add test case for previous commit

test/behavior.zig

@@ -40,6 +40,7 @@ comptime {
     _ = @import("cases/this.zig");
     _ = @import("cases/try.zig");
     _ = @import("cases/undefined.zig");
+    _ = @import("cases/union.zig");
     _ = @import("cases/var_args.zig");
     _ = @import("cases/void.zig");
     _ = @import("cases/while.zig");

test/cases/union.zig

@@ -0,0 +1,33 @@
+const assert = @import("std").debug.assert;
+
+const Value = enum {
+    Int: u64,
+    Array: [9]u8,
+};
+
+const Agg = struct {
+    val1: Value,
+    val2: Value,
+};
+
+const v1 = Value.Int { 1234 };
+const v2 = Value.Array { []u8{3} ** 9 };
+
+const err = (%Agg)(Agg {
+    .val1 = v1,
+    .val2 = v2,
+});
+
+const array = []Value { v1, v2, v1, v2};
+
+
+test "unions embedded in aggregate types" {
+    switch (array[1]) {
+        Value.Array => |arr| assert(arr[4] == 3),
+        else => unreachable,
+    }
+    switch((%%err).val1) {
+        Value.Int => |x| assert(x == 1234),
+        else => unreachable,
+    }
+}