From 5ac329e16b54256d4d817d1cdbf29e77e0a837f0 Mon Sep 17 00:00:00 2001
From: mdm317 <dbswh1008@gmail.com>
Date: Thu, 18 Sep 2025 13:43:12 +0900
Subject: [PATCH] report only when ternary is top-level inside Boolean

---
 .../src/rules/prefer-nullish-coalescing.ts    |  6 +-
 .../rules/prefer-nullish-coalescing.test.ts   | 84 +++++++++++++------
 2 files changed, 63 insertions(+), 27 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
index d611e7b079a9..0956b558b10a 100644
--- a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
+++ b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
@@ -301,7 +301,11 @@ export default createRule<Options, MessageIds>({
 
       if (
         ignoreBooleanCoercion === true &&
-        isBooleanConstructorContext(node, context)
+        isBooleanConstructorContext(node, context) &&
+        !(
+          node.type === AST_NODE_TYPES.ConditionalExpression &&
+          node.parent.type === AST_NODE_TYPES.CallExpression
+        )
       ) {
         return false;
       }
diff --git a/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts b/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts
index 618d1c244414..e2c5f17c8e5d 100644
--- a/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts
+++ b/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts
@@ -1253,32 +1253,6 @@ const test = Boolean(((a = b), b || c));
     },
     {
       code: `
-let a: string | true | undefined;
-let b: string | boolean | undefined;
-
-const x = Boolean(a ? a : b);
-      `,
-      options: [
-        {
-          ignoreBooleanCoercion: true,
-        },
-      ],
-    },
-    {
-      code: `
-let a: string | boolean | undefined;
-let b: string | boolean | undefined;
-
-const test = Boolean(!a ? b : a);
-      `,
-      options: [
-        {
-          ignoreBooleanCoercion: true,
-        },
-      ],
-    },
-    {
-      code: `
 let a: string | boolean | undefined;
 let b: string | boolean | undefined;
 let c: string | boolean | undefined;
@@ -5089,6 +5063,64 @@ const x = Boolean(1 + (a ?? b));
 let a: string | true | undefined;
 let b: string | boolean | undefined;
 
+const x = Boolean(a ? a : b);
+      `,
+      errors: [
+        {
+          messageId: 'preferNullishOverTernary',
+          suggestions: [
+            {
+              messageId: 'suggestNullish',
+              output: `
+let a: string | true | undefined;
+let b: string | boolean | undefined;
+
+const x = Boolean(a ?? b);
+      `,
+            },
+          ],
+        },
+      ],
+      options: [
+        {
+          ignoreBooleanCoercion: true,
+        },
+      ],
+    },
+    {
+      code: `
+let a: string | boolean | undefined;
+let b: string | boolean | undefined;
+
+const test = Boolean(!a ? b : a);
+      `,
+      errors: [
+        {
+          messageId: 'preferNullishOverTernary',
+          suggestions: [
+            {
+              messageId: 'suggestNullish',
+              output: `
+let a: string | boolean | undefined;
+let b: string | boolean | undefined;
+
+const test = Boolean(a ?? b);
+      `,
+            },
+          ],
+        },
+      ],
+      options: [
+        {
+          ignoreBooleanCoercion: true,
+        },
+      ],
+    },
+    {
+      code: `
+let a: string | true | undefined;
+let b: string | boolean | undefined;
+
 declare function f(x: unknown): unknown;
 
 if (f(a || b)) {