From a45eda0042b4ec8cdfa34c4909e8a4c56614f16d Mon Sep 17 00:00:00 2001
From: "claude[bot]" <41898282+claude[bot]@users.noreply.github.com>
Date: Sat, 21 Mar 2026 00:34:34 +0000
Subject: [PATCH] test(formatjs): Add regression test for issue #532 string
 concatenation in defaultMessage
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Adds an explicit regression test that reproduces the exact code from
issue #532, verifying that string concatenation like 'Hello ' + 'world'
in defaultMessage is properly evaluated rather than producing an empty array.

Co-authored-by: Donny/강동윤 <kdy1@users.noreply.github.com>
---
 packages/formatjs/__tests__/wasm.test.ts | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/packages/formatjs/__tests__/wasm.test.ts b/packages/formatjs/__tests__/wasm.test.ts
index 29780795a..93dbef47f 100644
--- a/packages/formatjs/__tests__/wasm.test.ts
+++ b/packages/formatjs/__tests__/wasm.test.ts
@@ -111,6 +111,24 @@ describe("formatjs swc plugin", () => {
     expect(output).not.toMatch(/description/);
   });
 
+  // Regression test for https://github.com/swc-project/plugins/issues/532
+  it("should handle string concatenation in defaultMessage (issue #532)", async () => {
+    const input = `
+      import { defineMessage } from 'react-intl';
+
+      const message = defineMessage({
+        defaultMessage: 'Hello ' + 'world'
+      });
+    `;
+
+    const output = await transformCode(input);
+
+    expect(output).toMatch(/id: "[^"]+"/);
+    // Should concatenate strings, not produce an empty array
+    expect(output).toMatch(/defaultMessage: "Hello world"/);
+    expect(output).not.toMatch(/defaultMessage: \[\]/);
+  });
+
   it("should handle multiple string concatenations", async () => {
     const input = `
       import { defineMessage } from 'react-intl';