solution

lib-index.js

// Load modules
var Hoek = require('hoek');
var Joi = require('joi');

var pkg = require('../package.json');

// Declare internals
var internals = {
    schema: {
        path: Joi.string().optional().default('/hapi-info')
    }
};


internals.generateHapiInfo = function() {

    var self = this;

    var payload = {
        server: {
            node: process.version,
            hapi: self._sources[0].server.version,
            host: self.info.host,
            port: self.info.port,
            uri: self.info.uri
        },
        plugins: []
    };
    
    for (var i = 0, il = self._sources.length; i < il; ++i) {
        var source = self._sources[i];
        if (!source._registrations) {
            continue;
        }
        var registrations = Object.keys(source._registrations);

        for (var j = 0, ij = registrations.length; j < ij; ++j) {
            var pluginKey = registrations[j];
            var plugin = source._registrations[pluginKey];
            payload.plugins.push({ name: plugin.name, version: plugin.version });
        }
    }

    return payload;
};


exports.register = function (server, options, next) {

    var validation = Joi.validate(options, internals.schema);
    Hoek.assert(validation.error === null, 'Invalid option(s)');
    options = validation.value;

    server.expose('info', internals.generateHapiInfo.bind(server));

    server.route({
        method: 'GET',
        path: options.path,
        handler: function (request, reply) {

            var payload = server.plugins[pkg.name].info();
            return reply(payload);
        }
    });

    next();
};


exports.register.attributes = {
    pkg: pkg
};

test-index.js

// Load modules

var Code = require('code');
var Glue = require('glue');
var Hapi = require('hapi');
var Lab = require('lab');


// Test shortcuts

var lab = exports.lab = Lab.script();
var expect = Code.expect;
var describe = lab.describe;
var it = lab.test;


var internals = {};

internals.prepareServer = function (options, callback) {

    var server = new Hapi.Server();

    var manifest = {
        plugins: [
            { '../': options },
            { './plugins/blah.js': null },
            { './plugins/main.js': null }
        ]
    };

    Glue.compose(manifest, { relativeTo: __dirname }, function (err, server) {

        expect(err).to.not.exist();
        return callback(err, server);
    });
};

describe('routes', function () {

    it('prints plugin and server information', function (done) {

        internals.prepareServer({}, function (err, server) {

            server.inject('/hapi-info', function (res) {


                var result = {
                    server: {
                        node: process.version,
                        hapi: '8.8.1',
                        host: server.info.host,
                        port: server.info.port,
                        uri: server.info.uri
                    },
                    plugins: [{
                        name: 'hapi-info',
                        version: require('./../package.json').version
                    },
                    {
                        name: 'blah',
                        version: '1.2.3'
                    },
                    {
                        name: 'main',
                        version: '0.1.1'
                    }]
                };
                expect(res.result).to.deep.equal(result);
                done();
            });
        });
    });

    it('prints plugin and server to a different path', function (done) {

        internals.prepareServer({ path: '/foo' }, function (err, server) {

            server.inject('/foo', function (res) {


                var result = {
                    server: {
                        node: process.version,
                        hapi: '8.8.1',
                        host: server.info.host,
                        port: server.info.port,
                        uri: server.info.uri
                    },
                    plugins: [{
                        name: 'hapi-info',
                        version: require('./../package.json').version
                    },
                    {
                        name: 'blah',
                        version: '1.2.3'
                    },
                    {
                        name: 'main',
                        version: '0.1.1'
                    }]
                };
                expect(res.result).to.deep.equal(result);
                done();
            });
        });
    });

    it('prints plugin and server info using expose', function (done) {

        internals.prepareServer({ path: '/foo' }, function (err, server) {

            var info = server.plugins['hapi-info'].info();

            var result = {
                server: {
                    node: process.version,
                    hapi: '8.8.1',
                    host: server.info.host,
                    port: server.info.port,
                    uri: server.info.uri
                },
                plugins: [{
                    name: 'hapi-info',
                    version: require('./../package.json').version
                },
                {
                    name: 'blah',
                    version: '1.2.3'
                },
                {
                    name: 'main',
                    version: '0.1.1'
                }]
            };
            expect(info).to.deep.equal(result);
            done();
        });
    });

});