prefer-object-spread: ignore Object.assign({}, this)

src/rules/preferObjectSpreadRule.ts

@@ -16,8 +16,14 @@
  */
 
 import {
-    hasSideEffects, isCallExpression, isExpressionValueUsed, isIdentifier, isObjectLiteralExpression,
-    isPropertyAccessExpression, isSpreadElement, SideEffectOptions,
+    hasSideEffects,
+    isCallExpression,
+    isExpressionValueUsed,
+    isIdentifier,
+    isObjectLiteralExpression,
+    isPropertyAccessExpression,
+    isSpreadElement,
+    SideEffectOptions,
 } from "tsutils";
 import * as ts from "typescript";
 
@@ -52,12 +58,20 @@ function walk(ctx: Lint.WalkContext<void>) {
             isIdentifier(node.expression.expression) && node.expression.expression.text === "Object" &&
             !ts.isFunctionLike(node.arguments[0]) &&
             // Object.assign(...someArray) cannot be written as object spread
-            !node.arguments.some(isSpreadElement)) {
+            !node.arguments.some(isSpreadElement) &&
+            /**
+             * @TODO
+             * Remove !node.arguments.some(isThisKeyword) when typescript get's
+             * support for spread types.
+             * PR: https://github.com/Microsoft/TypeScript/issues/10727
+             */
+            !node.arguments.some(isThisKeyword)) {
             if (node.arguments[0].kind === ts.SyntaxKind.ObjectLiteralExpression) {
                 ctx.addFailureAtNode(node, Rule.FAILURE_STRING, createFix(node, ctx.sourceFile));
             } else if (isExpressionValueUsed(node) && !hasSideEffects(node.arguments[0], SideEffectOptions.Constructor)) {
                 ctx.addFailureAtNode(node, Rule.ASSIGNMENT_FAILURE_STRING, createFix(node, ctx.sourceFile));
             }
+
         }
         return ts.forEachChild(node, cb);
     });
@@ -102,6 +116,10 @@ function createFix(node: ts.CallExpression, sourceFile: ts.SourceFile): Lint.Fix
     return fix;
 }
 
+function isThisKeyword(node: ts.Expression): boolean {
+    return node.kind === ts.SyntaxKind.ThisKeyword;
+}
+
 function needsParens(node: ts.Node): boolean {
     switch (node.kind) {
         case ts.SyntaxKind.ConditionalExpression:

test/rules/prefer-object-spread/test.ts.fix

@@ -1,3 +1,6 @@
+const form = Object.assign({}, this);
+const foo = Object.assign(bar, this);
+const foo = Object.assign({}, bar, baz, this);
 const original = {a: 1, b:2};
 {...original, c: 3};
 {a: 1, b: 2, c: 3};

test/rules/prefer-object-spread/test.ts.lint

@@ -1,3 +1,6 @@
+const form = Object.assign({}, this);
+const foo = Object.assign(bar, this);
+const foo = Object.assign({}, bar, baz, this);
 const original = {a: 1, b:2};
 Object.assign({}, original, {c: 3});
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [0]