Update tests8.rs

Author: 13001288072

exercises/tests/tests8.rs

@@ -1,25 +1,12 @@
-// tests8.rs
-//
-// This execrise shares `build.rs` with the previous exercise.
-// You need to add some code to `build.rs` to make both this exercise and
-// the previous one work.
-//
-// Execute `rustlings hint tests8` or use the `hint` watch subcommand for a
-// hint.
-
-// I AM NOT DONE
-
-fn main() {}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_success() {
-        #[cfg(feature = "pass")]
-        return;
-
-        panic!("no cfg set");
-    }
+// build.rs
+fn main() {
+    // 1. 兼容tests7：设置TEST_FOO环境变量（原逻辑保留）
+    let timestamp = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap()
+        .as_secs();
+    println!("cargo:rustc-env=TEST_FOO={}", timestamp);
+
+    // 2. 兼容tests8：向Cargo输出指令，启用"pass"特性
+    println!("cargo:rustc-cfg=feature=\"pass\"");
 }