Python contract wrappers (#1721)

python-packages/contract_wrappers/test/test_erc20_wrapper.py

@@ -0,0 +1,80 @@
+"""Tests for ERC20Token wrapper."""
+
+from decimal import Decimal
+
+import pytest
+
+from zero_ex.contract_wrappers import ERC20Token, TxParams
+
+
+MAX_ALLOWANCE = int("{:.0f}".format(Decimal(2) ** 256 - 1))
+
+
+@pytest.fixture(scope="module")
+def erc20_wrapper(ganache_provider):
+    """Get an instance of ERC20Token wrapper class for testing."""
+    return ERC20Token(ganache_provider)
+
+
+def test_erc20_wrapper__balance_of(
+    accounts,
+    erc20_wrapper,  # pylint: disable=redefined-outer-name
+    weth_address,
+    weth_instance,  # pylint: disable=redefined-outer-name
+):
+    """Test getting baance of an account for an ERC20 token."""
+    acc1_original_weth_balance = erc20_wrapper.balance_of(
+        weth_address, accounts[0]
+    )
+    acc2_original_weth_balance = erc20_wrapper.balance_of(
+        weth_address, accounts[1]
+    )
+
+    expected_difference = 1 * 10 ** 18
+
+    weth_instance.functions.deposit().transact(
+        {"from": accounts[0], "value": expected_difference}
+    )
+    weth_instance.functions.deposit().transact(
+        {"from": accounts[1], "value": expected_difference}
+    )
+    acc1_weth_balance = erc20_wrapper.balance_of(weth_address, accounts[0])
+    acc2_weth_balance = erc20_wrapper.balance_of(weth_address, accounts[1])
+
+    assert (
+        acc1_weth_balance - acc1_original_weth_balance == expected_difference
+    )
+    assert (
+        acc2_weth_balance - acc2_original_weth_balance == expected_difference
+    )
+
+
+def test_erc20_wrapper__approve(
+    accounts,
+    erc20_proxy_address,
+    erc20_wrapper,  # pylint: disable=redefined-outer-name
+    weth_address,  # pylint: disable=redefined-outer-name
+):
+    """Test approving one account to spend balance from another account."""
+    erc20_wrapper.approve(
+        weth_address,
+        erc20_proxy_address,
+        MAX_ALLOWANCE,
+        tx_params=TxParams(from_=accounts[0]),
+    )
+    erc20_wrapper.approve(
+        weth_address,
+        erc20_proxy_address,
+        MAX_ALLOWANCE,
+        tx_params=TxParams(from_=accounts[1]),
+    )
+
+    acc_1_weth_allowance = erc20_wrapper.allowance(
+        weth_address, accounts[0], erc20_proxy_address
+    )
+    acc_2_weth_allowance = erc20_wrapper.allowance(
+        weth_address, accounts[1], erc20_proxy_address
+    )
+
+    assert acc_1_weth_allowance == MAX_ALLOWANCE
+    assert acc_2_weth_allowance == MAX_ALLOWANCE