fix(eslint-plugin): [no-unnecessary-type-assertion] provide valid fix…

…es for assertions with extra tokens before `as` keyword (#8326)

* fix(eslint-plugin): [no-unnecessary-type-assertion] provide valid fixes for assertions with extra tokens before `as` keyword

* fix: provide fixes for angle bracket assertions when there're tokens inside

packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts

@@ -1,5 +1,5 @@
 import type { TSESTree } from '@typescript-eslint/utils';
-import { AST_NODE_TYPES } from '@typescript-eslint/utils';
+import { AST_NODE_TYPES, AST_TOKEN_TYPES } from '@typescript-eslint/utils';
 import { getSourceCode } from '@typescript-eslint/utils/eslint-utils';
 import * as tsutils from 'ts-api-utils';
 import * as ts from 'typescript';
@@ -263,23 +263,38 @@ export default createRule<Options, MessageIds>({
             messageId: 'unnecessaryAssertion',
             fix(fixer) {
               if (node.type === AST_NODE_TYPES.TSTypeAssertion) {
+                const openingAngleBracket = sourceCode.getTokenBefore(
+                  node.typeAnnotation,
+                  token =>
+                    token.type === AST_TOKEN_TYPES.Punctuator &&
+                    token.value === '<',
+                )!;
                 const closingAngleBracket = sourceCode.getTokenAfter(
                   node.typeAnnotation,
-                );
-                return closingAngleBracket?.value === '>'
-                  ? fixer.removeRange([
-                      node.range[0],
-                      closingAngleBracket.range[1],
-                    ])
-                  : null;
+                  token =>
+                    token.type === AST_TOKEN_TYPES.Punctuator &&
+                    token.value === '>',
+                )!;
+                // < ( number ) > ( 3 + 5 )
+                // ^---remove---^
+                return fixer.removeRange([
+                  openingAngleBracket.range[0],
+                  closingAngleBracket.range[1],
+                ]);
               }
-              return fixer.removeRange([
-                node.expression.range[1] +
-                  (node.expression.type === AST_NODE_TYPES.CallExpression
-                    ? 0
-                    : 1),
-                node.range[1],
-              ]);
+              // `as` is always present in TSAsExpression
+              const asToken = sourceCode.getTokenAfter(
+                node.expression,
+                token =>
+                  token.type === AST_TOKEN_TYPES.Identifier &&
+                  token.value === 'as',
+              )!;
+              const tokenBeforeAs = sourceCode.getTokenBefore(asToken, {
+                includeComments: true,
+              })!;
+              // ( 3 + 5 )  as  number
+              //          ^--remove--^
+              return fixer.removeRange([tokenBeforeAs.range[1], node.range[1]]);
             },
           });
         }

packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts

@@ -1,4 +1,4 @@
-import { RuleTester } from '@typescript-eslint/rule-tester';
+import { noFormat, RuleTester } from '@typescript-eslint/rule-tester';
 import path from 'path';
 
 import rule from '../../src/rules/no-unnecessary-type-assertion';
@@ -660,5 +660,160 @@ const item = arr[0];
         },
       ],
     },
+    {
+      code: noFormat`
+const foo = (  3 + 5  ) as number;
+      `,
+      output: `
+const foo = (  3 + 5  );
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = (  3 + 5  ) /*as*/ as number;
+      `,
+      output: `
+const foo = (  3 + 5  ) /*as*/;
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = (  3 + 5
+  ) /*as*/ as //as
+  (
+    number
+  );
+      `,
+      output: `
+const foo = (  3 + 5
+  ) /*as*/;
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = (3 + (5 as number) ) as number;
+      `,
+      output: `
+const foo = (3 + (5 as number) );
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = 3 + 5/*as*/ as number;
+      `,
+      output: `
+const foo = 3 + 5/*as*/;
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = 3 + 5/*a*/ /*b*/ as number;
+      `,
+      output: `
+const foo = 3 + 5/*a*/ /*b*/;
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = <(number)>(3 + 5);
+      `,
+      output: `
+const foo = (3 + 5);
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = < ( number ) >( 3 + 5 );
+      `,
+      output: `
+const foo = ( 3 + 5 );
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = <number> /* a */ (3 + 5);
+      `,
+      output: `
+const foo =  /* a */ (3 + 5);
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+const foo = <number /* a */>(3 + 5);
+      `,
+      output: `
+const foo = (3 + 5);
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 2,
+          column: 13,
+        },
+      ],
+    },
   ],
 });