fix(eslint-plugin): [unbound-method] allow super expressions in this assignments (#3010)

Author: armano2

packages/eslint-plugin/src/rules/unbound-method.ts

@@ -305,7 +305,14 @@ function isSafeUse(node: TSESTree.Node): boolean {
       return ['instanceof', '==', '!=', '===', '!=='].includes(parent.operator);
 
     case AST_NODE_TYPES.AssignmentExpression:
-      return parent.operator === '=' && node === parent.left;
+      return (
+        parent.operator === '=' &&
+        (node === parent.left ||
+          (node.type === AST_NODE_TYPES.MemberExpression &&
+            node.object.type === AST_NODE_TYPES.Super &&
+            parent.left.type === AST_NODE_TYPES.MemberExpression &&
+            parent.left.object.type === AST_NODE_TYPES.ThisExpression))
+      );
 
     case AST_NODE_TYPES.ChainExpression:
     case AST_NODE_TYPES.TSNonNullExpression:

packages/eslint-plugin/tests/rules/unbound-method.test.ts

@@ -265,6 +265,22 @@ class Foo {
 }
 const { bound } = new Foo();
     `,
+    // https://github.com/typescript-eslint/typescript-eslint/issues/1866
+    `
+class BaseClass {
+  x: number = 42;
+  logThis() {}
+}
+class OtherClass extends BaseClass {
+  superLogThis: any;
+  constructor() {
+    super();
+    this.superLogThis = super.logThis;
+  }
+}
+const oc = new OtherClass();
+oc.superLogThis();
+    `,
   ],
   invalid: [
     {
@@ -529,5 +545,48 @@ const { log } = console;
         },
       ],
     },
+    // https://github.com/typescript-eslint/typescript-eslint/issues/1866
+    {
+      code: `
+class BaseClass {
+  logThis() {}
+}
+class OtherClass extends BaseClass {
+  constructor() {
+    super();
+    const x = super.logThis;
+  }
+}
+      `,
+      errors: [
+        {
+          line: 8,
+          column: 15,
+          messageId: 'unbound',
+        },
+      ],
+    },
+    // https://github.com/typescript-eslint/typescript-eslint/issues/1866
+    {
+      code: `
+class BaseClass {
+  logThis() {}
+}
+class OtherClass extends BaseClass {
+  constructor() {
+    super();
+    let x;
+    x = super.logThis;
+  }
+}
+      `,
+      errors: [
+        {
+          line: 9,
+          column: 9,
+          messageId: 'unbound',
+        },
+      ],
+    },
   ],
 });