Ignore negotiated group difference in real world test

rustls has X25519MLKEM768 as the default key exchange group.
OpenSSL depends on the version (3.5.0 also has X25519MLKEM768 by default)
so this test can potentially fail for different environments.

Author: ctz

tests/runner.rs

@@ -253,6 +253,11 @@ fn client_real_world() {
         .map(print_output)
         .unwrap();
 
+    let openssl_output = openssl_output
+        .replace_stdout_line("negotiated group NID: ", "negotiated group NID: <varies>");
+    let rustls_output = rustls_output
+        .replace_stdout_line("negotiated group NID: ", "negotiated group NID: <varies>");
+
     assert_eq!(openssl_output, rustls_output);
 }
 
@@ -818,6 +823,25 @@ fn print_output(out: Output) -> PrettyOutput {
 #[derive(PartialEq)]
 struct PrettyOutput(Output);
 
+impl PrettyOutput {
+    fn replace_stdout_line(mut self, prefix: &str, replace_with: &str) -> Self {
+        let mut out = String::new();
+        for line in String::from_utf8(self.0.stdout)
+            .expect("stdout should be valid utf8")
+            .lines()
+        {
+            match line.starts_with(prefix) {
+                true => out.push_str(replace_with),
+                false => out.push_str(line),
+            }
+            out.push('\n');
+        }
+
+        self.0.stdout = out.into_bytes();
+        self
+    }
+}
+
 impl fmt::Debug for PrettyOutput {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Output")