add test

Author: bishabosha

tests/run/i15399.check

@@ -0,0 +1,4 @@
+Expected failure when pass Tuple3 to TupleMirror(2):
+-  expected Product with 2 elements, got 3
+Expected failure when pass Tuple1 to TupleMirror(2):
+-  expected Product with 2 elements, got 1

tests/run/i15399.scala

@@ -0,0 +1,15 @@
+@main def Test =
+  val tup2Mirror = summon[scala.deriving.Mirror.Of[(Int, Int)]]
+  try
+    val tup2a: (Int, Int) = tup2Mirror.fromProduct((1, 2, 3)) // fails silently and creates (1, 2)
+    println(tup2a)  // should be unreachable
+  catch case err: IllegalArgumentException =>
+    println("Expected failure when pass Tuple3 to TupleMirror(2):")
+    println(s"-  ${err.getMessage}")
+
+  try
+    val tup2b: (Int, Int) = tup2Mirror.fromProduct(Tuple(1)) // crashes with index out of bounds
+    println(tup2b) // should be unreachable
+  catch case err: IllegalArgumentException =>
+    println("Expected failure when pass Tuple1 to TupleMirror(2):")
+    println(s"-  ${err.getMessage}")