Add tests for 'useless' (but valid) expressions

It's unclear why someone would do these things, but they're
valid solidity, so we should support them...

test/expressions.js

@@ -0,0 +1,32 @@
+var solc = require('solc');
+var getInstrumentedVersion = require('./../instrumentSolidity.js');
+var util = require('./util/util.js');
+const CoverageMap = require('./../coverageMap');
+const path = require('path');
+const vm = require('./util/vm');
+const assert = require('assert');
+
+/**
+ * NB: passing '1' to solc as an option activates the optimiser
+ * NB: solc will throw if there is a compilation error, causing the test to fail
+ *     and passing the error to mocha.
+ */
+describe('generic expressions', function(){
+  const filePath = path.resolve('./test.sol');
+  const pathPrefix = './';
+
+  it('should compile after instrumenting a single binary expression', function(){
+    var contract = util.getCode('expressions/single-binary-expression.sol');
+    var info = getInstrumentedVersion(contract, filePath, true);
+    var output = solc.compile(info.contract, 1);
+    util.report(output.errors);
+  })
+
+  it('should compile after instrumenting a new expression', function(){
+    var contract = util.getCode('expressions/new-expression.sol');
+    var info = getInstrumentedVersion(contract, filePath, true);
+    var output = solc.compile(info.contract, 1);
+    util.report(output.errors);
+  })
+
+})

test/sources/expressions/new-expression.sol

@@ -0,0 +1,12 @@
+pragma solidity ^0.4.3;
+
+contract Test {
+    function a(uint x) {
+      new Test2(x);
+    }
+}
+contract Test2 {
+    function Test2(uint x) {
+      x+1;
+    }
+}

test/sources/expressions/single-binary-expression.sol

@@ -0,0 +1,7 @@
+pragma solidity ^0.4.3;
+
+contract Test {
+    function a(uint x) {
+      x+1;
+    }
+}