Add tests for rational and scientific notation constants

tests/constant_folding_rational.sol

@@ -0,0 +1,7 @@
+contract C {
+    uint256 constant a = 2.5 + 7 + 0.5;
+    int128 b = 6 / 3.0;
+    int64 constant c = 5 * 0.5 + 0.5;
+    int256 d = 1e3 + 5E2;
+    uint256 e = 2 ** 255;
+}

tests/test_constant_folding.py

@@ -0,0 +1,30 @@
+from slither import Slither
+from slither.visitors.expression.constants_folding import ConstantFolding
+
+
+def test_constant_folding_unary():
+    Slither("./tests/constant_folding_unary.sol")
+
+def test_constant_folding_rational():
+    s = Slither("./tests/constant_folding_rational.sol")
+    contract = s.get_contract_from_name("C")[0]
+
+    variable_a = contract.get_state_variable_from_name("a")
+    assert str(variable_a.type) == "uint256"
+    assert str(ConstantFolding(variable_a.expression, "uint256").result()) == "10"
+
+    variable_b = contract.get_state_variable_from_name("b")
+    assert str(variable_b.type) == "int128"
+    assert str(ConstantFolding(variable_b.expression, "int128").result()) == "2"
+
+    variable_c = contract.get_state_variable_from_name("c")
+    assert str(variable_c.type) == "int64"
+    assert str(ConstantFolding(variable_c.expression, "int64").result()) == "3"
+
+    variable_d = contract.get_state_variable_from_name("d")
+    assert str(variable_d.type) == "int256"
+    assert str(ConstantFolding(variable_d.expression, "int256").result()) == "1500"
+
+    variable_e = contract.get_state_variable_from_name("e")
+    assert str(variable_e.type) == "uint256"
+    assert str(ConstantFolding(variable_e.expression, "uint256").result()) == "57896044618658097711785492504343953926634992332820282019728792003956564819968"

tests/test_constant_folding_unary.py

@@ -1,5 +0,0 @@
-from slither import Slither
-
-
-def test_constant_folding_unary():
-    Slither("./tests/constant_folding_unary.sol")