fix incorrect max calculation in uint256 domain (#775)

* fix incorrect max calculation in  uint256 domain

* add test for max uint256

* fixed negative test

internal/sql/pg/sql.go

@@ -66,11 +66,13 @@ END$$;`
 
 	sqlCreateUUIDExtension = `CREATE EXTENSION IF NOT EXISTS "uuid-ossp";`
 
-	// have to run this in a DO block because you cannot do CREATE DOMAIN IF NOT EXISTS
+	// have to run this in a DO block because you cannot do CREATE DOMAIN IF NOT EXISTS.
+	// We have to hard-code the string and then convert to numeric instead of using 2^256-1,
+	// because Postgres will not precisely evaluate 2^256-1.
 	sqlCreateUint256Domain = `
 	DO $$ BEGIN
 		CREATE DOMAIN uint256 AS NUMERIC(78)
-		CHECK (VALUE >= 0 AND VALUE < 2^256)
+		CHECK (VALUE >= 0 AND VALUE <= '115792089237316195423570985008687907853269984665640564039457584007913129639935'::NUMERIC(78))
 		CHECK (SCALE(VALUE) = 0);
 	EXCEPTION
 		WHEN duplicate_object THEN null;

test/specifications/types.go

@@ -142,7 +142,8 @@ func testDecimal(ctx context.Context, t *testing.T, execute ProcedureDSL, dbid s
 
 func testUint256(ctx context.Context, t *testing.T, execute ProcedureDSL, dbid string, callType string) {
 	// execute store
-	uint256 := types.Uint256FromInt(123)
+	uint256, err := types.Uint256FromString("115792089237316195423570985008687907853269984665640564039457584007913129639935") // max uint256
+	require.NoError(t, err)
 	uint256Arr := []any{types.Uint256FromInt(456), types.Uint256FromInt(789)}
 
 	signMu.Lock()
@@ -167,6 +168,13 @@ func testUint256(ctx context.Context, t *testing.T, execute ProcedureDSL, dbid s
 		}
 	}
 	assert.Equal(t, 1, count)
+
+	// test that greater than max uint256 is not allowed.
+	// we pass it as a string since our uint256 type will also error if it exceeds max uint256
+	res, err = execute.Execute(ctx, dbid, callType+"_store_uint256s", []any{"115792089237316195423570985008687907853269984665640564039457584007913129639936", uint256Arr})
+	require.NoError(t, err)
+
+	ExpectTxfail(t, execute, ctx, res)
 }
 
 func testText(ctx context.Context, t *testing.T, execute ProcedureDSL, dbid string, callType string) {