coverage: Add `tests/coverage/assert-ne.rs`

This test extracts a fragment of `issue-84561.rs` that has historically proven
troublesome when trying to modify how spans are extracted from MIR.

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/coverage/assert-ne.rs b/tests/coverage/assert-ne.rs
new file mode 100644
index 00000000000..8a8fe089804
--- /dev/null
+++ b/tests/coverage/assert-ne.rs
@@ -0,0 +1,22 @@
+//@ edition: 2021
+
+use core::hint::black_box;
+
+#[derive(Debug, PartialEq)]
+struct Foo(u32);
+
+fn main() {
+    assert_ne!(
+        Foo(5), // Make sure this expression's span isn't lost.
+        if black_box(false) {
+            Foo(0) //
+        } else {
+            Foo(1) //
+        }
+    );
+    ()
+}
+
+// This test is a short fragment extracted from `issue-84561.rs`, highlighting
+// a particular span of code that can easily be lost if overlapping spans are
+// processed incorrectly.