start with test runner

full-tests/to-empty-main/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "to-empty-main"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

full-tests/to-empty-main/src/main.rs

@@ -0,0 +1,12 @@
+use std::collecions::HashMap;
+
+/// ~REQUIRE-DELETED
+fn user(map: HashMap<(), ()>) {
+    map.insert((), ());
+}
+
+/// ~MINIMIZE-ROOT main
+fn main() {
+    let map = HashMap::new();
+    user(map);
+}