WebIDL: Handle Invalid Enum Returns (#477)

* move ImportEnum attributes to a property

* borrow from_js_value argument

* make WebIDL enums non-exhaustive

* add more tests for WebIDL enums

crates/webidl/tests/all/enums.rs

@@ -1,23 +1,25 @@
 use super::project;
 
+static SHAPE_IDL: &'static str = r#"
+    enum ShapeType { "circle", "square" };
+    
+    [Constructor(ShapeType kind)]
+    interface Shape {
+        [Pure]
+        boolean isSquare();
+
+        [Pure]
+        boolean isCircle();
+
+        [Pure]
+        ShapeType getShape();
+    };
+"#;
+
 #[test]
 fn top_level_enum() {
     project()
-        .file(
-            "shape.webidl",
-            r#"
-            enum ShapeType { "circle", "square" };
-            
-            [Constructor(ShapeType kind)]
-            interface Shape {
-                [Pure]
-                boolean isSquare();
-
-                [Pure]
-                boolean isCircle();
-            };
-        "#,
-        )
+        .file("shape.webidl", SHAPE_IDL)
         .file(
             "shape.mjs",
             r#"
@@ -33,6 +35,10 @@ fn top_level_enum() {
                 isCircle() {
                     return this.kind === 'circle';
                 }
+
+                getShape() {
+                    return this.kind;
+                }
             }
             "#,
         )
@@ -62,3 +68,112 @@ fn top_level_enum() {
         )
         .test();
 }
+
+#[test]
+fn valid_enum_return() {
+    project()
+        .file("shape.webidl", SHAPE_IDL)
+        .file(
+            "shape.mjs",
+            r#"
+            export class Shape {
+                constructor(kind) {
+                    this.kind = kind;
+                }
+
+                isSquare() {
+                    return this.kind === 'square';
+                }
+
+                isCircle() {
+                    return this.kind === 'circle';
+                }
+
+                getShape() {
+                    return this.kind;
+                }
+            }
+            "#,
+        )
+        .file(
+            "src/lib.rs",
+            r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            pub mod shape;
+
+            use shape::{Shape, ShapeType};
+
+            #[wasm_bindgen]
+            pub fn test() {
+                let circle = Shape::new(ShapeType::Circle).unwrap();
+                let square = Shape::new(ShapeType::Square).unwrap();
+                assert!(circle.is_circle());
+                assert!(!circle.is_square());
+                assert_eq!(circle.get_shape(), ShapeType::Circle);
+                assert!(square.is_square());
+                assert!(!square.is_circle());
+                assert_eq!(square.get_shape(), ShapeType::Square);
+            }
+        "#,
+        )
+        .test();
+}
+
+#[test]
+fn invalid_enum_return() {
+    project()
+        .file("shape.webidl", SHAPE_IDL)
+        .file(
+            "shape.mjs",
+            r#"
+            export class Shape {
+                constructor(kind) {
+                    this.kind = 'triangle'; // <-- invalid ShapeType
+                }
+
+                isSquare() {
+                    return this.kind === 'square';
+                }
+
+                isCircle() {
+                    return this.kind === 'circle';
+                }
+
+                getShape() {
+                    return this.kind;
+                }
+            }
+            "#,
+        )
+        .file(
+            "src/lib.rs",
+            r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            pub mod shape;
+
+            use shape::{Shape, ShapeType};
+
+            #[wasm_bindgen]
+            pub fn test() {
+                let actually_a_triangle = Shape::new(ShapeType::Circle).unwrap();
+                assert!(!actually_a_triangle.is_circle());
+                assert!(!actually_a_triangle.is_square());
+                match actually_a_triangle.get_shape() {
+                    ShapeType::Circle | ShapeType::Square => assert!(false),
+                    _ => {} // Success
+                };
+            }
+        "#,
+        )
+        .test();
+}