1 files changed, 63 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/manual_string_new.rs b/src/tools/clippy/tests/ui/manual_string_new.rs
new file mode 100644
index 000000000..6bfc52fb1
--- /dev/null
+++ b/src/tools/clippy/tests/ui/manual_string_new.rs
@@ -0,0 +1,63 @@
+// run-rustfix
+
+#![warn(clippy::manual_string_new)]
+
+macro_rules! create_strings_from_macro {
+    // When inside a macro, nothing should warn to prevent false positives.
+    ($some_str:expr) => {
+        let _: String = $some_str.into();
+        let _ = $some_str.to_string();
+    };
+}
+
+fn main() {
+    // Method calls
+    let _ = "".to_string();
+    let _ = "no warning".to_string();
+
+    let _ = "".to_owned();
+    let _ = "no warning".to_owned();
+
+    let _: String = "".into();
+    let _: String = "no warning".into();
+
+    let _: SomeOtherStruct = "no warning".into();
+    let _: SomeOtherStruct = "".into(); // No warning too. We are not converting into String.
+
+    // Calls
+    let _ = String::from("");
+    let _ = <String>::from("");
+    let _ = String::from("no warning");
+    let _ = SomeOtherStruct::from("no warning");
+    let _ = SomeOtherStruct::from(""); // Again: no warning.
+
+    let _ = String::try_from("").unwrap();
+    let _ = String::try_from("no warning").unwrap();
+    let _ = String::try_from("no warning").expect("this should not warn");
+    let _ = SomeOtherStruct::try_from("no warning").unwrap();
+    let _ = SomeOtherStruct::try_from("").unwrap(); // Again: no warning.
+
+    let _: String = From::from("");
+    let _: String = From::from("no warning");
+    let _: SomeOtherStruct = From::from("no warning");
+    let _: SomeOtherStruct = From::from(""); // Again: no warning.
+
+    let _: String = TryFrom::try_from("").unwrap();
+    let _: String = TryFrom::try_from("no warning").unwrap();
+    let _: String = TryFrom::try_from("no warning").expect("this should not warn");
+    let _: String = TryFrom::try_from("").expect("this should warn");
+    let _: SomeOtherStruct = TryFrom::try_from("no_warning").unwrap();
+    let _: SomeOtherStruct = TryFrom::try_from("").unwrap(); // Again: no warning.
+
+    // Macros (never warn)
+    create_strings_from_macro!("");
+    create_strings_from_macro!("Hey");
+}
+
+struct SomeOtherStruct {}
+
+impl From<&str> for SomeOtherStruct {
+    fn from(_value: &str) -> Self {
+        Self {}
+    }
+}