Add ERC20 test

Author: smoelius

integration/stylus/Uniswap/test/ERC20.sol

@@ -1,9 +1,13 @@
 pragma solidity =0.5.16;
 
-import '../UniswapV2ERC20.sol';
+import "../UniswapV2ERC20.sol";
 
 contract ERC20 is UniswapV2ERC20 {
-    constructor(uint _totalSupply) public {
+    bool inited;
+
+    function init(uint _totalSupply) public {
+        require(!inited);
         _mint(msg.sender, _totalSupply);
+        inited = true;
     }
 }

tests/stylus_tests/erc20.rs

@@ -0,0 +1,39 @@
+//! This test expects you to have a devnode running:
+//! <https://docs.arbitrum.io/run-arbitrum-node/run-nitro-dev-node>
+//!
+//! It also expects `cargo-stylus` and `cast` to be installed:
+//! - <https://github.com/OffchainLabs/cargo-stylus>
+//! - <https://book.getfoundry.sh/cast/>
+#![warn(clippy::pedantic)]
+
+use crate::{call, deploy, send, MUTEX};
+use std::path::PathBuf;
+
+#[test]
+fn erc20() {
+    let _lock = MUTEX.lock();
+    let (tempdir, address) = deploy(
+        PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("integration/stylus/Uniswap/test/ERC20.sol"),
+        "ERC20",
+        true,
+    )
+    .unwrap();
+    let dir = &tempdir;
+
+    let balance = concat!("1000000", "000000000000000000");
+
+    let stdout = call(dir, &address, ["totalSupply()(uint256)"]).unwrap();
+    println!("{}", stdout);
+    assert_eq!("0\n", stdout);
+
+    let stdout = send(dir, &address, ["init(uint256)", balance]).unwrap();
+    println!("{}", stdout);
+
+    // smoelius: Calling `init` a second time should revert.
+    let error = send(dir, &address, ["init(uint256)", balance]).unwrap_err();
+    println!("{:?}", error);
+
+    let stdout = call(dir, &address, ["totalSupply()(uint256)"]).unwrap();
+    println!("{}", stdout);
+    assert_eq!("1000000000000000000000000 [1e24]\n", stdout);
+}

tests/stylus_tests/mod.rs

@@ -3,6 +3,7 @@ mod arb_wasm;
 mod counter;
 mod create2;
 mod ecrecover;
+mod erc20;
 mod milestone_1;
 mod milestone_2;
 mod milestone_3;