Update tests for solc 0.7.x (#582)

Author: cgewecke

package.json

@@ -57,8 +57,8 @@
     "hardhat-gas-reporter": "^1.0.1",
     "mocha": "5.2.0",
     "nyc": "^14.1.1",
-    "solc": "^0.5.10",
-    "truffle": "5.0.31",
+    "solc": "^0.7.5",
+    "truffle": "5.1.43",
     "truffle-config": "^1.1.18"
   }
 }

test/integration/generic/assets/SimpleError.sol

@@ -1,5 +1,5 @@
 // This contract should throw a parse error in instrumentSolidity.js
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 contract SimpleError {
     uint x = 0;

test/integration/generic/contracts/Migrations.sol

@@ -1,4 +1,4 @@
-pragma solidity >=0.4.22 <0.6.0;
+pragma solidity >=0.4.22 <0.8.0;
 
 
 contract Migrations {

test/integration/projects/contract-subfolders/contracts/A/ContractA2.sol

@@ -1,9 +1,8 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 import "./../B/ContractB2.sol";
 
 contract ContractA is ContractB {
-  uint x;
   constructor() public {
   }
 

test/integration/projects/contract-subfolders/contracts/B/ContractB2.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 
 contract ContractB {

test/integration/projects/contract-subfolders/hardhat.config.js

@@ -8,7 +8,7 @@ module.exports={
     }
   },
   solidity: {
-    version: "0.5.15"
+    version: "0.7.3"
   },
   paths: {
     sources: './contracts/A'

test/integration/projects/ganache-solcoverjs/contracts/ContractA.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 
 contract ContractA {

test/integration/projects/ganache-solcoverjs/contracts/ContractB.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 
 contract ContractB {

test/integration/projects/ganache-solcoverjs/contracts/ContractC.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.7.0;
 
 
 contract ContractC {

test/integration/projects/ganache-solcoverjs/hardhat.config.js

@@ -3,7 +3,7 @@ require(__dirname + "/../plugins/nomiclabs.plugin");
 
 module.exports = {
   solidity: {
-    version: "0.5.15"
+    version: "0.7.3"
   },
   networks: {
     coverage: {