Add functions with multiple arguments to import macro, add test cases

plugins/test_plugin/src/lib.rs

@@ -35,10 +35,29 @@ pub fn print(string: String) {
     eprintln!("to stderr: {}", string);
 }
 
-// #[import]
-// fn mystery_number(input: u32) -> u32;
+#[import]
+fn mystery_number(input: u32) -> u32;
 
-// #[export]
-// pub fn and_back(secret: u32) -> u32 {
-//     mystery_number(secret)
-// }
+#[export]
+pub fn and_back(secret: u32) -> u32 {
+    mystery_number(secret)
+}
+
+#[import]
+fn import_noop() -> ();
+
+#[import]
+fn import_identity(i: u32) -> u32;
+
+#[import]
+fn import_swap(a: u32, b: u32) -> (u32, u32);
+
+#[export]
+pub fn imports(x: u32) -> u32 {
+    let a = import_identity(7);
+    import_noop();
+    let (b, c) = import_swap(a, x);
+    assert_eq!(a, c);
+    assert_eq!(x, b);
+    a + b // should be 7 + x
+}