fix p256 flaky test (cosmos#350)

Author: songgaoye

tests/integration/precompiles/p256/test_integration.go

@@ -170,10 +170,11 @@ func TestPrecompileIntegrationTestSuite(t *testing.T, create network.CreateEvmAp
 
 						input = make([]byte, p256.VerifyInputLength)
 						copy(input[0:32], hash)
-						copy(input[32:64], rInt.Bytes())
-						copy(input[64:96], sInt.Bytes())
-						copy(input[96:128], privB.PublicKey.X.Bytes())
-						copy(input[128:160], privB.PublicKey.Y.Bytes())
+						// ALWAYS left-pad to 32 bytes:
+						copy(input[32:64], common.LeftPadBytes(rInt.Bytes(), 32))
+						copy(input[64:96], common.LeftPadBytes(sInt.Bytes(), 32))
+						copy(input[96:128], common.LeftPadBytes(privB.PublicKey.X.Bytes(), 32))
+						copy(input[128:160], common.LeftPadBytes(privB.PublicKey.Y.Bytes(), 32))
 						return input
 					},
 				),

tests/integration/precompiles/p256/test_p256.go

@@ -65,8 +65,9 @@ func (s *PrecompileTestSuite) TestRun() {
 
 				input := make([]byte, p256.VerifyInputLength)
 				copy(input[0:32], hash)
-				copy(input[32:64], rBz)
-				copy(input[64:96], sBz)
+				// ALWAYS left-pad to 32 bytes:
+				copy(input[32:64], common.LeftPadBytes(rBz, 32))
+				copy(input[64:96], common.LeftPadBytes(sBz, 32))
 				s.p256Priv.X.FillBytes(input[96:128])
 				s.p256Priv.Y.FillBytes(input[128:160])