tests: add solidity test suites (#487)

* tests: add solidity test suite

* tests: remove require strings

* Update tests-solidity/init-test-node.sh

* Update tests-solidity/init-test-node.sh

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

tests-solidity/suites/basic/contracts/Counter.sol

@@ -0,0 +1,24 @@
+pragma solidity ^0.5.11;
+
+contract Counter {
+  uint256 counter = 0;
+  string internal constant ERROR_TOO_LOW = "COUNTER_TOO_LOW";
+  event Changed(uint256 counter);
+  event Added(uint256 counter);
+
+  function add() public {
+    counter++;
+    emit Added(counter);
+    emit Changed(counter);
+  }
+
+  function subtract() public {
+    require(counter > 0, ERROR_TOO_LOW);
+    counter--;
+    emit Changed(counter);
+  }
+
+  function getCounter() public view returns (uint256) {
+    return counter;
+  }
+}

tests-solidity/suites/basic/contracts/test/Migrations.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.4.22 <0.8.0;
+
+contract Migrations {
+  address public owner = msg.sender;
+  uint public last_completed_migration;
+
+  modifier restricted() {
+    require(
+      msg.sender == owner,
+      "This function is restricted to the contract's owner"
+    );
+    _;
+  }
+
+  function setCompleted(uint completed) public restricted {
+    last_completed_migration = completed;
+  }
+}