test: Don't fail on Windows without echo and GNU ls

`test_exec_with_separator` runs `echo`, which is only a shell builtin on
Windows. Skip it there, like the other `echo` tests.

`test_list_details` requires GNU `ls` on Windows. Without it, check that
`--list-details` reports that it is not supported.

Fixes #1332

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/tests.rs

@@ -2110,6 +2110,7 @@ fn test_exec_batch_with_limit() {
 }
 
 /// Shell script execution (--exec) with a custom --path-separator
+#[cfg(not(windows))] // Windows has no `echo` executable, only the shell builtin
 #[test]
 fn test_exec_with_separator() {
     let (te, abs_path) = get_test_env_with_abs_path(DEFAULT_DIRS, DEFAULT_FILES);
@@ -2650,6 +2651,20 @@ fn test_exec_invalid_utf8() {
 fn test_list_details() {
     let te = TestEnv::new(DEFAULT_DIRS, DEFAULT_FILES);
 
+    // On Windows, 'fd --list-details' needs GNU 'ls'.
+    if cfg!(windows)
+        && std::process::Command::new("ls")
+            .arg("--version")
+            .output()
+            .is_err()
+    {
+        te.assert_failure_with_error(
+            &["--list-details"],
+            "[fd error]: 'fd --list-details' is not supported on Windows unless GNU 'ls' is installed.",
+        );
+        return;
+    }
+
     // Make sure we can execute 'fd --list-details' without any errors.
     te.assert_success_and_get_output(".", &["--list-details"]);
 }