fix(eslint-plugin): [no-unnecessary-type-assertion] correct bad fix for angle bracket assertion (typescript-eslint#3244)

yeonjuan · web-flow · commit 265a039c7e72 · 2021-03-29T12:37:15.000-07:00
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts b/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts
@@ -258,15 +258,21 @@ export default util.createRule<Options, MessageIds>({
             node,
             messageId: 'unnecessaryAssertion',
             fix(fixer) {
-              return originalNode.kind === ts.SyntaxKind.TypeAssertionExpression
-                ? fixer.removeRange([
-                    node.range[0],
-                    node.expression.range[0] - 1,
-                  ])
-                : fixer.removeRange([
-                    node.expression.range[1] + 1,
-                    node.range[1],
-                  ]);
+              if (originalNode.kind === ts.SyntaxKind.TypeAssertionExpression) {
+                const closingAngleBracket = sourceCode.getTokenAfter(
+                  node.typeAnnotation,
+                );
+                return closingAngleBracket?.value === '>'
+                  ? fixer.removeRange([
+                      node.range[0],
+                      closingAngleBracket.range[1],
+                    ])
+                  : null;
+              }
+              return fixer.removeRange([
+                node.expression.range[1] + 1,
+                node.range[1],
+              ]);
             },
           });
         }
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts
@@ -358,6 +358,22 @@ function foo<T extends string>(bar: T) {
     },
     {
       code: `
+declare const foo: Foo;
+const bar = <Foo>foo;
+      `,
+      output: `
+declare const foo: Foo;
+const bar = foo;
+      `,
+      errors: [
+        {
+          messageId: 'unnecessaryAssertion',
+          line: 3,
+        },
+      ],
+    },
+    {
+      code: `
 declare function nonNull(s: string | null);
 let s: string | null = null;
 nonNull(s!);
