feat(package): export the package version

As kerberos can be used as an optional dependency, we expose the
version at api level to allow third party libraries to consume the
version number easily.

It includes a test that verifies what's being exported.

index.js

@@ -8,6 +8,8 @@ module.exports = kerberos;
 // Support legacy versions of the mongodb driver which expect this export
 module.exports.Kerberos = kerberos;
 
+module.exports.version = require('./package.json').version;
+
 // Set up the auth processes
 module.exports.processes = {
   MongoAuthProcess: require('./lib/auth_processes/mongodb').MongoAuthProcess

test/exports_tests.js

@@ -0,0 +1,40 @@
+'use strict';
+
+const chai = require('chai');
+const expect = chai.expect;
+const api = require('../index');
+
+describe('module', function () {
+  it('should export version', function () {
+    expect(api.version).to.be.a('string');
+    expect(api.version).to.match(/\d+\.\d+/);
+  });
+
+  it('should export flags and ids', function () {
+    [
+      api.GSS_C_DELEG_FLAG,
+      api.GSS_C_MUTUAL_FLAG,
+      api.GSS_C_REPLAY_FLAG,
+      api.GSS_C_SEQUENCE_FLAG,
+      api.GSS_C_CONF_FLAG,
+      api.GSS_C_INTEG_FLAG,
+      api.GSS_C_ANON_FLAG,
+      api.GSS_C_PROT_READY_FLAG,
+      api.GSS_C_TRANS_FLAG,
+      api.GSS_C_NO_OID,
+      api.GSS_MECH_OID_KRB5,
+      api.GSS_MECH_OID_SPNEGO
+    ].forEach(flag => expect(flag).to.be.a('number'));
+  });
+
+  it('should export functions', function () {
+    expect(api.initializeClient).to.be.a('function');
+    expect(api.initializeServer).to.be.a('function');
+    expect(api.principalDetails).to.be.a('function');
+    expect(api.checkPassword).to.be.a('function');
+  });
+
+  it('should export Kerberos', () => {
+    expect(api.Kerberos).to.be.an('object');
+  });
+});