Tests for cache system

wasmtime-environ/tests/cache_fail_calling_init_twice.rs

@@ -0,0 +1,10 @@
+use tempfile;
+use wasmtime_environ::cache_conf;
+
+#[test]
+#[should_panic]
+fn test_fail_calling_init_twice() {
+    let dir = tempfile::tempdir().expect("Can't create temporary directory");
+    cache_conf::init(true, Some(dir.path()));
+    cache_conf::init(true, Some(dir.path()));
+}