.c;
+      `,
+      output: `
+declare const x: { a: { b?: { c: string } } };
+x.a.b?.c;
+      `,
+      errors: [
+        {
+          messageId: 'neverOptionalChain',
+          line: 3,
+          endLine: 3,
+          column: 4,
+          endColumn: 6,
+        },
+      ],
+    },
+    {
+      code: `
+let x: { a?: string };
+x?.a;
+      `,
+      output: `
+let x: { a?: string };
+x.a;
+      `,
+      errors: [
+        {
+          messageId: 'neverOptionalChain',
+          line: 3,
+          endLine: 3,
+          column: 2,
+          endColumn: 4,
+        },
+      ],
+    },
   ],
 });
