fix: apply_patch shell_serialization tests (#4786)

## Summary
Adds additional shell_serialization tests specifically for apply_patch
and other cases.

## Test Plan
- [x] These are all tests

codex-rs/core/tests/suite/tool_harness.rs

@@ -1,5 +1,7 @@
 #![cfg(not(target_os = "windows"))]
 
+use std::fs;
+
 use assert_matches::assert_matches;
 use codex_core::features::Feature;
 use codex_core::model_family::find_family_for_model;
@@ -295,15 +297,19 @@ async fn apply_patch_tool_executes_and_emits_patch_events() -> anyhow::Result<()
         ..
     } = builder.build(&server).await?;
 
+    let file_name = "notes.txt";
+    let file_path = cwd.path().join(file_name);
     let call_id = "apply-patch-call";
-    let patch_content = r#"*** Begin Patch
-*** Add File: notes.txt
+    let patch_content = format!(
+        r#"*** Begin Patch
+*** Add File: {file_name}
 +Tool harness apply patch
-*** End Patch"#;
+*** End Patch"#
+    );
 
     let first_response = sse(vec![
         ev_response_created("resp-1"),
-        ev_apply_patch_function_call(call_id, patch_content),
+        ev_apply_patch_function_call(call_id, &patch_content),
         ev_completed("resp-1"),
     ]);
     responses::mount_sse_once_match(&server, any(), first_response).await;
@@ -352,6 +358,7 @@ async fn apply_patch_tool_executes_and_emits_patch_events() -> anyhow::Result<()
     assert!(saw_patch_begin, "expected PatchApplyBegin event");
     let patch_end_success =
         patch_end_success.expect("expected PatchApplyEnd event to capture success flag");
+    assert!(patch_end_success);
 
     let req = second_mock.single_request();
     let output_item = req.function_call_output(call_id);
@@ -361,38 +368,21 @@ async fn apply_patch_tool_executes_and_emits_patch_events() -> anyhow::Result<()
     );
     let output_text = extract_output_text(&output_item).expect("output text present");
 
-    if let Ok(exec_output) = serde_json::from_str::<Value>(output_text) {
-        let exit_code = exec_output["metadata"]["exit_code"]
-            .as_i64()
-            .expect("exit_code present");
-        let summary = exec_output["output"].as_str().expect("output field");
-        assert_eq!(
-            exit_code, 0,
-            "expected apply_patch exit_code=0, got {exit_code}, summary: {summary:?}"
-        );
-        assert!(
-            patch_end_success,
-            "expected PatchApplyEnd success flag, summary: {summary:?}"
-        );
-        assert!(
-            summary.contains("Success."),
-            "expected apply_patch summary to note success, got {summary:?}"
-        );
+    let expected_pattern = format!(
+        r"(?s)^Exit code: 0
+Wall time: [0-9]+(?:\.[0-9]+)? seconds
+Output:
+Success. Updated the following files:
+A {file_name}
+?$"
+    );
+    assert_regex_match(&expected_pattern, output_text);
 
-        let patched_path = cwd.path().join("notes.txt");
-        let contents = std::fs::read_to_string(&patched_path)
-            .unwrap_or_else(|e| panic!("failed reading {}: {e}", patched_path.display()));
-        assert_eq!(contents, "Tool harness apply patch\n");
-    } else {
-        assert!(
-            output_text.contains("codex-run-as-apply-patch"),
-            "expected apply_patch failure message to mention codex-run-as-apply-patch, got {output_text:?}"
-        );
-        assert!(
-            !patch_end_success,
-            "expected PatchApplyEnd to report success=false when apply_patch invocation fails"
-        );
-    }
+    let updated_contents = fs::read_to_string(file_path)?;
+    assert_eq!(
+        updated_contents, "Tool harness apply patch\n",
+        "expected updated file content"
+    );
 
     Ok(())
 }