Testing blockchain technologies

Blockchain is the latest technology, attention to which has increased along with the popularity of cryptocurrencies. In this article, we will break down the basic concepts you need to know to understand blockchain: where it is used, its advantages and disadvantages, as well as how it is tested and what tools exist for it.

What is blockchain?

Blockchain (a chain of blocks) is a distributed database that stores an ordered chain of blocks that contain information and customer identification.

Blocks are organized in chronological order, connected to each other and protected by cryptographic methods.

General structure and organization of blocks

Each such block contains a hash code calculated from the previous block and a payload. The payload can include information about transactions, agreements, signed contracts, entering data about an individual, business entity, property, etc. into the register. In other words, almost any information can act as a payload. In fact, a blockchain is an ever-updating ledger of records. You can only add data to it, but you cannot delete or change those stored in previous blocks.

The technology is believed to have been invented by Satoshi Nakomoto, but it is not known for sure if a person with that name actually exists or if it is just a pseudonym of a group of people. First, blockchain technology was used in 2009 when creating the cryptocurrency «bitcoin» and gained wide popularity for the development of other cryptocurrencies, for example, ethereum (eth).

The positive qualities of the system contributed to its further penetration into the economy. This technology can be used to record and track any kind of information: from medical indicators to elections.

Blockchain is already used in:

• logistics (delivery system);
• health care;
• retail trade (to track the origin of products and goods);
• state bodies;
• oil industry;
• telecommunications and mass media;
• fight against piracy (for example, it is done by Microsoft).

The main principles of the technology are:

1. Decentralization – the process is not monitored by any organization or regulator, transactions are processed by a large number of special participants in the system – miners.
2. Distribution – information is not concentrated on servers in one place, but is located among a huge network of computers around the world.
3. Transparency – all network users have access to the history of transaction chains, everyone can check its authenticity.
4. Security – a high level of reliability is achieved due to advanced encryption methods.
5. Immutability – data in a blockchain network cannot be deleted or replaced, as it is verified by many network nodes.

All the principles listed above are the advantages of blockchain technology, but despite the fact that the technology has undeniable advantages, it also has its disadvantages.

1. Scalability. That is, as the number of participants increases, the system becomes increasingly difficult to process transactions. For example, Ethereum, the second largest cryptocurrency, faced this.
2. The so-called «51% attack». This means that if several network users who have large computing power agree, they can change the entries in a particular block. The cryptocurrency Bitcoin SV recently faced this. Hackers were able to gain control over the network and compromise more than 570,000 transactions.
3. For blockchains that are not used for cryptocurrencies – insufficient testing. Typically, cryptocurrencies have test networks where developers learn about network vulnerabilities. Businesses rarely check their blockchains in this way, so they are more prone to hacker attacks.

From the tester's point of view, the blockchain is primarily the functionality of the application. In 90% of cases, it is used as a type of payment system. The tests, accordingly, will be approximately the same as when testing payments:

• parameter validation;
• verification of the successful completion of the transaction;
• verification of additional conditions of requirements (for example, fulfillment of the terms of a smart contract).

What are the main characteristics of blockchain application testing?

First, creating an environment for testing. All operations carried out in the blockchain chain change the state of the network. Adding or changing records requires miners' resources, and accordingly requires a commission. Testing in the test network will help to avoid costs. Test networks use the same code as the main network, but you can get assets absolutely free using faucet resources. Faucet-resources provide a limited number of coins on the testnet for free for personal use.

Secondly, the irreversibility of operations. The absence of a central server means that 99% of errors, failures, substitutions, and any other illegal actions in the blockchain cannot be undone. If a transaction is added to the blockchain, it must be valid. 

This puts the maximum level of responsibility on the testing team. After all, the missed defect will almost always be critical.

Third, all transactions are paid. The tester checks how the addition and processing of transactions in the blockchain will take place. However, it should be remembered that all entries in the blockchain are paid and this imposes its own characteristics on the testing process. For example, when working with bitcoin, it should be taken into account that in addition to the amount of the transfer from above, a commission for the work of miners will be deducted.

The following types of testing will help ensure the high quality of products built on blockchain technology:

1. Functional Testing

• testing of smart contracts;
• transaction life cycle testing;
• testing communication between nodes and block synchronization;
• block finality testing.

      2. Non-Functional Testing

• performance testing: load, transaction delays, overall performance;
• security testing: impossibility of data theft, network penetration, system integrity;
• load testing: bandwidth of the system through which interaction with the blockchain takes place;
• resiliency testing: crash recovery, resilience.

There are special tools for testing blockchain technology. A list of the most popular of them will be given below.

Ganache (Testrpc)

It is a program that supports Ethereum and Corda technologies. Ganache can be used throughout the development cycle. It allows the creation of a private Ethereum blockchain to develop, deploy and test applications in a secure and deterministic environment and is used to test smart contracts during development.

Hyperledger Fabric testing tools: Operator і PTE  

Operator is capable of deploying custom Fabric networks on a local machine with Docker or Kubernetes. PTE (Performance Traffic Engine) is required to call and analyze the chaincode in the network created in Operator.

Exonum Testkit 

It is used to test the entire functionality of the blockchain program. It allows testing of APIs and transactions without a consensus algorithm and network connection.

Truffle

The most popular framework that allows you to write automated tests in both JavaScript and Solidity, supports automatic testing of contracts. Truffle is based on the Ethereum blockchain and is used to develop distributed applications.

BitcoinJ 

A Java-based library for working with Bitcoin-based applications.

BitcoinJ allows you to interact with the real BTC network and perform various testing activities.

Corda Testing Tools  

It is an open distributed blockchain platform. It has built-in testing tools: writing tests for contracts, integration tests, flow tests, load testing.

Ethereum Tester

It is an open source testing library. Ethereum Tester provides tools for testing Ethereum-based applications. It is easy to configure and control API support for different testing requirements. It is used to create blockchain-based applications.

Populus

A tool for testers who write Python tests. It is based on py.test and is easy to implement. This framework offers powerful utilities for testing contracts.

Manticore

It allows you to analyze smart contracts and automatically detects all possible vulnerabilities.

EmbarkJS

Similar to Truffle, but all tests are written in JavaScript. Focused on the development of decentralized applications (dApps) that work in different systems.

Finally, it is worth mentioning that the possibilities of blockchain are very large, although not all areas of application of the technology are covered today. Clearmatics predicts that blockchain testing, as a separate segment of QA, will be in high demand and a mandatory requirement for companies specializing in QA. On the horizon there are colossal volumes of testing and the need for experience in testing blockchain platforms. In any case, it should be remembered that a timely quality check of programs operating on the basis of blockchain will help to avoid data leakage and serious material losses.