coverage: Migrate tests/run-coverage into tests/coverage

tests/coverage/drop_trait.rs

@@ -0,0 +1,33 @@
+#![allow(unused_assignments)]
+// failure-status: 1
+
+struct Firework {
+    strength: i32,
+}
+
+impl Drop for Firework {
+    fn drop(&mut self) {
+        println!("BOOM times {}!!!", self.strength);
+    }
+}
+
+fn main() -> Result<(), u8> {
+    let _firecracker = Firework { strength: 1 };
+
+    let _tnt = Firework { strength: 100 };
+
+    if true {
+        println!("Exiting with error...");
+        return Err(1);
+    }
+
+    let _ = Firework { strength: 1000 };
+
+    Ok(())
+}
+
+// Expected program output:
+//   Exiting with error...
+//   BOOM times 100!!!
+//   BOOM times 1!!!
+//   Error: 1