55 lines
2.5 KiB
Markdown
55 lines
2.5 KiB
Markdown
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## Unit testing
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Now that we finished coding our contract, we can proceed to build unit testing for it. Embark generates javascript code for interacting with the contract `DReddit` and will make it possible to use it from both our unit tests and our dApp. There are some tests already implemented in `./test/contract_spec.js`, but we will add a couple that illustrate the most common test case scenarios
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### We should be able to create a post and receive it via contract event
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```
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let receipt = await create(web3.utils.fromAscii(ipfsHash)).send();
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const event = receipt.events.NewPost;
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postId = event.returnValues.postId;
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assert.equal(web3.utils.toAscii(event.returnValues.description), ipfsHash);
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```
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> This test demonstrates how to send a transaction to a contract. Since `create()` emits an event, we're able to access it in the transaction receipt, and we can use it to perform any assertion we need.
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### The post should have correct data
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```
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const post = await posts(postId).call();
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assert.equal(web3.utils.toAscii(post.description), ipfsHash);
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assert.equal(post.owner, accounts[0]);
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```
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> On this test, we read data from the chain, without generating a transaction. Notice we use `call()` instead of `send()` when invoking the `post()` function. A `call` will read the current state of our contract
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### We should't be able to vote twice for the same post
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```
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try {
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const receipt = await vote(postId, 1).send();
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assert.fail('should have reverted before');
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} catch (error){
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assert(error.message.search('revert') > -1, 'Revert should happen');
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}
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```
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> On this test we can see the pattern to evaluate a transaction that will revert. It involves using a try/catch block, and `assert.fail()` should be used to guarantee that it will fail the test if it reaches that line. Since `vote()` will revert, it throws an exception that we capture, and evaluate the error message to determine if the transaction reverted.
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### Running the tests
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To execute the tests and see their result, on a terminal session run:
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```
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embark test
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```
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### Results
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The results of your test unit should be similar to the following:
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```
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DReddit contract
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✓ should be able to create a post and receive it via contract event
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✓ should return 1 post
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✓ post should have correct data
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✓ should not be able to vote in an unexisting post report
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✓ should be able to vote in a post if account hasn't voted before
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✓ should be able to vote in a post
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✓ should't be able to vote twice
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7 passing (163ms)
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> All tests passed
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```
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