Add test for returning structs from functions

Author: czgdp1807

integration_tests/structs_11.py

@@ -0,0 +1,18 @@
+from ltypes import i32, f64, dataclass
+
+@dataclass
+class A:
+    x: i32
+    y: f64
+
+def f(x_: i32, y_: f64) -> A:
+    a_struct: A = A(x_, y_)
+    return a_struct
+
+def test_struct_return():
+    b: A = f(0, 1.0)
+    print(b.x, b.y)
+    assert b.x == 0
+    assert b.y == 1.0
+
+test_struct_return()