Make no-unused-collection not trigger if writing to elements of said collection (#452)

Author: zglicz

src/rules/no-unused-collection.ts

@@ -184,10 +184,7 @@ function isElementWrite(statement: TSESTree.ExpressionStatement, ref: TSESLint.S
 }
 
 function isMemberExpressionReference(lhs: TSESTree.Node, ref: TSESLint.Scope.Reference): boolean {
-  return (
-    lhs.type === 'MemberExpression' &&
-    (isReferenceTo(ref, lhs.object) || isMemberExpressionReference(lhs.object, ref))
-  );
+  return lhs.type === 'MemberExpression' && isReferenceTo(ref, lhs.object);
 }
 
 function isIdentifier(node: TSESTree.Node, ...values: string[]): node is TSESTree.Identifier {

tests/rules/no-unused-collection.test.ts

@@ -34,7 +34,7 @@ function invalidTest(code: string) {
   };
 }
 
-ruleTester.run('Primitive return types should be used.', rule, {
+ruleTester.run('Collection contents should be used', rule, {
   valid: [
     {
       code: `
@@ -169,6 +169,13 @@ ruleTester.run('Primitive return types should be used.', rule, {
     {
       code: `export const collection = new Map()`,
     },
+    {
+      code: `
+        const a = {foo: false};
+        const xs = [a];
+        xs[0].foo = true;
+      `,
+    },
   ],
   invalid: [
     {
@@ -197,11 +204,6 @@ ruleTester.run('Primitive return types should be used.', rule, {
           arrayConstructor[1] = 42;
       }
       `),
-    invalidTest(`function nok2_1() {
-          let arrayConstructor = new Array(); // Noncompliant
-          arrayConstructor[1][2] = 42;
-      }
-      `),
     invalidTest(`function nok3() {
           let arrayWithoutNew = Array(); // Noncompliant
           arrayWithoutNew[1] = 42;