From 4a4b6995350eaef920d85924ffbf99a030c231e9 Mon Sep 17 00:00:00 2001
From: Luca Haneklau <git@luca.lsys.ac>
Date: Sun, 12 May 2024 21:36:51 +0200
Subject: [PATCH] fix(dev-server-core): fix readonly error serialization

---
 .changeset/cool-terms-exercise.md                    |  5 +++++
 .../browser-tests/fail-readonly-actual.test.js       |  6 ++++++
 .../tests/test-failure/runTestFailureTest.ts         | 12 ++++++++++++
 .../src/web-sockets/webSocketsPlugin.ts              |  3 ++-
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/cool-terms-exercise.md
 create mode 100644 integration/test-runner/tests/test-failure/browser-tests/fail-readonly-actual.test.js

diff --git a/.changeset/cool-terms-exercise.md b/.changeset/cool-terms-exercise.md
new file mode 100644
index 000000000..7af291bbb
--- /dev/null
+++ b/.changeset/cool-terms-exercise.md
@@ -0,0 +1,5 @@
+---
+'@web/dev-server-core': patch
+---
+
+Fix readonly object serialization
diff --git a/integration/test-runner/tests/test-failure/browser-tests/fail-readonly-actual.test.js b/integration/test-runner/tests/test-failure/browser-tests/fail-readonly-actual.test.js
new file mode 100644
index 000000000..70fa5e72b
--- /dev/null
+++ b/integration/test-runner/tests/test-failure/browser-tests/fail-readonly-actual.test.js
@@ -0,0 +1,6 @@
+import { expect } from '../../../../../node_modules/@esm-bundle/chai/esm/chai.js';
+
+it('readonly actual', function() {
+  const fixture = Object.freeze({x: {}});
+  expect(fixture).to.equal(null);
+})
diff --git a/integration/test-runner/tests/test-failure/runTestFailureTest.ts b/integration/test-runner/tests/test-failure/runTestFailureTest.ts
index 50aad98ca..85be1a0c2 100644
--- a/integration/test-runner/tests/test-failure/runTestFailureTest.ts
+++ b/integration/test-runner/tests/test-failure/runTestFailureTest.ts
@@ -208,5 +208,17 @@ export function runTestFailureTest(
         expect(session.errors).to.eql([ERROR_NOT_IMPORTABLE]);
       }
     });
+
+    it('handles tests that error with a readonly actual', () => {
+      const sessions = allSessions.filter(s => s.testFile.endsWith('fail-readonly-actual.test.js'));
+      expect(sessions.length === browserCount).to.equal(true);
+      for (const session of sessions) {
+        expect(session.testResults!.tests.map(t => t.name)).to.eql(['readonly actual']);
+        expect(session.passed).to.be.false;
+        expect(session.testResults!.tests![0].error!.message).to.equal(
+          'expected { x: {} } to equal null',
+        );
+      }
+    });
   });
 }
diff --git a/packages/dev-server-core/src/web-sockets/webSocketsPlugin.ts b/packages/dev-server-core/src/web-sockets/webSocketsPlugin.ts
index d2ca58aa3..ce760d4db 100644
--- a/packages/dev-server-core/src/web-sockets/webSocketsPlugin.ts
+++ b/packages/dev-server-core/src/web-sockets/webSocketsPlugin.ts
@@ -40,7 +40,8 @@ export function webSocketsPlugin(): Plugin {
         }
 
         export function stable (obj, replacer, spacer) {
-          var tmp = deterministicDecirc(obj, '', [], undefined) || obj
+          var target = structuredClone(obj)
+          var tmp = deterministicDecirc(target, '', [], undefined) || target
           var res
           if (replacerStack.length === 0) {
             res = JSON.stringify(tmp, replacer, spacer)