dreddit-dapp/test/contract_spec.js

// our contract object to test
const DReddit = require('Embark/contracts/DReddit');

// contract methods we'll be testing
const {numPosts, create, vote, posts, canVote, getVote} = DReddit.methods;

// variables that will be updated in the tests
let accounts;
let postId;

// set up our config test parameters
config({
  contracts: {
    DReddit: {
      // would pass constructor args here if needed
    }
  }
}, (err, theAccounts) => {
  // this is the list of accounts our node / wallet controls.
  accounts = theAccounts;
});

// other test parameters
const ipfsHash = 'Qmc5gCcjYypU7y28oCALwfSvxCBskLuPKWpK4qpterKC7z';

// Embark exposes a global contract method as an alias
// for Mocha.describe
contract("DReddit contract", function () {
  this.timeout(0);

  it("should be able to create a post and receive it via contract event", async function () {    
    let receipt = await create(web3.utils.fromAscii(ipfsHash)).send();

    const event = receipt.events.NewPost;

    postId = event.returnValues.postId;
    assert.equal(web3.utils.toAscii(event.returnValues.description), ipfsHash);
  });

  it("post should have correct data", async function (){
    const post = await posts(postId).call();
    assert.equal(web3.utils.toAscii(post.description), ipfsHash);
    assert.equal(post.owner, accounts[0]);
  });

  it("one post should be registered", async function () {
    const n = await numPosts().call();
    assert.equal(n, 1);
  });

  it("should not be able to vote in an unexisting post", async function () {
    const userCanVote = await canVote(123).call();
    assert.equal(userCanVote, false);
  });

  it("should be able to vote in a post if account hasn't voted before", async function () {
    const userCanVote = await canVote(postId).call();
    assert.equal(userCanVote, true);
  });

  it("should be able to vote in a post", async function () {
    const receipt = await vote(postId, 1).send();
    const Vote = receipt.events.Vote;
    assert.equal(Vote.returnValues.voter, accounts[0]);
  });

  it("should't be able to vote twice", async function () {
    try {
      const receipt = await vote(postId, 1).send();
      assert.fail('should have reverted before');
    } catch (error){
        assert(error.message.search('revert') > -1, 'Revert should happen');
    }
  });

});