Add a new perf test

tests/perf/btreeset/insert_multi/Cargo.toml

@@ -0,0 +1,11 @@
+# Copyright Kani Contributors
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+
+[package]
+name = "insert_multi"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tests/perf/btreeset/insert_multi/expected

@@ -0,0 +1,2 @@
+** 2 of 2 cover properties satisfied
+VERIFICATION:- SUCCESSFUL

tests/perf/btreeset/insert_multi/src/main.rs

@@ -0,0 +1,26 @@
+// Copyright Kani Contributors
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! This test checks the performance of pushing multiple non-det elements onto a
+//! `BtreeSet`
+
+use kani::cover;
+use std::collections::BTreeSet;
+
+#[kani::proof]
+#[kani::unwind(3)]
+#[kani::solver(cadical)]
+fn insert_multi() {
+    const N: usize = 2;
+    let mut set: BTreeSet<i32> = BTreeSet::new();
+    for _i in 0..N {
+        set.insert(kani::any());
+    }
+    assert!(!set.is_empty());
+    // all elements are the same
+    cover!(set.len() == 1);
+    // two unique elements
+    cover!(set.len() == 2);
+}
+
+fn main() {}