test(tail): fix flaky test_follow_name_multiple on macOS

Increase timeout from 500ms to 3000ms on macOS to account for file system
caching delays when reading redirected output from temp files.

Author: naoNao89

tests/by-util/test_tail.rs

@@ -597,10 +597,18 @@ fn test_follow_name_multiple() {
             .arg(FOOBAR_2_TXT)
             .run_no_wait();
 
+        // On macOS, file system caching can cause a delay of 2-3 seconds before
+        // output written to a redirected stdout temp file becomes visible to other
+        // file handles reading that same file. Increase timeout to 3000ms on macOS.
+        #[cfg(target_os = "macos")]
+        let initial_delay = 3000;
+        #[cfg(not(target_os = "macos"))]
+        let initial_delay = 500;
+
         child
-            .make_assertion_with_delay(500)
+            .make_assertion_with_delay(initial_delay)
             .is_alive()
-            .with_current_output()
+            .with_all_output()
             .stdout_only_fixture("foobar_follow_multiple.expected");
 
         let first_append = "trois\n";