From 66e9c6e29f9f56bbd178ba6405f47053be591258 Mon Sep 17 00:00:00 2001
From: kangdaehoon <kdhoon07@gmail.com>
Date: Mon, 26 Oct 2020 06:57:35 +0900
Subject: [PATCH] fix(eslint-plugin): [prefer-string-starts-ends-with] Check
 negative indices in the second position for slice (#2696)

---
 .../src/rules/prefer-string-starts-ends-with.ts        |  3 ++-
 .../tests/rules/prefer-string-starts-ends-with.test.ts | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/packages/eslint-plugin/src/rules/prefer-string-starts-ends-with.ts b/packages/eslint-plugin/src/rules/prefer-string-starts-ends-with.ts
index 3126f616038..f4697b7c01d 100644
--- a/packages/eslint-plugin/src/rules/prefer-string-starts-ends-with.ts
+++ b/packages/eslint-plugin/src/rules/prefer-string-starts-ends-with.ts
@@ -575,7 +575,8 @@ export default createRule({
         const isStartsWith =
           !isEndsWith &&
           callNode.arguments.length === 2 &&
-          isNumber(callNode.arguments[0], 0);
+          isNumber(callNode.arguments[0], 0) &&
+          !isNegativeIndexExpression(callNode.arguments[1], node.object);
         if (!isStartsWith && !isEndsWith) {
           return;
         }
diff --git a/packages/eslint-plugin/tests/rules/prefer-string-starts-ends-with.test.ts b/packages/eslint-plugin/tests/rules/prefer-string-starts-ends-with.test.ts
index e97fa912df5..0cef89740d5 100644
--- a/packages/eslint-plugin/tests/rules/prefer-string-starts-ends-with.test.ts
+++ b/packages/eslint-plugin/tests/rules/prefer-string-starts-ends-with.test.ts
@@ -230,6 +230,16 @@ ruleTester.run('prefer-string-starts-ends-with', rule, {
         x.test(s)
       }
     `,
+    `
+      function f(s: string) {
+        s.slice(0, -4) === "car"
+      }
+    `,
+    `
+      function f(x: string, s: string) {
+        x.endsWith('foo') && x.slice(0, -4) === 'bar'
+      }
+    `,
   ]),
   invalid: addOptional([
     // String indexing.