add tests

crates/ide-assists/src/handlers/generate_new.rs

@@ -123,6 +123,97 @@ mod tests {
 
     use super::*;
 
+    #[test]
+    fn test_generate_new_with_zst_fields() {
+        check_assist(
+            generate_new,
+            r#"
+struct Empty;
+
+struct Foo { empty: Empty $0}
+"#,
+            r#"
+struct Empty;
+
+struct Foo { empty: Empty }
+
+impl Foo {
+    fn $0new() -> Self { Self { empty: Empty } }
+}
+"#,
+        );
+        check_assist(
+            generate_new,
+            r#"
+struct Empty;
+
+struct Foo { baz: String, empty: Empty $0}
+"#,
+            r#"
+struct Empty;
+
+struct Foo { baz: String, empty: Empty }
+
+impl Foo {
+    fn $0new(baz: String) -> Self { Self { baz, empty: Empty } }
+}
+"#,
+        );
+        check_assist(
+            generate_new,
+            r#"
+enum Empty { Bar }
+
+struct Foo { empty: Empty $0}
+"#,
+            r#"
+enum Empty { Bar }
+
+struct Foo { empty: Empty }
+
+impl Foo {
+    fn $0new() -> Self { Self { empty: Empty::Bar } }
+}
+"#,
+        );
+
+        // make sure the assist only works on unit variants
+        check_assist(
+            generate_new,
+            r#"
+struct Empty {}
+
+struct Foo { empty: Empty $0}
+"#,
+            r#"
+struct Empty {}
+
+struct Foo { empty: Empty }
+
+impl Foo {
+    fn $0new(empty: Empty) -> Self { Self { empty } }
+}
+"#,
+        );
+        check_assist(
+            generate_new,
+            r#"
+enum Empty { Bar {} }
+
+struct Foo { empty: Empty $0}
+"#,
+            r#"
+enum Empty { Bar {} }
+
+struct Foo { empty: Empty }
+
+impl Foo {
+    fn $0new(empty: Empty) -> Self { Self { empty } }
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_generate_new() {
         check_assist(

crates/ide-diagnostics/src/handlers/missing_fields.rs

@@ -345,6 +345,92 @@ fn test_fn() {
         );
     }
 
+    #[test]
+    fn test_fill_struct_zst_fields() {
+        check_fix(
+            r#"
+struct Empty;
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct {$0};
+}
+"#,
+            r#"
+struct Empty;
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct { one: 0, two: Empty };
+}
+"#,
+        );
+        check_fix(
+            r#"
+enum Empty { Foo };
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct {$0};
+}
+"#,
+            r#"
+enum Empty { Foo };
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct { one: 0, two: Empty::Foo };
+}
+"#,
+        );
+
+        // make sure the assist doesn't fill non Unit variants
+        check_fix(
+            r#"
+struct Empty {};
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct {$0};
+}
+"#,
+            r#"
+struct Empty {};
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct { one: 0, two: todo!() };
+}
+"#,
+        );
+        check_fix(
+            r#"
+enum Empty { Foo {} };
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct {$0};
+}
+"#,
+            r#"
+enum Empty { Foo {} };
+
+struct TestStruct { one: i32, two: Empty }
+
+fn test_fn() {
+    let s = TestStruct { one: 0, two: todo!() };
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_fill_struct_fields_self() {
         check_fix(