1 files changed, 60 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/unnecessary_box_returns.rs b/src/tools/clippy/tests/ui/unnecessary_box_returns.rs
new file mode 100644
index 000000000..fe60d9297
--- /dev/null
+++ b/src/tools/clippy/tests/ui/unnecessary_box_returns.rs
@@ -0,0 +1,60 @@
+#![warn(clippy::unnecessary_box_returns)]
+
+trait Bar {
+    // lint
+    fn baz(&self) -> Box<usize>;
+}
+
+pub struct Foo {}
+
+impl Bar for Foo {
+    // don't lint: this is a problem with the trait, not the implementation
+    fn baz(&self) -> Box<usize> {
+        Box::new(42)
+    }
+}
+
+impl Foo {
+    fn baz(&self) -> Box<usize> {
+        // lint
+        Box::new(13)
+    }
+}
+
+// lint
+fn bxed_usize() -> Box<usize> {
+    Box::new(5)
+}
+
+// lint
+fn _bxed_foo() -> Box<Foo> {
+    Box::new(Foo {})
+}
+
+// don't lint: this is exported
+pub fn bxed_foo() -> Box<Foo> {
+    Box::new(Foo {})
+}
+
+// don't lint: str is unsized
+fn bxed_str() -> Box<str> {
+    "Hello, world!".to_string().into_boxed_str()
+}
+
+// don't lint: function contains the word, "box"
+fn boxed_usize() -> Box<usize> {
+    Box::new(7)
+}
+
+// don't lint: this has an unspecified return type
+fn default() {}
+
+// don't lint: this doesn't return a Box
+fn string() -> String {
+    String::from("Hello, world")
+}
+
+fn main() {
+    // don't lint: this is a closure
+    let a = || -> Box<usize> { Box::new(5) };
+}