1 files changed, 40 insertions, 0 deletions
diff --git a/tests/ui/lint/missing-debug-implementations-lint.rs b/tests/ui/lint/missing-debug-implementations-lint.rs
new file mode 100644
index 00000000000..8a93f052f9c
--- /dev/null
+++ b/tests/ui/lint/missing-debug-implementations-lint.rs
@@ -0,0 +1,40 @@
+//! Test the `missing_debug_implementations` lint that warns about public types without Debug.
+//!
+//! See https://github.com/rust-lang/rust/issues/20855
+
+//@ compile-flags: --crate-type lib
+#![deny(missing_debug_implementations)]
+#![allow(unused)]
+
+use std::fmt;
+
+pub enum A {} //~ ERROR type does not implement `Debug`
+
+#[derive(Debug)]
+pub enum B {}
+
+pub enum C {}
+impl fmt::Debug for C {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        Ok(())
+    }
+}
+
+pub struct Foo; //~ ERROR type does not implement `Debug`
+
+#[derive(Debug)]
+pub struct Bar;
+
+pub struct Baz;
+impl fmt::Debug for Baz {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        Ok(())
+    }
+}
+
+// Private types should not trigger the lint
+struct PrivateStruct;
+enum PrivateEnum {}
+
+#[derive(Debug)]
+pub struct GenericType<T>(T);