test(plonky2_prove): Add tests for casts from lower signed type bit l…

…ength to higher

test_programs/plonky2_prove_failure/signed_casts/Nargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "signed_casts"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.27.0"
+
+[dependencies]
+

test_programs/plonky2_prove_failure/signed_casts/Prover.toml

@@ -0,0 +1,3 @@
+x = [ -128, 127 ]
+y = [ -128, 127 ]
+z = [ -128, 127 ]

test_programs/plonky2_prove_failure/signed_casts/src/main.nr

@@ -0,0 +1,10 @@
+fn main(x: [i8; 2], y: [i16; 2], z: [i32; 2]) {
+    for i in 0..1 {
+        //  i8 -> i16
+        assert(x[i] as i16 == y[i]);
+        //  i8 -> i32
+        assert(x[i] as i32 == z[i]);
+        // i16 -> i32
+        assert(y[i] as i32 == z[i]);
+    }
+}