typescript-eslint · bradzacher · Nov 16, 2024 · Nov 7, 2024 · Nov 7, 2024 · Nov 8, 2024
diff --git a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
@@ -476,6 +476,13 @@ function isConditionalTest(node: TSESTree.Node): boolean {
     return isConditionalTest(parent);
   }
 
+  if (
+    parent.type === AST_NODE_TYPES.UnaryExpression &&
+    parent.operator === '!'
+  ) {
+    return isConditionalTest(parent);
+  }
+
   if (
     (parent.type === AST_NODE_TYPES.ConditionalExpression ||
       parent.type === AST_NODE_TYPES.DoWhileStatement ||

diff --git a/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts b/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts
@@ -575,6 +575,34 @@ let b: string | boolean | undefined;
 let c: string | boolean | undefined;
 
 if (((a = b), b || c)) {
+}
+      `,
+      options: [
+        {
+          ignoreConditionalTests: true,
+        },
+      ],
+    },
+    {
+      code: `
+let a: string | undefined;
+let b: string | undefined;
+
+if (!(a || b)) {
+}
+      `,
+      options: [
+        {
+          ignoreConditionalTests: true,
+        },
+      ],
+    },
+    {
+      code: `
+let a: string | undefined;
+let b: string | undefined;
+
+if (!!(a || b)) {
 }
       `,
       options: [
@@ -2266,7 +2294,38 @@ if (f(a ?? b)) {
       ],
       options: [
         {
-          ignoreBooleanCoercion: true,
+          ignoreConditionalTests: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const a: string | undefined;
+declare const b: string;
+
+if (+(a || b)) {
+}
+      `,
+      errors: [
+        {
+          messageId: 'preferNullishOverOr',
+          suggestions: [
+            {
+              messageId: 'suggestNullish',
+              output: `
+declare const a: string | undefined;
+declare const b: string;
+
+if (+(a ?? b)) {
+}
+      `,
+            },
+          ],
+        },
+      ],
+      options: [
+        {
+          ignoreConditionalTests: true,
         },
       ],
     },