Test glob pattern equivalent of --compilers (#3005)

This ensures that users can glob for multiple file extensions. That means two things:

- We could theoretically deprecate `--compilers` in favor of the other options (and globbing) for which it's shorthand.
- If we upgrade glob and the syntax to do this changes, we'll know due to the test failing.

test/integration/compiler-globbing.spec.js

@@ -0,0 +1,24 @@
+'use strict';
+
+var expect = require('expect.js');
+var exec = require('child_process').exec;
+var path = require('path');
+
+describe('globbing like --compilers', function () {
+  it('should find a file of each type', function (done) {
+    exec('"' + process.execPath + '" "' + path.join('bin', 'mocha') + '" -R json --require coffee-script/register --require test/compiler-fixtures/foo "test/compiler/*.@(coffee|foo)"', { cwd: path.join(__dirname, '..', '..') }, function (error, stdout) {
+      if (error && !stdout) { return done(error); }
+      var results = JSON.parse(stdout);
+      expect(results).to.have.property('tests');
+      var titles = [];
+      for (var index = 0; index < results.tests.length; index += 1) {
+        expect(results.tests[index]).to.have.property('fullTitle');
+        titles.push(results.tests[index].fullTitle);
+      }
+      expect(titles).to.contain('coffeescript should work');
+      expect(titles).to.contain('custom compiler should work');
+      expect(titles).to.have.length(2);
+      done();
+    });
+  });
+});