Update: Check member expressions with this in operator-assignment (#…

…12495)
eslint · Nov 22, 2019 · 0f01f3d · 0f01f3d
1 parent 62c7038
commit 0f01f3d
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Showing 2 changed files with 55 additions and 3 deletions.
diff --git a/lib/rules/operator-assignment.js b/lib/rules/operator-assignment.js
@@ -71,6 +71,9 @@ function same(a, b) {
              */
             return same(a.object, b.object) && same(a.property, b.property);
 
+        case "ThisExpression":
+            return true;
+
         default:
             return false;
     }
@@ -83,8 +86,14 @@ function same(a, b) {
  * @returns {boolean} `true` if the node can be fixed
  */
 function canBeFixed(node) {
-    return node.type === "Identifier" ||
-        node.type === "MemberExpression" && node.object.type === "Identifier" && (!node.computed || node.property.type === "Literal");
+    return (
+        node.type === "Identifier" ||
+        (
+            node.type === "MemberExpression" &&
+            (node.object.type === "Identifier" || node.object.type === "ThisExpression") &&
+            (!node.computed || node.property.type === "Literal")
+        )
+    );
 }
 
 module.exports = {

diff --git a/tests/lib/rules/operator-assignment.js b/tests/lib/rules/operator-assignment.js
@@ -72,7 +72,19 @@ ruleTester.run("operator-assignment", rule, {
             options: ["never"]
         },
         "x = y ** x",
-        "x = x * y + z"
+        "x = x * y + z",
+        {
+            code: "this.x = this.y + z",
+            options: ["always"]
+        },
+        {
+            code: "this.x = foo.x + y",
+            options: ["always"]
+        },
+        {
+            code: "this.x = foo.this.x + y",
+            options: ["always"]
+        }
     ],
 
     invalid: [{
@@ -169,6 +181,15 @@ ruleTester.run("operator-assignment", rule, {
         output: "foo.bar = foo.bar + baz",
         options: ["never"],
         errors: UNEXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this.foo = this.foo + bar",
+        output: "this.foo += bar",
+        errors: EXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this.foo += bar",
+        output: "this.foo = this.foo + bar",
+        options: ["never"],
+        errors: UNEXPECTED_OPERATOR_ASSIGNMENT
     }, {
         code: "foo.bar.baz = foo.bar.baz + qux",
         output: null, // not fixed; fixing would cause a foo.bar getter to activate once rather than twice
@@ -178,19 +199,41 @@ ruleTester.run("operator-assignment", rule, {
         output: null, // not fixed; fixing would cause a foo.bar getter to activate twice rather than once
         options: ["never"],
         errors: UNEXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this.foo.bar = this.foo.bar + baz",
+        output: null, // not fixed; fixing would cause a this.foo getter to activate once rather than twice
+        errors: EXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this.foo.bar += baz",
+        output: null, // not fixed; fixing would cause a this.foo getter to activate twice rather than once
+        options: ["never"],
+        errors: UNEXPECTED_OPERATOR_ASSIGNMENT
     }, {
         code: "foo[bar] = foo[bar] + baz",
         output: null, // not fixed; fixing would cause bar.toString() to get called once instead of twice
         errors: EXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this[foo] = this[foo] + bar",
+        output: null, // not fixed; fixing would cause foo.toString() to get called once instead of twice
+        errors: EXPECTED_OPERATOR_ASSIGNMENT
     }, {
         code: "foo[bar] >>>= baz",
         output: null, // not fixed; fixing would cause bar.toString() to get called twice instead of once
         options: ["never"],
         errors: UNEXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this[foo] >>>= bar",
+        output: null, // not fixed; fixing would cause foo.toString() to get called twice instead of once
+        options: ["never"],
+        errors: UNEXPECTED_OPERATOR_ASSIGNMENT
     }, {
         code: "foo[5] = foo[5] / baz",
         output: "foo[5] /= baz", // this is ok because 5 is a literal, so toString won't get called
         errors: EXPECTED_OPERATOR_ASSIGNMENT
+    }, {
+        code: "this[5] = this[5] / foo",
+        output: "this[5] /= foo", // this is ok because 5 is a literal, so toString won't get called
+        errors: EXPECTED_OPERATOR_ASSIGNMENT
     }, {
         code: "/*1*/x/*2*/./*3*/y/*4*/= x.y +/*5*/z/*6*/./*7*/w/*8*/;",
         output: "/*1*/x/*2*/./*3*/y/*4*/+=/*5*/z/*6*/./*7*/w/*8*/;", // these comments are preserved